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Graph Controller

✅ See the section on Controllers & Actions for a detailed explination on how action methods work and how to declare them.

The GraphController, from which all of your controllers inherit, is a core object used throughout graphql. This page details some lesser known and lesser used object referenced made available to each controller.

ModelState​

The completed model state dictionary contains an entry for each validated parameter.

public class CharacterController : GraphController
{
    [Query]
    public IGraphActionResult CreateCharacter(Character characterModel)
    {
        if(!this.ModelState.IsValid)
            return this.BadRequest(this.ModelState);

        //...
    }
}

Request​

The field request generated via the execution pipeline. It contains all the necessary information used by graphql to resolve the current field.

public class CharacterController : GraphController
{
    [Query]
    public IGraphActionResult Hero(Episode episode = Episode.EMPIRE)
    {
        if(this.Request.Field.IsLeaf)
        {
            // ...
        }
    }
}

Notable Items on the Request​

  • Request.Field: A reference to the graph field definition, on the target schema, for the field currently being resolved.

    • .TypeExpression: The type expression describing the return value of this field
    • .IsLeaf: Indicates whether this field returns a leaf value (enum or scalar) or an object.
    • .Mode: Indicates the processing mode of this field (Batch or "per item")
    • .FieldSource: Indicates what member type generated the field; property, method, action etc.
    • .DataSource: The source data item being supplied to the field to be resolved.

  • Request.Items: A collection of key/value pairs accessible to all fields and directives in this individual request pipeline.

User​

The User property contains the ClaimsPrincipal created by ASP.NET when this request was authorized. 

public class CharacterController : GraphController
{
    [Query]
    public IGraphActionResult Hero(Episode episode = Episode.EMPIRE)
    {
        if(this.User.Identity.Name == "DebbieEast")
        {
            // ...
        }
    }
}

See the section on authorization for more details on how users are authenticated and authorized to action methods.

Schema​

The Schema property contains a reference to the singleton instance of the schema the current controller is resolving a field for. This object is considered read-only and should not be modified.

public class CharacterController : GraphController
{
    [Query]
    public IGraphActionResult Hero(Episode episode = Episode.EMPIRE)
    {
        IObjectGraphType droidType = this.Schema.KnownTypes.FindGraphType(typeof(Droid), TypeKind.OBJECT);
        // ...
    }
}