Bind WebAPI properties without action parameter

Question

A lot of our Web API action patterns have the following pattern:

public IHttpActionResult GetDetails(Guid customerGuid)
{
    Customer customer = customerRetriever.FromGuid(customerGuid);

    if (customer == null)
        return NotFound();

    // Do Stuff....
}

I want to move all the customer lookup boiler plate out of the action method. I created an action filter attribute to do this, by looking at the value of the action argument and setting a request property:

KeyValuePair<String, Object> argument = actionContext.ActionArguments.Single(kvp => kvp.Key.Equals(ParameterName));
Guid customerGuid = (Guid)argument.Value;
// Do customer lookup, return 404 if needed
// Add customer to request properties

This works, but i still need to include the now redundant Guid in my action signature. If i remove this, my approach for finding the Guid value fails. Is there a way to bind a value from the URI, without having that value as an action parameter?

is the customer id the id if the user making the call? or is the user making a call to view a particular customer? If the former then that is what authentication and authorization action filters are for. — Nkosi
– Nkosi, Commented Mar 29, 2017 at 23:29

Jignesh Variya · Accepted Answer · 2017-03-30 09:53:09Z

0

You have to pass customerGuid as queryString parameter like http://localhost:61374/api/values?customerGuid=D09584F2-0B81-4855-8F33-567F4EF8096C Then you can fetch query string value in action filter as:

  public class CustomFilter : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        var queryStringValues = actionContext.Request.GetQueryNameValuePairs();
        var customerGuid = queryStringValues.FirstOrDefault(x => x.Key == "customerGuid").Value;
        //Your logic
    }
}

Now there is no need to specify params in API method

public IHttpActionResult GetDetails()
{
  //Do stuff
}

answered Mar 30, 2017 at 9:53

Jignesh Variya

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