Batch Execute FetchXML using Web API

This is not usually the case but sometimes you may have a Fetch XML which is too large to be executed using a regular GET method and wish it had a post method. There is a way, by using Batch execution.

Things to note

Content-Type will be “multipart/mixed;boundary=mybatchname”

Data returned from the Web API cannot be directly parsed into JSON and needs some data-massaging.

Sample Code

var req = new XMLHttpRequest();
req.open("POST", Xrm.Page.context.getClientUrl() + "/api/data/v9.0/$batch", true);
req.setRequestHeader("OData-MaxVersion", "4.0");
req.setRequestHeader("OData-Version", "4.0");
req.setRequestHeader("Accept", "application/json");
req.setRequestHeader("Content-Type", "multipart/mixed;boundary=mybatch");
req.onreadystatechange = function() {
    if (this.readyState === 4) {
        req.onreadystatechange = null;
        if (this.status === 200) {
            var results = JSON.parse(this.response.substring(this.response.indexOf('{'),this.response.lastIndexOf('}')+1));
        } 
        else {
            Xrm.Utility.alertDialog(this.statusText);
        }
    }
};

var body = '--mybatch\n'
body += 'Content-Type: application/http\n'
body += 'Content-Transfer-Encoding: binary\n'
body += '\n'
body += 'GET ' + Xrm.Page.context.getClientUrl()+'/api/data/v9.0/accounts?fetchXml=<fetch count="10" ><entity name="account" ><attribute name="name" /></entity></fetch> HTTP/1.1\n'
body += 'Content-Type: application/json\n'
body += 'OData-Version: 4.0\n'
body += 'OData-MaxVersion: 4.0\n'
body += '\n'
body += '--mybatch--'

req.send(body);

• The POST URL is “$batch”
• Content-Type header contains the name of the batch
• Data returned from the Web API needs to be massaged to get the result
• Body of the request needs to be in certain format

Format of Request Body

--batchname
Content-Type: application/http
Content-Transfer-Encoding: binary

GET https://[CRM URL]/api/data/[CRM API Version]/[Entity's Plural Name]?fetchXml=[Fetch XML] HTTP/1.1
Content-Type: application/json
OData-Version: 4.0
OData-MaxVersion: 4.0

--batchname--

Formatting Response Data

Actual Response from Web API

--batchresponse_BatchGUID
Content-Type: application/http
Content-Transfer-Encoding: binary

HTTP/1.1 200 OK
Access-Control-Expose-Headers: Preference-Applied,OData-EntityId,Location,ETag,OData-Version,Content-Encoding,Transfer-Encoding,Content-Length,Retry-After
Content-Type: application/json; odata.metadata=minimal
OData-Version: 4.0

{"@odata.context":"https://[CRM URL]/api/data/v[CRM API Version]/$metadata#accounts(name,accountid)","@Microsoft.Dynamics.CRM.fetchxmlpagingcookie":"","value":[{"@odata.etag":"W/\"70232774\"","name":"XYZ1","accountid":"GUID1"},{"@odata.etag":"W/\"70348872\"","name":"XYZ2","accountid":"GUID2"}]}
--batchresponse_BatchGUID--

If you observe the actual data inside the batchresponse is between { and }. Hence we get the substring of the actual response using the code below.

var results = JSON.parse(this.response.substring(this.response.indexOf('{'),this.response.lastIndexOf('}')+1));

Hope this helps.