I have this controller method
//[HttpGet("{id}")]
public IActionResult Nav(string id)
{
return HtmlEncoder.Default.Encode($"Hello {id}");
//return Content("Here's the ContentResult message.");
}
that i want to pass a string parameter and display it when i visit the controller method https://localhost:7123/Home/Nav/Logan. I get this error.
Cannot implicitly convert type 'string' to 'Microsoft.AspNetCore.Mvc.IActionResult'
I am using asp net core 6.
It is throwing this error as you are returning a string when it expects an IActionResult. You can easily solve this by returning Ok($"Hello {id}");
Let me explain.
When you perform following action.
return HtmlEncoder.Default.Encode($"Hello {id}");
This will return string and your method expect IActionResult so it get failed.
Solution 1
public string Nav(string id)
{
return HtmlEncoder.Default.Encode($"Hello {id}");
}
Now if you two paramter then you have to configure route that way. Default route only expect one Id.
[HttpGet("Nav/{id}/{two}")]
public string Nav(string id,string two)
{
return HtmlEncoder.Default.Encode($"Hello {id},{two}");
}
Solution 2
You can use Content or Ok Result and provide your output.
public IActionResult Nav(string id)
{
return Ok(HtmlEncoder.Default.Encode($"Hello {id}"));
}
I fixed it this way. This is the url https://localhost:7123/Home/Nav/6?num=5&third=3
and this is the method
public IActionResult Nav(string id, int num, string third)
{
return Ok($"Hello {id} {num} {third}");
}
Related
It seems that the HttpGet method's return type need not be an ActionResult. For example, the following method works:
[HttpGet]
[Route("list")]
public async Task<IEnumerable<MyItem>> List()
But then, how can I return a BadRequest (BadRequest("...")) in this case?
If you really have to respond with BadRequest from within the controller method, you can use the following approach as recommended by Microsoft here
[HttpGet("list")]
[ProducesResponseType(StatusCodes.Status200OK, Type = typeof(IEnumerable<MyItem>))]
[ProducesResponseType(StatusCodes.Status400BadRequest)]
public async IActionResult List()
{
// Code to validate request
if(requestIsValid)
{
// Code to get IEnumerable of MyItems
return Ok(myItems);
}
else
{
return BadRequest()
}
}
I try to trigger a specific method (the second one) in HeroesController class:
[HttpGet]
public IEnumerable<Hero> Get()
{
return Heroes;
}
[HttpGet("/name={term}")]
public IEnumerable<Hero> Get(string term)
{
return Heroes;
}
After calling this URL:
https://localhost:44375/heroes/?name=Spider
The first method is triggered, not the second. Why is that so? How to trigger the second one which receives term parameter?
As pointed out in the comments by King King, the url is not matched, but the best way to do this is;
[HttpGet]
public IEnumerable<Hero> Get([FromQuery] string term)
{
return Heroes;
}
Then the endpoint would be hit if a query parameter, term is passed https://localhost:44375/heroes?term=Spider
There are 2 things to distinguish here - URL parameters versus query parameters. If you want to supply variable while doing you GET HTTP call these are the options:
Variable you want to pass can be part of the URL:
http://localhost:8080/yourResourceName/{varValue}
[HttpGet]
public Task<IActionResult> Get(string varValue)
{
}
Variable you want to pass can be a query parameter:
http://localhost:8080/yourResourceName?varname={varValue}
[HttpGet]
public Task<IActionResult> Get([FromQuery]string varValue)
{
}
I have two methods:
[HttpGet("{id}")]
public IActionResult GetTask([FromRoute] int id)
{
}
[HttpGet("{userId}")]
public IActionResult GetUserTask([FromRoute] string userId)
{
}
As you can see, i want to pass to my API routes like:
https://localhost:44365/Task/1
and
https://localhost:44365/Task/string
But my WebApi project cant handle it. When i pass route like this:
https://localhost:44365/Task/7dd2514618c4-4575b3b6f2e9731edd61
i get an 400 http and this response:
{
"id": [
"The value '7dd2514618c4-4575b3b6f2e9731edd61' is not valid."
]
}
While debugging, im not hitting any methods (when i pass string instead of int)
My question is, how to verload methods with one parameters with string or int? These methods do diffrent things
EDIT
When i pass something like:
https://localhost:44365/Task/dddd
I still get response with invalid id
You can define parameter type like [HttpGet("{id:int}")]. For more information refer below link.
https://learn.microsoft.com/en-us/aspnet/web-api/overview/web-api-routing-and-actions/attribute-routing-in-web-api-2#route-constraints
Your actions should be like below.
[HttpGet("{id:int}")]
public IActionResult GetTask([FromRoute] int id)
{
}
[HttpGet("{userId}")]
public IActionResult GetUserTask([FromRoute] string userId)
{
}
Use like this
[HttpGet("{id}")]
public IActionResult GetTask([FromRoute] int id)
{
}
[HttpGet("User/{userId}")]
public IActionResult GetUserTask([FromRoute] string userId)
{
}
and while calling api with guid/string use
https://localhost:44365/Task/User/7dd2514618c4-4575b3b6f2e9731edd61
I tried to call the update web api on Postman but it seems that it doesn't pass the id param to the asp.net core controller (asp.net core 2.0)
public class ShoppingCartController : BaseController
{
[HttpPut("{id}")]
[Route("api/ShoppingCart/UpdateShoppingCartItem")]
public IActionResult UpdateShoppingCartItem(long id)
{
return new NoContentResult();
}
}
You have to use [FromBody].
[HttpPut("{id}")]
[Route("api/ShoppingCart/UpdateShoppingCartItem")]
public IActionResult UpdateShoppingCartItem([FromBody]long id)
{
return new NoContentResult();
}
In Postman you must use a simple number.
Replace:
{
"id":87908908
}
with
87908908
Default behaviour of param parsing: From Url.
Use [FromBody] before your method param to let asp parse this param from the Body.
Can you try changing method UpdateShoppingCartItem to the following:
public IActionResult UpdateShoppingCartItem([FromBody] long id)
HttpPut now accepts the route as parameter, so you can combine your attributes.
public class ShoppingCartController : BaseController
{
[HttpPut("api/ShoppingCart/UpdateShoppingCartItem")]
public IActionResult UpdateShoppingCartItem(long id)
{
return new NoContentResult();
}
}
The model binder should infer the value of id from the body.
Using [HttpPut("{id}")] would mean that a put request to localhost:44342/65465 would be a valid action.
I am using MVC 4, and I have the following:
[HttpGet]
public ActionResult SomeForm(modelType model = null)
{
if(model != null)
return View(model);
return View(getModelFromSomewhere());
}
[HttpPost]
public ActionResult SomeForm(modelType model)
{
if(isValid())
doSomething();
else
return SomeForm(model) // Line in Question
}
However, obviously, I am getting an ambiguous method error on "Line in Question". I'm wondering if anyone has an elegant solution to be able to specify to return specifically the [Get] method of the same name?
Thank you!
You can't have methods with the same signature as you've pointed out already. In C# it also means you can't distinguish functions by just return type - so you must use different names if parameters are same (again default values are ignored when matching of signatures).
If you want separate GET and POST handler - use different names of methods and ActionNameAttribute to name the action:
[HttpGet]
[AciontName("SomeForm")]
public ActionResult SomeFormGet(modelType model = null) ...
[HttpPost]
[AciontName("SomeForm")]
public ActionResult SomeFormPost(modelType model) ...
make it compile...
[HttpPost]
public ActionResult SomeForm(modelType model, FormCollection fc)
{
if(isValid())
doSomething();
else
return SomeForm(model) // Line in Question
}
If you are using http get method you are waiting that browser will send you serialized model as a string query. For example, you are waiting url like
http://example.com?name=Andrew&type=Worker&field1=param1&field2=param2&....
It is common practice to use only id in your get method, so you can do it like this:
[HttpGet]
public ActionResult SomeForm(int id)
{
var model = FindModelById(id);
if(model != null)
return View(model);
return View(getModelFromSomewhere());
}
If you are looking for an elegant solution, it will be more elegant in architecture