graphql-composer-decorators

# InterfaceType

A InterfaceType corresponds to the statement: interface with GraphQL (in SDL).

@InterfaceType()
class User {
  @Field()
  email: string;

  @Field()
  username: string;
}

Will give in SDL:

User interface {
  email: String
  username: String
}

# Parameters

@InterfaceType has several signatures available for setting up your object:

# name

Indicates the name of the type compiled in SDL.

# params

An object accepting several parameters:

Property description type
hidden The class will not be compiled and will not appear in the schema (useful for generic types), an abstract class is normally hidden boolean
nullable All fields of type will be nullable boolean
required All fields of the type will be required boolean
typeResolver Function determining the value of __typename GraphQLTypeResolver
description The description of the type string
extensions Extensions (metadata) of the type any
directives directives of the type {name: string, args: KeyValue}[]
extends Apply forced inheritance (ClassType | ObjectType | InterfaceType | InputType)[] (A class or a type declared with graphql-composer)[]

# @InterfaceField

The @InterfaceField decorator will show field parameters only for @InterfaceType.

This is useful when you use a class as several GraphQL types (``type,inputand/orinterface), decorating it simultaneously with@InterfaceTypeand@InputType` for example.

Because @Field sets the field for all GraphQL types whose class is decorated.

@InterfaceField overrides the parameters of @Field.

@InterfaceField()
@InputType("UserInput")
class User {
  @Field(type => R(String))
  @InterfaceField()
  username: string;

  @InputField(type => R(String))
  @InterfaceField()
  name: string;

  @Field()
  email: string;

  @InputField()
  password: string;
}

Will give in SDL:

User interface {
  username: String;
  name: String;
  email: Thong;
}

input UserInput {
  username: String!;
  name: String!;
  email: Thong;
  password: String;
}

# The function of TypeResolver (__typename)

By default a function that works with all types is written by graphql-composer, so in many cases you don't need to give a value to params.typeResolver.

The default function determines the type via the object properties, but generally for any object. This also applies to UnionType'. AGraphQLTypeResolver` function may look like this (in one specific case):

function typeResolver = (obj, context, info) => {
  if(obj.name){
    return "Author";
  }

  if(obj.title){
    return "Book";
  }

  return null;
}

@InterfaceType({
  typeResolver
})
class User {
  Field()
  username: string;
}

← Union type →