为什么 nameof 不适用于 CreationAtAction 返回语句

Question

I am developing a Web API using .NET Core ,when I send a post or an update to my web api, I am returning the resource. For that, at the end of each method, I am using CreatedAtAction method, where the first parameter is the action name.

When I am using a hard coded action name, CreatedAtAction("GetBook", [...] for example, it works. But when I am using CreatedAtRoute(nameof(GetBook), [...] I got an error saying that no routes matches. Is there a particulary reason for that ?

Answer 1

Look like you've mixed up the CreatedAt*Action* and CreatedAt*Route* methods. nameof(GetBook) should definitely return "GetBook" .

Answer 2

请参阅此链接： https : //docs.microsoft.com/en-us/aspnet/core/web-api/? view = aspnetcore -2.2 它显示CreatedAtAction (nameof(GetBook), [...]) 应该可以工作。

Answer 3

The CreatedAtRoute is a helper method which inherits from ControllerBase . What CreatedAtRoute() does is simply returning a new CreatedAtRouteResult(routeName, routeValues, value) . There is no dark magic at all :

/// <summary>
/// Creates a <see cref="CreatedAtRouteResult"/> object that produces a <see cref="StatusCodes.Status201Created"/> response.
/// </summary>
/// <param name="routeName">The name of the route to use for generating the URL.</param>
/// <param name="routeValues">The route data to use for generating the URL.</param>
/// <param name="value">The content value to format in the entity body.</param>
/// <returns>The created <see cref="CreatedAtRouteResult"/> for the response.</returns>
[NonAction]
public virtual CreatedAtRouteResult CreatedAtRoute(string routeName, object routeValues, object value)
=> new CreatedAtRouteResult(routeName, routeValues, value);

The CreatedAtRoute method is often used within a ApiController , and the third parameter will be used as the content of response . Let's say an action method :

[Route("api/[controller]")]
[ApiController]
public class ValuesController : ControllerBase
{
    
    [HttpGet("{id}", Name = "HelloDetails")]
    public IActionResult GetDetail(int id)
    {
        var result = new MyItem() {
            Id=id,
            ItemName="sherry"
        }; 
        
        return new JsonResult(result);
    }

    [HttpPost]
    public async Task<IActionResult> Create([FromBody] MyItem item)
    {
        if (item == null)
        {
            return BadRequest();
        }
        
        return CreatedAtRoute("HelloDetails", new { id = item.Id }, item);
    }

Use Postman to test ,the result is a 201 response. The response's body contains details of the entity we created and the response's Location header contains a URI to the entity.

You could also have a look at this link