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c#web-servicesasp.net-web-api2
Osama AbuSitta
Osama AbuSitta

Reputation: 4066

How I can read parameter value from controller constructor in asp.net web API 2?

How I can read parameter value from controller constructor in asp.net web API 2 ??

 public class DataController : ApiController
{
    private APIMgr apiMgr ; // APIMgr custome class 

    public DataController()
    {
       // var id = Request.GetRouteData(); = 5 // this parameter must send with alla request "http://localhost/TAPI/api/data/5"
        apiMgr= new apiMgr(id);
    }

Upvotes: 2

Views: 4546

Answers (3)

Osama AbuSitta
Osama AbuSitta

Reputation: 4066

The HttpContext is not set when the controller class is constructed , but it set ("injected") later by the ControllerBuilder class .
According to this I can to access the HttpContext by override "Initialize" method . This page explains ASP.NET MVC request flow

  protected override void Initialize(HttpControllerContext controllerContext)
    {
        base.Initialize(controllerContext);
    }

Upvotes: 3

ceej
ceej

Reputation: 1893

You can't. To read parameter values in action methods there are a few ways. Let us assume a model that represents a person.

public class Person
{
    public Guid Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

Now let us assume that we with to have an API method that enables us to send a representation of a person to the server that will then save it to some data store. For this purpose we implement a POST method that accepts parameters to build our person object. There are a few ways we could do this.

Method 1: Bind parameters from the request body

public IHttpActionResult Post([FromBody]Person person)
{
    // validate your parameter in some way
    if (person.Equals(default(Person))) return BadRequest("person must not be null");
    // go off and save the person
    var createdPerson = myPersonRepository.Save(person);
    if (createdPerson == default(Person)) return InternalServerError();
    return CreatedAtRoute("DefaultApi", new { id = createdPerson.Id }, createPerson);
}

This requires you to pass a JSON representation of your person in the request body. Something like the following should do it.

{
    "firstname": "Luke",
    "lastname": "Skywalker"
}

Method 2: Bind parameters from the request URL query string

public IHttpActionResult Post([FromUri]Person person)
{
    // validate your parameter in some way
    if (person.Equals(default(Person))) return BadRequest("person must not be null");
    // go off and save the person
    var createdPerson = myPersonRepository.Save(person);
    if (createdPerson == default(Person)) return InternalServerError();
    return CreatedAtRoute("DefaultApi", new { id = createdPerson.Id }, createPerson);
}

This requires you to pass the parameter values in the query string, for example:

http://mywhizzyapi/api/people?firstname=luke&lastname=skywalker

Method 3: Explicitly pass parameters and create the object yourself

public IHttpActionResult Post(string firstname, string lastname)
{
    // validate your parameter in some way
    if (id.Equals(Guid.Empty)) return BadRequest("id must not be null or an empty GUID");
    if (string.IsNullOrEmpty(firstname)) return BadRequest("firstname must not be null or empty");
    if (string.IsNullOrEmpty(lastname)) return BadRequest("lastname must not be null or empty");
    // create your person object
    var person = New Person {
        id = id,
        firstName = firstname,
        lastname = lastname,
    };
    // go off and save the person
    var createdPerson = myPersonRepository.Save(person);
    if (createdPerson == default(Person)) return InternalServerError();
    return CreatedAtRoute("DefaultApi", new { id = createdPerson.Id }, createPerson);
}

This method also requires you to pass the parameter values in the query string, for example:

http://mywhizzyapi/api/people?firstname=luke&lastname=skywalker

But in the last case as mentioned you have to bind the parameters explicitly to your model.

Upvotes: 0

Spencer
Spencer

Reputation: 271

You cannot read route parameters from within a constructor...only from an action method. You'll need to define an appropriate route with expected templates. Take a look at the default controller in your route config in WebApiConfig.cs

Also HttpContext is not accessible from within a controller constructor.

Upvotes: 1

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