Attaching File from SharePoint Location in Email using Power Automate while working on D365 CRM

What is Issue?

When working on D365 CRM, Some processes needs to send notification as well as approval mails to particular users. In these emails some time users want the files to be attached which is uploaded for any particular record in CRM. Developer faces issue to get the file from SharePoint, because of very few columns available in SharePoint which is created by D365 CRM to SharePoint Integration. So the issues are like how to get the file from SharePoint and attach it email?

The Reason-

Using Workflow or custom plugin it will be much time consuming and also complex coding required with this approach. Developer can choose this approach for sending out simple notifications, emails. But when the requirements comes to file attachment from SharePoint or any other cloud location it will be difficult to handle with this approach. Also if the file is in SharePoint location which is configured using Document management in CRM, location will have limited set of columns, so it becomes difficult to query the SharePoint site using API also.

Solution-

For the first issue, which approach to choose in these scenarios-
Microsoft is already recommending users to use Power Automat instead of CRM Workflows. Power Automate is having multiple connectors and actions available which reduces the coding as well as time efforts. So we can choose Power Automate.

Now second Issue, How to get file from SharePoint location which is configured using Document Management in CRM?
As I already mentioned, Power Automate already having hundreds of connectors and actions, we can use the Get File Action in Power Automate. Now again you will be worried about how you can get particular file from this location as Tittle or any other field will not help here. So we can use FileLeafRef column filter for that.

Lets take scenario –

When user have opportunity where he uploads the template for Opportunity Activity logs in Document section. But before closing opportunity user needs the log template approved by his manager. Suppose there is flag when user submits the approval request.

  1. Trigger action for my Power Automate flow will be “Microsoft Dataverse when a row is added, modified or deleted where I will set row filter as AwaitngApprovalflag eq 1
  2. Now we need to initialize the Array which will work as byte array to store the file retrieved from the SharePoint.
  3. Add new SharePoint action “Get File(Properties Only)” and set SharePoint details with Filter Query – FileLeafRef eq “filename.xlsx” (this will be my log file template name)

4. Now add the SharePoint action “Get File Content” and set site address as SharePoint site, File Identifier as identifier from last action i.e. “Get File (Properties Only)”. This will automatically add Apply to Each loop.
5. Append the Array variable with File Content and file name from the above action “Get File Content”.
Example-
{
“FileName”:”fileName.xlsx”,
“ContentByte”:FileContent
}

7. Add action “Send Email With Option” and set participant and email body, and other details. In attachment section set the Array Variable which we initialized and configured with file content.

8. Add condition action and check the response from the manager in Email like he clicked on Approve or Reject button in email. and based on condition perform the next actions on your D365 CRM Record.

9. The Complete Flow looks like-

Hope this will help…
Enjoy Ms CRM!!!

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Batch operation ($batch) using OData API Dynamics 365

What is Issue?

There are OData API provided by Microsoft to perform operations on D365 Tables like Create, update, delete and retrieve. These operations can be perform individually by building the OData API using some tools or with your knowledge. But some time there are the cases where you need to call the bulk create, bulk update, bulk delete or some bulk create and bulk update/delete simultaneously. If there are more than one records, you need to hit OData API one by one multiple times which takes cost in terms of time and performance of the application which is calling OData API. Is there a way to combine these all requests in one call and execute?

The Reason-

There is way to perform the CRUD operations on D365 Tables using OData, but everyone aware of the single operations. Microsoft provides the way to perform Batch operation on Tables using OData API. Lets see in solution for this.

Solution-

Microsoft D365 provides the OData for batch operation to perform using “$batch” like-

https://your_org.crm8.dynamics.com/api/data/v8.2/$batch

You need to include the all other CRUD (POST, PATCH, DELETE, GET) OData APIs in the body for the above request URL.

This request works like all other OData APIs using OAuth2.0 authentication with proper headers added.

Lets take .Net application where I need to perform the Create, update and some delete operation in one call.

You have to prepare your request as below-

Preparing the Batch Call-

#region prepare Batch Call
        private string BatchQueryCall(string crmRestQuery, string batchName, string requestBody)
        {
            string funResponse = null;
            try
            {
                HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, crmRestQuery);
                //add header parameters
                request.Headers.Add("Authorization", "Bearer " + oauthToken);
                request.Headers.Add("Accept", "application/json");
                request.Content = new StringContent(requestBody);
                request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/mixed;boundary=" + batchName);

                HttpResponseMessage response = httpClient.SendAsync(request).Result;
                string responseString = response.Content.ReadAsStringAsync().Result;

                if (response.IsSuccessStatusCode)
                {
                    funResponse = responseString;
                }
                else
                    funResponse = responseString;

            }
            catch (Exception ex)
            {
                funResponse = ex.Message;
            }
            return funResponse;
        }
        #endregion

Preparing to Call Batch Operation-

Suppose I have to create one record, update one record and delete 2 records in same call.
Below code helps you to understand preparing the Batch call-

  #region bulk Operations
        public string BulkOperationsAPI(string entityname)
        {
            #region Local Variable
            string crmRestQuery = apiUrl + "$batch";
            string batchName = "batch_bt123";
            string changeSetVar = "changeset_ch123";
            int coRelId = 1;
            string changeSet1 = null;
            string requestBody = "--" + batchName + Environment.NewLine
                             + "Content-Type:multipart/mixed;boundary=" + changeSetVar + Environment.NewLine + Environment.NewLine + Environment.NewLine;
            #endregion

            #region Create
                //Creating one record
                CreateUpdateOpportunity entity = new CreateUpdateOpportunity();

                entity.transactioncurrencyid_odata_bind = "/transactioncurrencies(c63ba581-6bc6-e811-a96f-000d3af04fb0)";
                entity.estimatedvalue = 1000;
                entity.estimatedclosedate = "2021-01-01";
                entity.name = "Generated From C# Code";
                entity.parentaccountid_odata_bind = "/accounts(3b3b7c71-61d2-ea11-a813-000d3af0205e)";

                changeSet1 = PrepareReuqestBody("POST", changeSetVar, coRelId++, entityname, null, entity);

                if (!string.IsNullOrEmpty(changeSet1))
                    requestBody += changeSet1 + Environment.NewLine;
            
            #endregion

            #region Update
                //updating One record
                CreateUpdateOpportunity entity1 = new CreateUpdateOpportunity();

                entity1.transactioncurrencyid_odata_bind = "/transactioncurrencies(c63ba581-6bc6-e811-a96f-000d3af04fb0)";
                entity1.estimatedvalue = 1000;
                entity1.estimatedclosedate = "2021-01-01";
                entity1.name = "Generated From CSharp Code";
                entity1.parentaccountid_odata_bind = "/accounts(3b3b7c71-61d2-ea11-a813-000d3af0205e)";

                changeSet1 = PrepareReuqestBody("PATCH", changeSetVar, coRelId++, entityname, "20e6bb72-2861-eb11-a812-0022486e93ce", entity1);

                if (!string.IsNullOrEmpty(changeSet1))
                    requestBody += changeSet1 + Environment.NewLine;
            #endregion

            #region Delete
            //delete 1st record  
            changeSet1 = PrepareReuqestBody("DELETE", changeSetVar, coRelId++, entityname, "29e6bb72-2861-eb11-a812-0022486e93ce", null);
                if (!string.IsNullOrEmpty(changeSet1))
                    requestBody += changeSet1 + Environment.NewLine;

            //delete 2nd record
            changeSet1 = PrepareReuqestBody("DELETE", changeSetVar, coRelId++, entityname, "27e6bb72-2861-eb11-a812-0022486e93ce", null);
            if (!string.IsNullOrEmpty(changeSet1))
                requestBody += changeSet1 + Environment.NewLine;
            #endregion


            requestBody += "--" + changeSetVar + "--" + Environment.NewLine;
            requestBody += "--" + batchName + "--";
            
            //format the body URLs
            requestBody = requestBody.Replace("\\/", "/");  

            //call the batch Operations
            return BatchQueryCall(crmRestQuery, batchName, requestBody);
        }
        #endregion

Preparing the body content of Batch call-

In above code there is call made to the function PrepareRequestBody-
This function will prepare the body content of Batch call.

        #region Prepare Request Body
        private string PrepareReuqestBody(string method, string changeset, int contentId, string entityName, string recordid, object entity)
        {

            string x = null;
            switch (method.ToUpper())
            {
                case "PATCH":
                    using (MemoryStream streamOpportunitySerialize = new MemoryStream())
                    {
                        DataContractJsonSerializer ser = new DataContractJsonSerializer(entity.GetType());
                        ser.WriteObject(streamOpportunitySerialize, entity);
                        streamOpportunitySerialize.Position = 0;
                        StreamReader srOpportunity = new StreamReader(streamOpportunitySerialize);
                        string objectJSON = srOpportunity.ReadToEnd();
                        objectJSON = objectJSON.Replace("_odata_bind", "@odata.bind");

                        x = "--" + changeset + Environment.NewLine
                            + "Content-Type: application/http" + Environment.NewLine
                            + "Content-Transfer-Encoding: binary" + Environment.NewLine
                            + "Content-ID: " + contentId + Environment.NewLine + Environment.NewLine
                            + "PATCH " + apiUrl + entityName + "(" + recordid + ") HTTP/1.1" + Environment.NewLine
                            + "Content-Type: application/json;type=entry" + Environment.NewLine
                            + "Accept:application/json" + Environment.NewLine + Environment.NewLine
                            + objectJSON + Environment.NewLine + Environment.NewLine;
                    }
                    break;
                case "POST":
                    using (MemoryStream streamOpportunitySerialize = new MemoryStream())
                    {
                        DataContractJsonSerializer ser = new DataContractJsonSerializer(entity.GetType());
                        ser.WriteObject(streamOpportunitySerialize, entity);
                        streamOpportunitySerialize.Position = 0;
                        StreamReader srOpportunity = new StreamReader(streamOpportunitySerialize);
                        string objectJSON = srOpportunity.ReadToEnd();
                        objectJSON = objectJSON.Replace("_odata_bind", "@odata.bind");

                        x = "--" + changeset + Environment.NewLine
                            + "Content-Type: application/http" + Environment.NewLine
                            + "Content-Transfer-Encoding: binary" + Environment.NewLine
                            + "Content-ID: " + contentId + Environment.NewLine + Environment.NewLine
                            + "POST " + apiUrl + entityName + " HTTP/1.1" + Environment.NewLine
                            + "Content-Type: application/json;type=entry" + Environment.NewLine
                            + "Accept:application/json" + Environment.NewLine + Environment.NewLine
                            + objectJSON + Environment.NewLine + Environment.NewLine;
                    }

                    break;
                case "DELETE":
                    x = "--" + changeset + Environment.NewLine
                    + "Content-Type: application/http" + Environment.NewLine
                    + "Content-Transfer-Encoding: binary" + Environment.NewLine
                    + "Content-ID: " + contentId + Environment.NewLine + Environment.NewLine
                    + "DELETE " + apiUrl + entityName + "(" + recordid + ") HTTP/1.1" + Environment.NewLine
                    + "Accept:application/json" + Environment.NewLine + Environment.NewLine;
                    break;
            }

            return x;
        }
        #endregion

Request Body content will look like-

--batch_bt123
Content-Type:multipart/mixed;boundary=changeset_ch123


--changeset_ch123
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 1

POST https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities HTTP/1.1
Content-Type: application/json;type=entry
Accept:application/json

{"estimatedclosedate":"2021-01-01","estimatedvalue":1000,"name":"Generated From C# Code","parentaccountid@odata.bind":"/accounts(3b3b7c71-61d2-ea11-a813-000d3af0205e)","transactioncurrencyid@odata.bind":"/transactioncurrencies(c63ba581-6bc6-e811-a96f-000d3af04fb0)"}


--changeset_ch123
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 2

PATCH https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities(d659b4d6-0f5b-eb11-a812-6045bd727e64) HTTP/1.1
Content-Type: application/json;type=entry
Accept:application/json

{"estimatedclosedate":"2021-01-01","estimatedvalue":1000,"name":"Generated From CSharp Code","parentaccountid@odata.bind":"/accounts(3b3b7c71-61d2-ea11-a813-000d3af0205e)","transactioncurrencyid@odata.bind":"/transactioncurrencies(c63ba581-6bc6-e811-a96f-000d3af04fb0)"}


--changeset_ch123
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 3

DELETE https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities(46c9eab1-5ac2-4673-a55a-51cb886db902) HTTP/1.1
Accept:application/json


--changeset_ch123
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 4

DELETE https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities(d659b4d6-0f5b-eb11-a812-6045bd727e64) HTTP/1.1
Accept:application/json


--changeset_ch123--
--batch_bt123--

Response recieved will be like-

  --batchresponse_319a4c10-b7fe-4bf0-b4a6-da016d1c0319
Content-Type: multipart/mixed; boundary=changesetresponse_ee30dcdb-1094-4c24-8170-262eae9336a4

--changesetresponse_ee30dcdb-1094-4c24-8170-262eae9336a4
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 1

HTTP/1.1 204 No Content
OData-Version: 4.0
Location: https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities(3d4916b4-3861-eb11-a812-0022486e93ce)
OData-EntityId: https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities(3d4916b4-3861-eb11-a812-0022486e93ce)


--changesetresponse_ee30dcdb-1094-4c24-8170-262eae9336a4
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 2

HTTP/1.1 204 No Content
OData-Version: 4.0
Location: https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities(d659b4d6-0f5b-eb11-a812-6045bd727e64)
OData-EntityId: https://your_org.crm8.dynamics.com/api/data/v8.2/opportunities(d659b4d6-0f5b-eb11-a812-6045bd727e64)


--changesetresponse_ee30dcdb-1094-4c24-8170-262eae9336a4
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 3

HTTP/1.1 204 No Content
OData-Version: 4.0


--changesetresponse_ee30dcdb-1094-4c24-8170-262eae9336a4
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 4

HTTP/1.1 204 No Content
OData-Version: 4.0


--changesetresponse_ee30dcdb-1094-4c24-8170-262eae9336a4--
--batchresponse_319a4c10-b7fe-4bf0-b4a6-da016d1c0319--

For Token Generation you can refer the code in my last blog – https://mscrm16tech.com/2021/01/21/crud-operations-on-dynamics-365-crm-tables-with-odata-api/

Hope this will help…
Enjoy Ms CRM!!!

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CRUD Operations on Dynamics 365 CRM Tables with ODATA API

What is Issue?

Performing CRUD operation on Dynamics 365 CRM using API (Rest/ODATA) from other applications.

The Reason-

While performing integration of other application with CRM, creating custom Web API and webservice is having much efforts in terms of time and development. Microsoft already made developers job easy by providing the ODATA API available for their products. How to consume that API in other applications.

Solution-

While performing integration of other application with CRM, rather than creating the custom API or webservice, we can utilize ODATA APIs that can be consumed with the OAuth 2.0 authentication.

Lets take .net application which is consuming ODATA API.

Some time we don’t want to include any third party dll due to some environmental restrictions. so the sample code added below is using only system libraries.

(In case of Json serialization, you can utilize Newtonsoft.Json to avoid the classes to be written manually)

Create records using ODATA API-

#region Create API Call
        /// <summary>
        /// Create the entity Record using API Call
        /// </summary>
        /// <param name="entityname">entity Name</param>
        /// <param name="entity">entity Object with parameter values</param>
        /// <returns></returns>
        public string CreateAPI(string entityname, object entity)
        {
            string funResponse = null;
            string query = entityname;
            string crmRestQuery = apiUrl + query;

            try
            {
                using (MemoryStream streamOpportunitySerialize = new MemoryStream())
                {
                    DataContractJsonSerializer ser = new DataContractJsonSerializer(entity.GetType());
                    ser.WriteObject(streamOpportunitySerialize, entity);
                    streamOpportunitySerialize.Position = 0;
                    StreamReader srOpportunity = new StreamReader(streamOpportunitySerialize);
                    string objectJSON = srOpportunity.ReadToEnd();
                    objectJSON = objectJSON.Replace("_odata_bind", "@odata.bind");

                    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, crmRestQuery);
                    //add header parameters
                    request.Headers.Add("Authorization", "Bearer " + oauthToken);
                    request.Content = new StringContent(objectJSON);
                    request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json; charset=utf-8");

                    HttpResponseMessage response = httpClient.SendAsync(request).Result;
                    string responseString = response.Content.ReadAsStringAsync().Result;

                    if (response.IsSuccessStatusCode)
                    {
                        string _recordUrl = response.Headers.GetValues("OData-EntityId").FirstOrDefault();
                        string[] splitRetrievedData = _recordUrl.Split('[', '(', ')', ']');
                        funResponse = splitRetrievedData[1];
                    }
                    else
                        funResponse = responseString;

                }
            }
            catch (Exception ex)
            {
                funResponse = ex.Message;
            }
            return funResponse;
        }
        #endregion

Update records using ODATA API-

  #region Update API Call
        /// <summary>
        /// Update the entity record using API Call
        /// </summary>
        /// <param name="entityname">entity name</param>
        /// <param name="entityid">entity id</param>
        /// <param name="entity">entity Object with parameter values</param>
        /// <returns></returns>
        public string UpdateAPI(string entityname, string entityid, object entity)
        {
            string funResponse = null;
            string query = entityname + "(" + entityid + ")";
            string crmRestQuery = apiUrl + query;
            try
            {
                using (MemoryStream streamOpportunitySerialize = new MemoryStream())
                {

                    DataContractJsonSerializer ser = new DataContractJsonSerializer(entity.GetType());
                    ser.WriteObject(streamOpportunitySerialize, entity);
                    streamOpportunitySerialize.Position = 0;
                    StreamReader srOpportunity = new StreamReader(streamOpportunitySerialize);
                    string objectJSON = srOpportunity.ReadToEnd();
                    objectJSON = objectJSON.Replace("_odata_bind", "@odata.bind");

                    HttpMethod method = new HttpMethod("PATCH");
                    HttpRequestMessage request = new HttpRequestMessage(method, crmRestQuery);
                    //add header parameters
                    request.Headers.Add("Authorization", "Bearer " + oauthToken);
                    request.Headers.Add("If-Match", "*");      //preventing creation of new record if no record found with ID
                    request.Content = new StringContent(objectJSON);
                    request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json; charset=utf-8");

                    HttpResponseMessage response = httpClient.SendAsync(request).Result;
                    string responseString = response.Content.ReadAsStringAsync().Result;
                    if (response.IsSuccessStatusCode)
                    {
                        funResponse = "Sucessfully Updated Record!!";
                    }
                    else
                        funResponse = responseString;
                }
            }
            catch (Exception ex)
            {
                funResponse = ex.Message;
            }
            return funResponse;
        }
        #endregion

Delete records using ODATA API-

#region Delete API Call
        /// <summary>
        /// Delete the entity Record using API Call
        /// </summary>
        /// <param name="entityname">entity Name</param>
        /// <param name="entityid">Entity id</param>
        /// <returns></returns>
        public string DeleteAPI(string entityname, string entityid)
        {
            string funResponse = null;
            string query = entityname + "(" + entityid + ")";
            string crmRestQuery = apiUrl + query;

            try
            {
                HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Delete, crmRestQuery);
                //add header parameters
                request.Headers.Add("Authorization", "Bearer " + oauthToken);
                request.Headers.Add("Accept", "application/json; charset=utf-8");

                HttpResponseMessage response = httpClient.SendAsync(request).Result;
                string responseString = response.Content.ReadAsStringAsync().Result;
                if (response.IsSuccessStatusCode)
                    funResponse = "Deleted!!!";
                else
                    funResponse = responseString;
            }
            catch (Exception ex)
            {
                funResponse = ex.Message;
            }
            return funResponse;
        }
        #endregion

Retrieve Single record using ODATA API-

 /// <summary>
        /// Retrieve single using API Call
        /// </summary>
        /// <param name="entityPluralName">entity Name</param>
        /// <param name="entityId">entity id</param>
        /// <param name="entityObject">blank entity object</param>
        /// <param name="selectColumns">select columns to retrieve in API Call</param>
        /// <returns>Object of entity</returns>
        public object RetrieveSingle(string entityPluralName,string entityId,object entityObject, string selectColumns=null)
        {
            string query = "("+entityId+")";
            if (selectColumns != null) {
                query += "?$select=" + selectColumns;
            }
            string crmRestQuery = apiUrl + entityPluralName + query;
            try
            {
                    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, crmRestQuery);
                    //add header parameters
                    request.Headers.Add("Prefer", "odata.include-annotations=\"*\"");//for formatted values
                    request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/XML"));
                    request.Headers.Add("Authorization", "Bearer " + oauthToken);

                    //send request
                    HttpResponseMessage response = httpClient.SendAsync(request).Result;
                    string responseString = response.Content.ReadAsStringAsync().Result;
                    responseString = FormatResponse(responseString);

                    using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(responseString)))
                    {
                        // Deserialization from JSON  
                        DataContractJsonSerializer deserializer = new DataContractJsonSerializer(entityObject.GetType());
                    entityObject = (object)deserializer.ReadObject(ms);
                    }
                    
            }
            catch (Exception ex){ throw ex; }
            return entityObject;
        }

Retrieve Multiple records using ODATA API-

  /// <summary>
        /// Retrieve multiple using Fetch XML in API Call
        /// </summary>
        /// <param name="entityPluralName">entity name</param>
        /// <param name="fetchXML">fetchXML string</param>
        /// <returns>List of retrieved Objects</returns>
        public List<RetrieveOpportunity> RetrieveMultiple(string entityPluralName, string fetchXML)
        {
            fetchXML = fetchXML.Replace("<fetch", "<fetch {0} ");
            int page = 1;
            var cookie = string.Format("page='{0}'", page);
            string xml = string.Format(fetchXML, cookie);
            string crmRestQuery = apiUrl + entityPluralName + "?fetchXml=" + xml;
            List<RetrieveOpportunity> lstOpties = new List<RetrieveOpportunity>();
            bool isDone = false;
            try
            {
                while (isDone == false)
                {
                    isDone = true;
                    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, crmRestQuery);
                    //add header parameters
                    request.Headers.Add("Prefer", "odata.include-annotations=\"*\"");//for formatted values
                    request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/XML"));
                    request.Headers.Add("Authorization", "Bearer " + oauthToken);

                    //send request
                    HttpResponseMessage response = httpClient.SendAsync(request).Result;
                    string responseString = response.Content.ReadAsStringAsync().Result;
                    responseString = FormatResponse(responseString);

                    using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(responseString)))
                    {
                        // Deserialization from JSON  
                        DataContractJsonSerializer deserializer = new DataContractJsonSerializer(typeof(APIResult));
                        APIResult apiResult = (APIResult)deserializer.ReadObject(ms);

                        if (!string.IsNullOrEmpty(apiResult.Microsoft_Dynamics_CRM_fetchxmlpagingcookie))
                        {
                            isDone = false;
                            page++;

                            //retrieve pagingCookie value
                            string xmlVal = WebUtility.UrlDecode((WebUtility.UrlDecode((string)apiResult.Microsoft_Dynamics_CRM_fetchxmlpagingcookie)));
                            int Start = xmlVal.IndexOf("pagingcookie=\"", 0) + "pagingcookie=\"".Length;
                            int End = xmlVal.IndexOf("\" istracking=\"False\"", Start);

                            //proccess the pagingCookie value to support in API URL
                            string strVal = xmlVal.Substring(Start, End - Start).Replace("<", "%26lt;").Replace(">", "%26gt;").Replace("\"", "%26quot;").Replace("'", "%26apos;").Replace("&", "%26amp;");
                            cookie = string.Format("page='{0}' paging-cookie='{1}'", page, strVal);

                            //modify the query for next page with paging cookie
                            xml = string.Format(fetchXML, cookie);
                            crmRestQuery = apiUrl + entityPluralName +"?fetchXml=" + xml;

                        }
                        if (!string.IsNullOrEmpty(apiResult.odata_nextLink))
                        {
                            isDone = false;
                            crmRestQuery = apiResult.odata_nextLink;
                        }

                        if (lstOpties == null || lstOpties.Count == 0)
                        {
                            lstOpties = apiResult.value;
                        }
                        else
                        {
                            lstOpties.AddRange(apiResult.value);
                        }
                    }
                }
            }
            catch (Exception ex) {
                throw ex;
            }
            return lstOpties;
        }

        public List<RetrieveOpportunity> RetrieveMultiple(string entityPluralName, string selectColumns,string filterConditions=null, string orderby=null,bool returnCount=false)
        {
           string query= "?$select=" + selectColumns;
            if (filterConditions != null) {
                query += "&$filter=" + filterConditions;
            }
            if (orderby != null) {
                query += "&$orderby=" + orderby;
            }
            if (returnCount == true) {
                query += "&$count=true";
            }

            string crmRestQuery = apiUrl + entityPluralName +  query;
            List<RetrieveOpportunity> lstOpties = new List<RetrieveOpportunity>();
            bool isDone = false;
            try
            {
                while (isDone == false)
                {
                    isDone = true;
                    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, crmRestQuery);
                    //add header parameters
                    request.Headers.Add("Prefer", "odata.include-annotations=\"*\"");//for formatted values
                    request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/XML"));
                    request.Headers.Add("Authorization", "Bearer " + oauthToken);

                    //send request
                    HttpResponseMessage response = httpClient.SendAsync(request).Result;
                    string responseString = response.Content.ReadAsStringAsync().Result;
                    responseString = FormatResponse(responseString);

                    using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(responseString)))
                    {
                        // Deserialization from JSON  
                        DataContractJsonSerializer deserializer = new DataContractJsonSerializer(typeof(APIResult));
                        APIResult apiResult = (APIResult)deserializer.ReadObject(ms);
                        
                        if (!string.IsNullOrEmpty(apiResult.odata_nextLink))
                        {
                            isDone = false;
                            crmRestQuery = apiResult.odata_nextLink;
                        }

                        if (lstOpties == null || lstOpties.Count == 0)
                        {
                            lstOpties = apiResult.value;
                        }
                        else
                        {
                            lstOpties.AddRange(apiResult.value);
                        }

                    }
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return lstOpties;
        }

Some common Methods in above Code –

  #region Local variables
        /// <summary>
        /// Local Variables
        /// </summary>
        private string clientID, secretKey, resource, oauthToken, apiUrl, tokenURL;
        private HttpClient httpClient;

        /// <summary>
        /// Constructor to initialize the variables
        /// </summary>
        public Operations()
        {
            apiUrl = "https://mscrm16tech.crm8.dynamics.com/api/data/v8.2/";
            clientID = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
            secretKey = "asdasdxzxczdsdaasda";
            resource = "https://mscrm16tech.crm8.dynamics.com";
            tokenURL = "https://login.microsoftonline.com:443/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/oauth2/token/";
        }
        #endregion 
 #region Generate Bearer Token
        /// <summary>
        /// Function to generate Bearer token OAuth2.0 using client id and secret
        /// </summary>
        /// <returns>access token</returns>
        public string GetBearerToken()
        {
            oauthToken = null;
            HttpClientHandler clientHandler = new HttpClientHandler();
            clientHandler.Proxy = WebRequest.GetSystemWebProxy();
            clientHandler.Proxy.Credentials = CredentialCache.DefaultCredentials; // or new NetworkCredential("username","password","DOMAIN");
            clientHandler.UseProxy = true;
            httpClient = new HttpClient(clientHandler);
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
            HttpContent requestContent = new FormUrlEncodedContent(new Dictionary<string, string>
            {
                {"grant_type","client_credentials"},
                {"client_id",clientID},
                {"client_secret",secretKey},
                {"resource",resource}
            }
            );
            HttpResponseMessage response = httpClient.PostAsync(tokenURL, requestContent).Result;
            String responseString = response.Content.ReadAsStringAsync().Result;
            using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(responseString)))
            {
                // Deserialization from JSON  
                DataContractJsonSerializer deserializer = new DataContractJsonSerializer(typeof(BearerToken));
                BearerToken token = (BearerToken)deserializer.ReadObject(ms);
                oauthToken = token.access_token;
            }

            return oauthToken;
        }
        #endregion
#region Common Methods
       public string FormatResponse(string responseString) {
            responseString = responseString.Replace("@odata.etag", "odata_etag");
            responseString = responseString.Replace("@OData.Community.Display.V1.FormattedValue", "_OData_Community_Display_V1_FormattedValue");
            responseString = responseString.Replace("@Microsoft.Dynamics.CRM.associatednavigationproperty", "_Microsoft_Dynamics_CRM_associatednavigationproperty");
            responseString = responseString.Replace("@Microsoft.Dynamics.CRM.lookuplogicalname", "_Microsoft_Dynamics_CRM_lookuplogicalname");
            responseString = responseString.Replace("@Microsoft.Dynamics.CRM.lookuplogicalname", "_Microsoft_Dynamics_CRM_lookuplogicalname");
            responseString = responseString.Replace("@odata.context", "odata_context");
            responseString = responseString.Replace("@Microsoft.Dynamics.CRM.totalrecordcount", "Microsoft_Dynamics_CRM_totalrecordcount");
            responseString = responseString.Replace("@Microsoft.Dynamics.CRM.totalrecordcountlimitexceeded", "Microsoft_Dynamics_CRM_totalrecordcountlimitexceeded");
            responseString = responseString.Replace("@Microsoft.Dynamics.CRM.fetchxmlpagingcookie", "Microsoft_Dynamics_CRM_fetchxmlpagingcookie");
            responseString = responseString.Replace("@Microsoft.Dynamics.CRM.morerecords", "Microsoft_Dynamics_CRM_morerecords");
            responseString = responseString.Replace("@odata.nextLink", "odata_nextLink");
            return responseString;
        }
        #endregion

Sample Class for Json Serialization in API Calls-

This class is not needed in you are using Newtonsoft.Json library.

using System.Collections.Generic;
using System.Runtime.Serialization;

namespace ODATA_API
{
    [DataContract]
    public class BearerToken
    {
        [DataMember]
        public string token_type;
        [DataMember]
        public string expires_in;
        [DataMember]
        public string ext_expires_in;
        [DataMember]
        public string expires_on;
        [DataMember]
        public string not_before;
        [DataMember]
        public string resource;
        [DataMember]
        public string access_token;
    }

    [DataContract]
    public class CreateUpdateOpportunity {
        [DataMember]
        public string name;
        [DataMember]
        public string estimatedclosedate;
        [DataMember]
        public string parentaccountid_odata_bind;
        [DataMember]
        public decimal estimatedvalue;
        [DataMember]
        public string transactioncurrencyid_odata_bind;
    }
    [DataContract]
    public class RetrieveOpportunity
    {
        [DataMember]
        public string _odata_context;
        [DataMember]
        public string _odata_etag;
        [DataMember]
        public string estimatedclosedate_OData_Community_Display_V1_FormattedValue;
        [DataMember]
        public string estimatedclosedate;
        [DataMember]
        public string estimatedvalue_OData_Community_Display_V1_FormattedValue;
        [DataMember]
        public string estimatedvalue;
        [DataMember]
        public string estimatedvalue_base_OData_Community_Display_V1_FormattedValue;
        [DataMember]
        public string estimatedvalue_base;
        [DataMember]
        public string name;
        [DataMember]
        public string _parentaccountid_value_OData_Community_Display_V1_FormattedValue;
        [DataMember]
        public string _parentaccountid_value;
        [DataMember]
        public string opportunityid;
        [DataMember]
        public string _transactioncurrencyid_value_OData_Community_Display_V1_FormattedValue;
        [DataMember]
        public string _transactioncurrencyid_value;
    }

    [DataContract]
    public class APIResult
    {
        [DataMember]
        public string odata_context;
        [DataMember]
        public int Microsoft_Dynamics_CRM_totalrecordcount;
        [DataMember]
        public bool Microsoft_Dynamics_CRM_totalrecordcountlimitexceeded;
        [DataMember]
        public string Microsoft_Dynamics_CRM_fetchxmlpagingcookie;
        [DataMember]
        public bool Microsoft_Dynamics_CRM_morerecords;
        [DataMember]
        public string odata_nextLink;
        [DataMember]
        public List<RetrieveOpportunity> value;
    }

}

Calling the Above methods Sample-

static void Main(string[] args)
        {
            Operations ops = new Operations();
            Console.WriteLine("Started!!");
            Console.WriteLine(ops.GetBearerToken());
            
            CreateUpdateOpportunity entity = new CreateUpdateOpportunity();

            entity.transactioncurrencyid_odata_bind = "/transactioncurrencies(c63ba581-6bc6-e811-a96f-000d3af04fb0)";
            entity.estimatedvalue = 1000;
            entity.estimatedclosedate = "2021-01-01";
            entity.name = "Generated From C# Code";
            entity.parentaccountid_odata_bind = "/accounts(3b3b7c71-61d2-ea11-a813-000d3af0205e)";
            //create record
            string recordGuid = ops.CreateAPI("opportunities", entity);
            Console.WriteLine(recordGuid);
           
            //update record
            entity.name = "Generated From CSharp Code";
            Console.WriteLine(ops.UpdateAPI("opportunities", recordGuid, entity));

            //retrieve record
            RetrieveOpportunity retrieveOpportunity = new RetrieveOpportunity();
            retrieveOpportunity =(RetrieveOpportunity)ops.RetrieveSingle("opportunities", recordGuid,retrieveOpportunity);
            Console.WriteLine(retrieveOpportunity.name);

            //delete Record
            Console.WriteLine(ops.DeleteAPI("opportunities", recordGuid));


            Console.Read();
        }

Hope this will help…
Enjoy Ms CRM!!!

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