I have a method as described below which get user as parameter.
To send the user parameter values, I am using postman request/response tool.
My question is, if the request already have user parameter in body request (see at the postman print screen ) why do I need to directly specify [FromBody] in action controller? When this attribute removed, parameter send with null values.
Thanks
[HttpPost("register")]
public IActionResult Register([FromBody]User user)
{
//.. code here
}
public class User
{
public string Name { get; set; }
public string Password { get; set; }
}
The [FromBody] directive tells the Register action to look for the User parameter in the Body of the request, rather than somewhere else, like from the URL. So, removing that confuses your method, and that's why you see null values as it's not sure where to look for the User parameters.
See: https://learn.microsoft.com/en-us/aspnet/web-api/overview/formats-and-model-binding/parameter-binding-in-aspnet-web-api for more information/learning.
For Model Binding in ASP.NET Core, MVC and Web APi uses the same model binding pattern.
There are default model bindings like Form Values, Route values and Query Strings. If these bindings fails, it will not throw an error, and return null.
If you do not want to add [FromBody], you could try Form Values binding and send request from Postman like below:
[FromBody] will override default data source and specify the model binder's data source from the request body.
You could refer Model Binding in ASP.NET Core for detail information
the attribute [FromBody] ensures the API reads the JSON payload in the postman body. For more info, read
https://learn.microsoft.com/en-us/aspnet/web-api/overview/formats-and-model-binding/parameter-binding-in-aspnet-web-api
Related
I have the following WEB API method, and have a SPA template with Angular:
[HttpPost]
public IActionResult Post([FromBody]MyViewModel model)
I thought, based on this topic, there is no need to use [FromBody] here, since I want to read the value from the message body, so there is no need to override the default behavior, but, if I don't use [FromBody], the model that is coming from Angular is null. I'm really confused, why should I use [FromBody], since I have used the default behavior?
For anyone seeing this issue .net core 3 - you need to add the [ApiController] to the controller where you extend ControllerBase.
The [FromBody] is only needed if you're doing an MVC controller.
This causes the body to get automatically processed in the way you're expecting.
Microsoft documentation for the ApiController attribute
The question you linked to is referring to web-api. You are using core-mvc which has been re-written to merge the pipelines for the previous mvc and web-api versions into one Controller class.
When posting json (as apposed to x-www-form-urlencoded), the [FromBody] attribute is required to instruct the ModelBinder to use the content-type header to determine the IInputFormatter to use for reading the request.
For a detailed explanation of model binding to json in core-mvc, refer Model binding JSON POSTs in ASP.NET Core.
And here's an alternate approach assuming you need to support both [FromForm] and [FromBody] in your Controller API…
Front-End (Angular Code):
forgotPassword(forgotPassword: ForgotPassword): Observable<number> {
const params = new URLSearchParams();
Object.keys(forgotPassword).forEach(key => params.append(key, forgotPassword[key]));
return this.httpClient.post(`${this.apiAuthUrl}/account/forgotpassword`, params.toString(), { headers: { 'Content-Type': 'application/x-www-form-urlencoded' } });
}
Back-End (C# Code):
[AllowAnonymous]
[HttpPost("[action]")]
public async Task<IActionResult> ForgotPassword(ForgotPasswordViewModel model) { }
Now your signature can remain the same so it can support both.
And another more permanent approach I thought about while addressing.
https://benfoster.io/blog/aspnet-core-customising-model-binding-conventions.
Hope it helps someone!
See my discussion https://stackoverflow.com/a/75263628/5555938 on [FromBody]. It explains everything in great detail!
But in summary, [FromBody] does NOT accept HTML Form field name-value pairs like [FromForm]. It does NOT accept a traditional HTML form submission! It requires the following:
JavaScript POST Request manually sent to the Web API server
JavaScript Http Header with JSON mime-type attached
JavaScript Http Body with form field extracted data, reformatted and submitted as JSON. Traditional HTML POST name-value pairs will not work!
I have a .net Core 2 API setup with some test function. (Visual Studio 2017)
Using postman I do a post with the raw data to that method, but the model is just blank? Why?
// POST api/Product/test
[HttpPost]
[Route("test")]
public object test(MyTestModel model)
{
try
{
var a = model.SomeTestParam;
return Ok("Yey");
}
catch (Exception ex)
{
return BadRequest(new { message = ex.Message });
}
}
public class MyTestModel
{
public int SomeTestParam { get; set; }
}
You need to include the [FromBody] attribute on the model:
[FromBody] MyTestModel model
See Andrew Lock's post for more information:
In order to bind the JSON correctly in ASP.NET Core, you must modify your action to include the attribute [FromBody] on the parameter. This tells the framework to use the content-type header of the request to decide which of the configured IInputFormatters to use for model binding.
As noted by #anserk in the comments, this also requires the Content-Type header to be set to application/json.
To add more information to the accepted answer:
There are three sources from which parameters are bound automatically without the use of an Attribute:
Form values: These are form values that go in the HTTP request using
the POST method. (including jQuery POST requests).
Route values: The set of route values provided by Routing
Query strings: The query string part of the URI.
Note that Body is NOT one of them (though I think it should be).
So if you have values that need to be bound from the body, you MUST use the attribute binding attribute.
This tripped me up yesterday as I assumed that parameters from the Body would be bound automatically.
The second minor point is that only one parameter can be bound to the Body.
There can be at most one parameter per action decorated with [FromBody]. The ASP.NET Core MVC run-time delegates the responsibility of reading the request stream to the formatter. Once the request stream is read for a parameter, it's generally not possible to read the request stream again for binding other [FromBody] parameters.
Thus if there is more than one parameter you need, you need to create a Model class to bind them:
public class InputModel{
public string FirstName{get;set;}
public string LastName{get;set;}
}
[HttpPost]
public IActionResult test([FromBody]InputModel model)...
The Docs
Alternatively, add the [ApiController] attribute to your controller.
This has annoyingly affected me so many times (months apart) that I want this answer visible.
I deal with this issue for some hours. This problem stems from several reasons. Let's consider the request is Reactjs (javascript) and backend (API) is Asp .Net Core.
in the request, you must set in header Content-Type:
Axios({
method: 'post',
headers: { 'Content-Type': 'application/json'},
url: 'https://localhost:44346/Order/Order/GiveOrder',
data: order,
}).then(function (response) {
console.log(response);
});
and in the backend (Asp .net core API) u must have some setting:
1. in Startup --> ConfigureServices:
#region Allow-Orgin
services.AddCors(c =>
{
c.AddPolicy("AllowOrigin", options => options.AllowAnyOrigin());
});
#endregion
2. in Startup --> Configure before app.UseMvc() :
app.UseCors(builder => builder
.AllowAnyOrigin()
.AllowAnyMethod()
.AllowAnyHeader()
.AllowCredentials());
3. in the controller before action:
[EnableCors("AllowOrigin")]
In my case I had { get; set; } missing in my .cs model which results in an object with all members null on POST.
I have a Web API action that looks like the following:
[HttpGet]
[Route("api/query/hello/{query}")]
public HttpResponseMessage Hello([FromUri]Query query)
{
return null;
}
where the Query class has a public string property named QueryText. When I hit the following URL, I get a 404 error:
/api/query/hello?QueryText=bacon
This worked before I started using Attribute Routing. If I have no parameters or primitive type parameters, I can get Attribute Routing to work. But with a complex parameter, I get 404s. How does Attribute Routing work with complex action parameters? Is it compatible with the FromUri attribute?
The solution here was that the {query} token in the Route definition was superfluous. Removing it, as follows, fixed the issue:
[Route("api/query/hello")]
The [FromUri] attribute will be needed because you're reading from the URL. Your route should look something like:
public HttpResponseMessage Hello([FromUri]Query query)
{
//Implement whatever
return null;
}
/api/{Controller Name}/hello?QueryText=bacon
Should then work correctly.
The model binder will take whatever query parameters you provided then try to bind whatever is inside that Query object. I'd worry about the Route Attribute after you've got it working first.
Since a few days I'm trying to create my own web api controller. Duo to the rest conventions I need to use a post request to create an object. To get concrete, Im having this controller with this action:
public class ReservationController : ApiController
{
[HttpPost]
public void Create(int roomId, DateTime arrivalDate)
{
//do something with both parameters
}
}
This code is not working when I fire a post request at it, I'm receiving a 404 exception something like this:
No action was found on the controller 'Some' that matches the request.
The reason for it is that simple types are read from the query string, complex types from the body, according to this aricle. The web api uses the parameters to match the action to a request and can't therefore map my action to the request.
I do know that I can use the [frombody] tag, but you can only apply that to one parameter and I have 2. I also know that I can create a wrapper object which have both the parameters, but I'm not willing to use wrappers for all my calls.
So I do know that I can work around this by these methods. I also think that this is caused by the fact that the body of the post request can only be read once. But my actual question is:
Why is the source of a parameter determined by it's type and not by it's availability, especially when the conventions state that you should make for example a post request for creation? In MVC this is the case, why isn't it in the web api?
Best regards,
BHD
FINAL UPDATE
Since I'm getting some upvotes, problably more people are facing the same question. In the end it comes to this: Web-Api != MVC. It's simply not the same thing and the web api team made different design decisions than the mvc team I guess.
It seems that you have a fundamental misunderstanding of how Web API actually works.
Web API routing is driven off of verbiage, not the method names. "SomeMethod" actually translates to zero useful information for Web API. As a result, if I post
api/some/some?id=1
OR
api/some/somemethod?id=1
OR EVEN
api/some/?id=1
and the SomeMethod endpoint is the ONLY available POST, it will hit that endpoint.
As such, first of all, make sure you have only one POST on that api controller. If you do, POSTing to it from any test client using either of the query strings above will work just fine.
You can use the [FromBody] attribute on the parameter to force it to read from the body of the HTTP POST instead of the Uri. This is opposed to the [FromUri] attribute which does the opposite.
[HttpPost]
public void SomeAction([FromBody] int id)
{
//do something with id
}
Are you sure you're actually putting the id in the body? It could also be a routing issue. If this still doesn't work then maybe you should use Fiddler and copy the RAW output of your HTTP message here.
If you're packing multiple values into the body such as with JSON then you should use a model which should automatically be deserialized to:
public class PostModel
{
public int ID { get; set; }
public int SomeOtherID { get; set; }
}
[HttpPost]
public void SomeAction(PostModel postModel)
{
//do something with postModel.ID and postModel.SomeOtherID
}
You can actually do this straight out of the box in WebAPI, at least in 2.2 (.Net version 4.5.2). Your controller is correct. Using your controller, if you call it with a HTTP POST like this (tested through Fiddler):
http://localhost:58397/api/Reservation?roomId=123&arrivalDate=2015-12-17
You'll get the correct values of roomId = 123 and arrivalDate = 17.12.2015.
I suspect there's something wrong in your call to the WebAPI. Maybe post that call if you're still not getting it to work.
I am testing a push notification on a calendar application. When I create an event on calendar application, my website gets a HttpPost request with a JSON string. I wrote code like this but I couldn't receive the JSON string in my action method.
[HttpPost]
public ActionResult Push(String jsonReq)
{
Console.write(jsonReq);
return View();
}
When I create model in the same structure as JSON, then I can receive the request. it seems to be tightly coupled to JSON structure ? I am using in ASP.Net MVC 4.
[HttpPost]
public ActionResult Push(JSONModel jsonModel)
{
return View();
}
ASP.NET MVC model binding works the following way - it parses the request, tries to find a name-to-name corresponding between its parameters and Action paramaters, and if found instantiates latter. You are not sending parameter with name jsonReq, so you cannot receive something in your action method.
If you really want to work with plan json string without letting ASP.NET MVC parse it for your, you have two options:
Access it via HttpContext.Request inside the action
Write custom model binder that will map the request body to the jsonReq parameter
The request would not have a value named jsonReq so would not know to map the json to that action parameter.
Where as your JSONModel will have property names that match the JSON named values coming into the request thus the object us populated.