Setting null for single-valued navigation property using Xrm.WebApi

Question

We are in the process of remediation, re-engineering old JS web resources for latest D365 v9 sdk changes w.r.t Client scripting API improvements & deprecation.

W

Answer 1

Great news! You can set lookup field to null in PATCH request by adding this header to your request.

autodisassociate: true

And then you can use something like this to alter your lookup field in any way:

SetLookupField(requestBody, "systemusers", "msdfm_MyUser", null)
// Or
SetLookupField(requestBody, "systemusers", "msdfm_MyUser", "f5b0b514-aea8-ea11-a812-000d3a569fe1")

// ...

private static void SetLookupField(JObject requestBody, string typePlural, string name, string value)
{
    if (!string.IsNullOrEmpty(value))
    {
        requestBody.Add($"{name}@odata.bind", $"/{typePlural}({value})");
    }
    else
    {
        requestBody.Add($"_{name.ToLower()}_value", null);
    }
}

OP uses XMLHttpRequest anyway, so I thought, a way to do this using PATCH will be relevant here.