C# / ASP.NET Core Web API : how to pass a list parameter?

Question

I'm trying to pass a list parameter to an ASP.NET Core 5 Web API.

Here is my endpoint:

[ApiController]
[Route("[controller]")]
public class InvoiceController : ControllerBase
{
 private readonly IConfiguration _configuration;
 public InvoiceController(IConfiguration configuration)
 {
 _configuration = configuration;
 }
 [HttpPost]
 public List<CustomerInvoice> Post(string[] CustomerNumbers, DateTime OrderDateFrom, DateTime OrderDateTo)
 {
 }
}

Sending json post request fails with this error:

The JSON value could not be converted to System.String[]. Path: $ | LineNumber: 0 | BytePositionInLine: 1.

and here is the request:

{
 "CustomerNumbers": ["test"],
 "OrderDateFrom": "2021年01月01日",
 "OrderDateTo": "2021年11月02日"
}

Instead of using a string array, I also tried List<string>. I got the same error.

Any idea why the framework does not understand how to receive a list?

• ChiefTwoPencils: What's the JSON value look like?

Answer 1

You should create a class and receive JSON with this class. This may solve your problem.

public class ClassExample
{
 public List<string> CustomerNumbers { get; set; }
 public DateTime OrderDateFrom { get; set; }
 public DateTime OrderDateTo { get; set; }
}
[HttpPost]
public List<CustomerInvoice> Post(ClassExample requestParameter)
{
}

• max: Great. This does work. Thanks. My comment documentations do not appear in swagger with this approach. Do you know if there is a documentation on this?