Pass Array into ASP.NET Core Route Query String

Question

I want to do this, but I want to also be able to pass in arrays into the query string. I've tried things like:

http://www.sitename.com/route?arr[]=this&arr[]=that
http://www.sitename.com/route?arr[]=this&that
http://www.sitename.com/route?arr[0]=this&arr[1]=that
http://www.sitename.com/route?arr0=this&arr1=that
http://www.sitename.com/route?arr=this&arr=that

And my route in the C# code looks like this:

[Route("route")]
[HttpGet]
public void DoSomething(string[] values)
{
    // ...
}

But in all of these cases, values is always null when it gets to the C# code. What do I need my query string to be to pass an array of strings?

Answer 1

Use a parameter name in the query string. If you have an action:

public void DoSomething(string[] values)

Then use values in the query string to pass an array to a server:

?values=this&values=that

Answer 2

Delimited string is not the standard. Think also about the client if you support swagger or other generators.

For those who wonder about .net core 2.1 bug which receives an empty list, the work around is here: https://github.com/aspnet/Mvc/issues/7712#issuecomment-397003420

It needs a name parameter on FromQuery

[FromQuery(Name = "employeeNumbers")] List<string> employeeNumbers

Answer 3

I have found a solution. For example, if you have a query like this:

http://www.sitename.com/route?arr[]=this&arr[]=that

You must define in parameter as [FromQuery(Name = "arr[]")]. The name of parameter must include square brackets. As result we can see:

public void DoSomething([FromQuery(Name = "arr[]")] string[] arr)