Passing a json array to a REST Web API-CodePudding

This is a 2 part question.

I would like to pass an array of int values to my REST url but I'm getting an inline constraint exception. The route I tried to defined is as follows

[Route("categories/{categoryId:int}/documenttypes/{documentTypes:int[]}")]

...
...

and when called, it would look like this:

   api/categories/2/documenttypes/{[2,3,4,5]}

Can anyone point me in the right direction on how to handle this in-line constraint exception. I have found a few articles but none seem to apply on how to handle an array of int values.

Maybe it is not do-able and I should just change this to a POST request but I thought I'd try it with a GET first or just use the string parameter and just add another resource definition to my REST url such as

   api/config/categories/2/documenttypes/multi?doctype={[1,3,4]}

Is this event acceptable in terms of REST standards?
```
api/categories/2/documenttypes/{[1,3,4]}
```

I know I could just pass it as a query string but the problem I have with that is that I ended up with 2 endpoints conflicting if I do this:

    api/categories/2/documenttypes

no parameters and returns all document types for the given category

    api/categories/2/documenttypes?doctypes={[1,2,3]}

When defined and then called, I get an error that there are multiple end point with the same definition, thus the request to see if I could somehow pass it as an inline contraint.

Hope the above makes sense. If not, ask away. Thanks

CodePudding user response：

assuming the action is

[HttpGet("~/api/categories/{id}/documenttypes")]
public ActionResult GetDocTypes(int id, int[] doctype)

use this url

api/categories/2/documenttypes?doctype=2&doctype=3&doctype=4&doctype=5

CodePudding user response：

I figured out the various parts that needed to be changed.

First, I had to add a new route constraint (IHttpRouteConstraint) to handle the new data type passed as part of the Web API REST resource:

 public class HttpRouteConstraintIntArray : IHttpRouteConstraint
 {
      public bool Match(HttpRequestMessage request, IHttpRoute route,
        string parameterName, IDictionary<string, object> values,
        HttpRouteDirection routeDirection)
      {
          object value;
          if (values.TryGetValue(parameterName, out value) && value != null)
          {
              var parameters = value.ToString()
                  .Replace("{", string.Empty)
                  .Replace("}", string.Empty)
                  .Replace("[", string.Empty)
                  .Replace("]", string.Empty);
              var type = typeof(int);
              var newvalues = parameters.Split(new[] { "," },
               StringSplitOptions.RemoveEmptyEntries)                 
              .Select(TypeDescriptor.GetConverter(type)
              .ConvertFromString).ToArray();

              var typedValues = Array.CreateInstance(type, newvalues.Length);

              newvalues.CopyTo(typedValues, 0);

              return true;    
          }

          return false;
      }
 }

Once I declared this new constraint, I also had to register it in the WebApiConfig.cs:

        var constraintResolver = new DefaultInlineConstraintResolver();
        constraintResolver.ConstraintMap.Add("intarray", 
           typeof(HttpRouteConstraintIntArray));

config.MapHttpAttributeRoutes(constraintResolver);

But once I made these stanges, I started to get another error:

    the request contains an entity body but no Content-Type header
    get request ....

In order to resolve this error, I had to add [FromUri] in the endpoint definition:

[HttpGet]  [Route("categories/{categoryId:int}/documenttypes/
           {documentTypeIds:intarray}")]
 public async Task<IHttpActionResult> GetDataByDocumentTypeIds(
 int categoryId,[FromUri] int[] documentTypeIds)

Now the above is getting passed these 2 errors but some reason, the documentTypeIds is coming back as an array, but it only contains one value instead of 3 for example and its value is 0 instead of 1, so clearly need to add something else.

To handle the last problem, I had to create an action filter attribute:

 public class ArrayInputAttribute : ActionFilterAttribute
 {
 private readonly string[] _parameternames;

 public string Separator { get; set; }

 public ArrayInputAttribute(params string[] parameternames)
 {
     this._parameternames = parameternames;
     Separator = "-";
 }

 public void ProcessArrayInput(HttpActionContext actionContext, string parametername)
 {
     if (actionContext.ActionArguments
           .ContainsKey(parametername))
     {
         var parameterdescriptor = actionContext.ActionDescriptor.GetParameters()
             .FirstOrDefault(p => p.ParameterName == parametername);

         if (parameterdescriptor != null && parameterdescriptor.ParameterType.IsArray)
         {
             var type = parameterdescriptor.ParameterType.GetElementType();
             var parameters = string.Empty;
             if (actionContext.ControllerContext.RouteData.Values
                   .ContainsKey(parametername))
             {
                 parameters = (string)actionContext.ControllerContext
                   .RouteData.Values[parametername];
             }
             else
             {
                 var queryString = actionContext.ControllerContext
                    .Request.RequestUri.ParseQueryString();
                 if (queryString[parametername] != null)
                 {
                     parameters = queryString[parametername];
                 }
             }

             parameters = parameters.ToString()
                 .Replace("{", string.Empty)
                 .Replace("}", string.Empty)
                 .Replace("[", string.Empty)
                 .Replace("]", string.Empty);

             var values = parameters.Split(new[] { Separator },
                StringSplitOptions.RemoveEmptyEntries)
                Select(TypeDescriptor.GetConverter(type).
                ConvertFromString).ToArray();

             var typedValues = Array.CreateInstance(type, values.Length);

             values.CopyTo(typedValues, 0);

             actionContext.ActionArguments[parametername] = typedValues;
         }
     }
 }

 public override void OnActionExecuting(HttpActionContext actionContext)
 {
     foreach (var parameterName in _parameternames)
     {
         ProcessArrayInput(actionContext, parameterName);
     }
 }
}

and lastly, I had to add the attribute to the endpoint definition:

    [HttpGet]
    [Route("categories/{categoryId:int}/documenttypes/
            {documentTypeIds:intarray}")]
    [ArrayInputAttribute("documentTypeIds", Separator = ",")]
    public async Task<IHttpActionResult> GetDataByDocumentTypeIds(int categoryId,
    [FromUri] int[] documentTypeIds)
    {
    }

A few notes:

Some of the lines were split in order to be displayed semi decently in stackoverflow and clearly will not work in .NET studio
The above code was a combination of a couple of articles I eventually found after more googling. These are:

-Pass an array of integers to ASP.NET Web API?

By the looks of things, I may not even need to Constraint, thought right now I don't have time to investigate as I need to move on, I will post an update when I do try it later.

Web API Attribute Routing Route Constraints

Web API Attribute Routing Route Constrains

Hope the above helps others.

Thanks.