How to enrich azure b2c token with custom claims using api connectors and asp net core web api

Question

I have a user flow B2C_1_singupsingin1 I added an api connector, embed it in this stream and the endpoint url for the API call. Used article: https://learn.microsoft.com/en-us/azure/active-directory-b2c/add-api-connector-token-enrichment?pivots=b2c-user-flow

It is clear from the article that the API connector materializes as an HTTP POST request, sending custom attributes.

My web api has an endpoint with the code:

[HttpPost("enrich")]
public IActionResult Enrich([FromBody] JsonElement body)
{
    var responseProperties = new Dictionary<string, object> //for example
    {
        { "version", "1.0.0" },
        { "action", "Continue" },
        { "postalCode", "12349" },
        { "userId", 123 } 
    };

    return new JsonResult(responseProperties) { StatusCode = 200 };
}

When I start a custom flow everything works, I get to that endpoint in api. But there is a problem JsonElement body does't contain custom attributes. Inside I see body.ValueKind = Undefined. Tell me what am I doing wrong?

Also, after all, I wanted to add a custom "userId" claim with some value from my database. So that it is contained in the token issued in the subsequent. Would the code above be correct for this?

Answer 1

Your code is fine. Just add "extension_" in front of postalCode and userId.

    [HttpPost("log")]
    public IActionResult Log([FromBody] JsonElement body)
    {

        var responseProperties = new Dictionary<string, object> 
        {
            { "version", "1.0.0" },
            { "action", "Continue" },
            { "extension_Role", "admin" },
        };

        return new JsonResult(responseProperties) { StatusCode = 200 };
    }

In my Azure AD B2C I have a custom attribute called "Role".

But in debug mode I saw that for all the custom attributes extension_ is set as prefix...

So by adding this to responseProperties it seems to be working.

Answer 2

I solved the problem a long time ago, but maybe my experience will help someone. First part of the question:

"The body of the JsonElement contains no custom attributes. Inside I see body.ValueKind = Undefined"

What was the problem. To support HTTP Patch requests, I added the NewtonsoftJson package and configuration to Startup:

services.AddControllers().AddNewtonsoftJson(x => 
{
   x.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
});

But I didn’t consider that AddNewtonsoftJson replaces the System.Text.Json-based input and output formatters used for formatting all JSON content. Because of this I was getting the above problem. Solution from Microsoft documentation

The solution to the second part of the question with a custom claims was provided by Steffen. You just need to add extension_ prefix to claim.