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

I have an ASP.NET Web API (version 4) REST service where I need to pass an array of integers.

Here is my action method:

public IEnumerable<Category> GetCategories(int[] categoryIds){
// code to retrieve categories from database
}

And this is the URL that I have tried:

/Categories?categoryids=1,2,3,4

Solution 1:

You just need to add [FromUri] before parameter, looks like:

GetCategories([FromUri] int[] categoryIds)

And send request:

/Categories?categoryids=1&categoryids=2&categoryids=3 

Solution 2:

As Filip W points out, you might have to resort to a custom model binder like this (modified to bind to actual type of param):

public IEnumerable<Category> GetCategories([ModelBinder(typeof(CommaDelimitedArrayModelBinder))]long[] categoryIds) 
{
    // do your thing
}

public class CommaDelimitedArrayModelBinder : IModelBinder
{
    public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext)
    {
        var key = bindingContext.ModelName;
        var val = bindingContext.ValueProvider.GetValue(key);
        if (val != null)
        {
            var s = val.AttemptedValue;
            if (s != null)
            {
                var elementType = bindingContext.ModelType.GetElementType();
                var converter = TypeDescriptor.GetConverter(elementType);
                var values = Array.ConvertAll(s.Split(new[] { ","},StringSplitOptions.RemoveEmptyEntries),
                    x => { return converter.ConvertFromString(x != null ? x.Trim() : x); });

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

                values.CopyTo(typedValues, 0);

                bindingContext.Model = typedValues;
            }
            else
            {
                // change this line to null if you prefer nulls to empty arrays 
                bindingContext.Model = Array.CreateInstance(bindingContext.ModelType.GetElementType(), 0);
            }
            return true;
        }
        return false;
    }
}

And then you can say:

/Categories?categoryids=1,2,3,4 and ASP.NET Web API will correctly bind your categoryIds array.

Solution 3:

I recently came across this requirement myself, and I decided to implement an ActionFilter to handle this.

public class ArrayInputAttribute : ActionFilterAttribute
{
    private readonly string _parameterName;

    public ArrayInputAttribute(string parameterName)
    {
        _parameterName = parameterName;
        Separator = ',';
    }

    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        if (actionContext.ActionArguments.ContainsKey(_parameterName))
        {
            string parameters = string.Empty;
            if (actionContext.ControllerContext.RouteData.Values.ContainsKey(_parameterName))
                parameters = (string) actionContext.ControllerContext.RouteData.Values[_parameterName];
            else if (actionContext.ControllerContext.Request.RequestUri.ParseQueryString()[_parameterName] != null)
                parameters = actionContext.ControllerContext.Request.RequestUri.ParseQueryString()[_parameterName];

            actionContext.ActionArguments[_parameterName] = parameters.Split(Separator).Select(int.Parse).ToArray();
        }
    }

    public char Separator { get; set; }
}

I am applying it like so (note that I used 'id', not 'ids', as that is how it is specified in my route):

[ArrayInput("id", Separator = ';')]
public IEnumerable<Measure> Get(int[] id)
{
    return id.Select(i => GetData(i));
}

And the public url would be:

/api/Data/1;2;3;4

You may have to refactor this to meet your specific needs.

Solution 4:

In case someone would need - to achieve same or similar thing(like delete) via POST instead of FromUri, use FromBody and on client side(JS/jQuery) format param as $.param({ '': categoryids }, true)

c#:

public IHttpActionResult Remove([FromBody] int[] categoryIds)

jQuery:

$.ajax({
        type: 'POST',
        data: $.param({ '': categoryids }, true),
        url: url,
//...
});

The thing with $.param({ '': categoryids }, true) is that it .net will expect post body to contain urlencoded value like =1&=2&=3 without parameter name, and without brackets.

Solution 5:

Easy way to send array params to web api

API

public IEnumerable<Category> GetCategories([FromUri]int[] categoryIds){
 // code to retrieve categories from database
}

Jquery : send JSON object as request params

$.get('api/categories/GetCategories',{categoryIds:[1,2,3,4]}).done(function(response){
console.log(response);
//success response
});

It will generate your request URL like ../api/categories/GetCategories?categoryIds=1&categoryIds=2&categoryIds=3&categoryIds=4