How to use parent.Xrm.WebAPI in standalone web resources (not in CRM form)

Are you working with CRM on-premises and developing a standalone web resources without CRM form ? You can face with this trouble and this article is for you.

What is the issue?

Basically, we need to include a reference to ClientGlobalContext.js.aspx to HTML web resources but it does not make the Xrm object available. Therefore, scripts containing Xrm.* methods aren't supported in HTML web resources. And the scripts containing parent.Xrm.* will work if the HTML web resources is loaded in a form container. However, for other places, such as loading an HTML standalone web resources, parent.Xrm.* also won't work. If you try to use it on standalone web resources in on-premise environment version 9.1 (or 9.0), you will receive the error:

Root cause

After a lot of time to debug this error, I found it come from the Xrm.WebApi method. It is failing on a line where it attempts to take the entityname and resolve it to the setname (plural). It does this by comparing the value passed into the retrieveMultipleRecords method and comparing it to a global variable ENTITY_SET_NAMES.

This variable is unfortunately not present and parent.Xrm.WebApi throws an error.

Workaround

However, the standalone web resources is needed in some scenarios with specific business which we must accept the unsupported way to leverage the advantages of its and we could do a "magic" to use parent.Xrm.* into the standalone web resources.

Note: Please be aware that: This is the unsupported method.

First of all, we need to identify how many entities we work with parent.Xrm.WebApi in the web resource.

And those entities are not present in global variable ENTITY_SET_NAMES. So we create it.

In the window variable, we create an attribute ENTITY_SET_NAMES  is a JSON-parsable string which contains the logical name and set a name for each entity.

Finally, we need execute that function before any calls to parent.Xrm.WebApi methods appears to work.

Some final words

Now, your issue should be resolved. Hope that Microsoft will fix it soon and the article will become a good resource for you.

If you have any better solutions or any questions, feel free to comment below. Your opinions are appreciated.