No route matches the supplied values

No route matches the supplied values

I spent about two hours figuring out why I was getting this error message for the Contacts API. I followed the Todo List example by the book so that if someone from the stream were confused, they would have something to fall back on. Unfortunately, it wasn’t totally by the book.

I have code in the API for saving the contact which looks like this:

public async Task<ActionResult<Contact>> SaveContact(Contact contact)
{
    HttpContext.VerifyUserHasAnyAcceptedScope(Domain.Permissions.Contacts.Save);
    var savedContact = await _contactManager.SaveContactAsync(contact);

    if (savedContact != null)
    {
        return CreatedAtAction(nameof(GetContactAsync),
            new {id = contact.ContactId},
            contact);
    }
    return Problem("Failed to insert the contact");
}

This code uses the CreatedAtAction to return the contact and the URL to view the contact details. However, this call kept returning an exception No route matches the supplied values. I made sure the method/action existed. Here it is!

[HttpGet("{id}")]
public async Task<Contact> GetContactAsync(int id)
{
    HttpContext.VerifyUserHasAnyAcceptedScope(Domain.Permissions.Contacts.View);
    return await _contactManager.GetContactAsync(id);
}

I double-checked all of the route settings. I double-checked the name of the ‘Get’ function, GetContactsAsync, and everything looked ok. I even tried to skip the nameof operator and just hard the GetContactsAsync, but I kept getting the exception No route matches the supplied values

I Googled and Binged for a while and did not come up with anything. Until I came to this StackOverflow question. The first answer was not the answer that solved my problem, but an answer below.

As the answer suggests, ASP.NET Routing has an issue with the method name ending in the word Async. As a result, it could not find my GetContactsAsync method.

So my options were to rename the method or not use the CreatedAtAction. I was not too fond of either option. The answer did suggest that I could use the ActionName attribute to inform the routing of what the actual name of the method is. I’ve updated the method as follows.

[HttpGet("{id}")]
[ActionName(nameof(GetContactAsync))]
public async Task<Contact> GetContactAsync(int id)
{
    HttpContext.VerifyUserHasAnyAcceptedScope(Domain.Permissions.Contacts.View);
    return await _contactManager.GetContactAsync(id);
}

So using the ActionName got me over the hurdle of ‘No route matches the supplied values.’ I hope this helps someone.