[Bug] Cannot create N:N relations

[aabols]

Describe the bug

For an N:N relationship, the CLI allows to add the intersect table as a source. The generated service includes the usual methods. Attempting to create a new relation using the create() method fails. Reading with getAll() works.

Code Apps documentation doesn't mention any limitations or recommendations around N:N relationships (that I could find).

Steps to Reproduce

1. pac code add-data-source -a dataverse -t <intersect-table-logical-name>
2. Try to create a record using the generated service
3. See error

Expected behavior

New record created in intersect table.

Actual behavior

Request fails with error message.

Screenshots or Error Messages

{
    "code": "0x80040800",
    "message": "The 'Create' method does not support entities of type '<intersect-table-logical-name>'. MessageProcessorCache returned MessageProcessor.Empty. ",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionSourceKey": "Api/PrePipeline",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiStepKey": "00000000-0000-0000-0000-000000000000",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiDepthKey": "0",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiActivityIdKey": "f6d0c6ea-45b8-4a23-b60b-4d21ad628ce6",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiPluginSolutionNameKey": "System",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiStepSolutionNameKey": "System",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionCategory": "ClientError",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionMessageName": "SdkEntityDoesNotSupportMessage",
    "@Microsoft.PowerApps.CDS.ErrorDetails.ApiExceptionHttpStatusCode": "400",
    "@Microsoft.PowerApps.CDS.HelpLink": "http://go.microsoft.com/fwlink/?LinkID=398563&error=Microsoft.Crm.CrmException%3a80040800&client=platform",
    "@Microsoft.PowerApps.CDS.InnerError.Message": "The 'Create' method does not support entities of type '<intersect-table-logical-name>'. MessageProcessorCache returned MessageProcessor.Empty. "
}

Environment information

• pac v2.7.4+g06bb2eb

[eschavez]

Thanks for the report!

This is a Dataverse platform constraint: intersect tables for N:N relationships do not support the standard Create message, which is why you're seeing error 0x80040800 / SdkEntityDoesNotSupportMessage. Dataverse requires using the OData `` association endpoint instead of a direct POST to the entity set.

Workaround — until we add first-class N:N support in the generated service, you can call the association endpoint directly via fetch:

// Associate record1 (fromId) → record2 (toId) via the relationship
const dataverseUrl = "https://<your-env>.api.crm.dynamics.com";

await fetch(
  `/api/data/v9.2/<from-table>s()/<relationship-name>/`,
  {
    method: "POST",
    headers: { "Content-Type": "application/json", "OData-Version": "4.0" },
    body: JSON.stringify({
      "@odata.id": `/api/data/v9.2/<to-table>s()`
    })
  }
);

To disassociate, use a DELETE to:
/api/data/v9.2/<from-table>s()/<relationship-name>()/

We're logging this to our backlog to improve pac code add-data-source so it either detects N:N intersect tables and generates relationship-aware associate() / disassociate() methods, or surfaces a clear error at CLI time. We'll update this issue as we make progress.

[aabols]

Sounds good, thank you!

I wasn't sure if the "normal" Dataverse web API is fair game in code-apps, in terms of correctly inheriting the auth context, security roles etc., but I'm happy to hear that it is.

In the interim I have gone with "manual" intersect tables with two N:1 relationships 🙈

[aabols]

I have tried using the Dataverse web api from the code app, but the fetch() fails, because it "violates the document's Content Security Policy."

Am I missing something? Looks like the IFrame is preventing fetches to pass through. Am I supposed to use something from the SDK? I can't see any methods for invoking a "general" API endpoint.