Fixed all comments

@types/graphql-query-complexity/index.d.ts

@@ -0,0 +1,35 @@
+
+declare module "graphql-query-complexity" {
+    import {QueryComplexityOptions} from 'graphql-query-complexity/dist/QueryComplexity';
+    import QueryComplexity from 'graphql-query-complexity/dist/QueryComplexity';
+    import { ValidationContext } from 'graphql';
+    type returnType = (context: ValidationContext) => QueryComplexity ;
+    export default function createQueryComplexityValidator(options: QueryComplexityOptions): returnType;
+}
+declare module "graphql-query-complexity/dist/QueryComplexity" {
+    import { ValidationContext, FragmentDefinitionNode, OperationDefinitionNode, FieldNode, InlineFragmentNode } from 'graphql';
+    import { GraphQLUnionType, GraphQLObjectType, GraphQLInterfaceType, GraphQLError } from 'graphql';
+    export interface QueryComplexityOptions {
+        maximumComplexity: number;
+        variables?: Object;
+        onComplete?: (complexity: number) => void;
+        createError?: (max: number, actual: number) => GraphQLError;
+    }
+    export default class QueryComplexity {
+        context: ValidationContext;
+        complexity: number;
+        options: QueryComplexityOptions;
+        fragments: {
+            [name: string]: FragmentDefinitionNode;
+        };
+        OperationDefinition: Object;
+        constructor(context: ValidationContext, options: QueryComplexityOptions);
+        onOperationDefinitionEnter(operation: OperationDefinitionNode): void;
+        onOperationDefinitionLeave(): GraphQLError | undefined;
+        nodeComplexity(node: FieldNode | FragmentDefinitionNode | InlineFragmentNode | OperationDefinitionNode, typeDef: GraphQLObjectType | GraphQLInterfaceType | GraphQLUnionType, complexity?: number): number;
+        createError(): GraphQLError;
+        getDefaultComplexity(args: Object, childScore: number): number;
+    }
+
+}
+

examples/query-complexity/examples.gql

@@ -0,0 +1,15 @@
+
+query GetRecipesWithComplexityError {
+  recipes {
+    title
+    averageRating,
+    ratingsCount
+  }
+}
+
+mutation GetRecipesWithoutComplexityError {
+  recipes {
+    title
+    averageRating
+  }
+}

examples/query-complexity/index.ts

@@ -0,0 +1,46 @@
+import "reflect-metadata";
+import { GraphQLServer, Options } from "graphql-yoga";
+import { buildSchema } from "../../src";
+import queryComplexity from "graphql-query-complexity";
+import { RecipeResolver } from "./recipe-resolver";
+
+async function bootstrap() {
+  // build TypeGraphQL executable schema
+  const schema = await buildSchema({
+    resolvers: [RecipeResolver],
+  });
+
+  // Create GraphQL server
+  const server = new GraphQLServer({ schema });
+
+  // Configure server options
+  const serverOptions: Options = {
+    port: 4000,
+    endpoint: "/graphql",
+    playground: "/playground",
+    validationRules: req => [
+      /**
+       * This  provides GraphQL query analysis to reject complex queries to your GraphQL server.
+       * This can be used to protect your GraphQL servers
+       * against resource exhaustion and DoS attacks.
+       * More doucmentation can be found (here)[https://github.com/ivome/graphql-query-complexity]
+       */
+      queryComplexity({
+        maximumComplexity: 8,
+        variables: req.query.variables,
+        onComplete: (complexity: number) => {
+          console.log("Query Complexity:", complexity);
+        },
+      }),
+    ],
+  };
+
+  // Start the server
+  server.start(serverOptions, ({ port, playground }) => {
+    console.log(
+      `Server is running, GraphQL Playground available at http://localhost:${port}${playground}`,
+    );
+  });
+}
+
+bootstrap();

examples/query-complexity/recipe-input.ts

@@ -0,0 +1,11 @@
+import { Recipe } from "./recipe-type";
+import { InputType, Field } from "../../src";
+
+@InputType()
+export class RecipeInput implements Partial<Recipe> {
+  @Field()
+  title: string;
+
+  @Field({ nullable: true })
+  description?: string;
+}

examples/query-complexity/recipe-resolver.ts

@@ -0,0 +1,51 @@
+import {
+  Resolver,
+  Query,
+  FieldResolver,
+  Arg,
+  Root,
+  Mutation,
+  Float,
+  Int,
+  ResolverInterface,
+} from "../../src";
+import { plainToClass } from "class-transformer";
+
+import { Recipe } from "./recipe-type";
+import { RecipeInput } from "./recipe-input";
+import { createRecipeSamples } from "./recipe-samples";
+
+@Resolver(of => Recipe)
+export class RecipeResolver implements ResolverInterface<Recipe> {
+  private readonly items: Recipe[] = createRecipeSamples();
+
+  @Query(returns => Recipe, { nullable: true })
+  async recipe(@Arg("title") title: string): Promise<Recipe | undefined> {
+    return await this.items.find(recipe => recipe.title === title);
+  }
+
+  @Query(returns => [Recipe], { description: "Get all the recipes from around the world " })
+  async recipes(): Promise<Recipe[]> {
+    return await this.items;
+  }
+
+  @Mutation(returns => Recipe, { complexity: 10 })
+  async addRecipe(@Arg("recipe") recipeInput: RecipeInput): Promise<Recipe> {
+    const recipe = plainToClass(Recipe, {
+      description: recipeInput.description,
+      title: recipeInput.title,
+      ratings: [],
+      creationDate: new Date(),
+    });
+    await this.items.push(recipe);
+    return recipe;
+  }
+
+  @FieldResolver()
+  ratingsCount(
+    @Root() recipe: Recipe,
+    @Arg("minRate", type => Int, { nullable: true }) minRate: number = 0.0,
+  ): number {
+    return recipe.ratings.filter(rating => rating >= minRate).length;
+  }
+}

examples/query-complexity/recipe-samples.ts

@@ -0,0 +1,26 @@
+import { plainToClass } from "class-transformer";
+
+import { Recipe } from "./recipe-type";
+
+export function createRecipeSamples() {
+  return plainToClass(Recipe, [
+    {
+      description: "Desc 1",
+      title: "Recipe 1",
+      ratings: [0, 3, 1],
+      creationDate: new Date("2018-04-11"),
+    },
+    {
+      description: "Desc 2",
+      title: "Recipe 2",
+      ratings: [4, 2, 3, 1],
+      creationDate: new Date("2018-04-15"),
+    },
+    {
+      description: "Desc 3",
+      title: "Recipe 3",
+      ratings: [5, 4],
+      creationDate: new Date(),
+    },
+  ]);
+}

examples/query-complexity/recipe-type.ts

@@ -0,0 +1,49 @@
+import { Field, ObjectType, Int, Float } from "../../src";
+
+@ObjectType({ description: "Object representing cooking recipe" })
+export class Recipe {
+  /*
+    By default, every field gets a complexity of 1.
+    Which can be customized by passing the complexity parameter
+  */
+  @Field({ complexity: 6 })
+  title: string;
+
+  @Field(type => String, { nullable: true, deprecationReason: "Use `description` field instead" })
+  get specification(): string | undefined {
+    return this.description;
+  }
+
+  @Field({ complexity: 5, nullable: true, description: "The recipe" })
+  description?: string;
+
+  @Field(type => [Int])
+  ratings: number[];
+
+  @Field()
+  creationDate: Date;
+
+  @Field(type => Int)
+  ratingsCount: number;
+
+  @Field(type => Float, {
+    nullable: true,
+    /*
+    By default, every field gets a complexity of 1.
+    You can also pass a calculation function in the complexity option
+    to determine a custom complexity.
+    This function will provide the complexity of
+    the child nodes as well as the field input arguments.
+    That way you can make a more realistic estimation of individual field complexity values:
+   */
+    complexity: (args, childComplexity) => childComplexity + 1,
+  })
+  get averageRating(): number | null {
+    const ratingsCount = this.ratings.length;
+    if (ratingsCount === 0) {
+      return null;
+    }
+    const ratingsSum = this.ratings.reduce((a, b) => a + b, 0);
+    return ratingsSum / ratingsCount;
+  }
+}

examples/simple-usage/recipe-type.ts

@@ -2,15 +2,15 @@ import { Field, ObjectType, Int, Float } from "../../src";
 
 @ObjectType({ description: "Object representing cooking recipe" })
 export class Recipe {
-  @Field({ complexity: 5 })
+  @Field()
   title: string;
 
   @Field(type => String, { nullable: true, deprecationReason: "Use `description` field instead" })
   get specification(): string | undefined {
     return this.description;
   }
 
-  @Field({ complexity: 5, nullable: true, description: "The recipe" })
+  @Field({ nullable: true, description: "The recipe description with preparation info" })
   description?: string;
 
   @Field(type => [Int])

src/decorators/types.ts

@@ -1,7 +1,7 @@
 import { GraphQLScalarType } from "graphql";
 import { ValidatorOptions } from "class-validator";
 
-import { ResolverFilterData, ClassType } from "../interfaces";
+import { ResolverFilterData, ClassType, ComplexityResolver } from "../interfaces";
 
 export type TypeValue = ClassType | GraphQLScalarType | Function | object | symbol;
 export type ReturnTypeFuncValue = TypeValue | [TypeValue];
@@ -17,7 +17,7 @@ export type SubscriptionFilterFunc = (
 
 export interface DecoratorTypeOptions {
   nullable?: boolean;
-  complexity?: number;
+  complexity?: number | ComplexityResolver;
 }
 export interface TypeOptions extends DecoratorTypeOptions {
   array?: boolean;

src/interfaces/ComplexityTypes.ts

@@ -0,0 +1,11 @@
+import { GraphQLFieldConfig, GraphQLError } from "graphql";
+
+export type ComplexityResolver = (args: any, complexity: number) => number;
+
+type ComplexityGraphQLFieldConfig<TSource, TContext> = GraphQLFieldConfig<TSource, TContext> & {
+  complexity?: ComplexityResolver | number;
+};
+
+export interface ComplexityGraphQLFieldConfigMap<TSource, TContext> {
+  [key: string]: ComplexityGraphQLFieldConfig<TSource, TContext>;
+}

src/interfaces/index.ts

@@ -5,3 +5,4 @@ export * from "./Publisher";
 export * from "./ResolverData";
 export * from "./ResolverFilterData";
 export * from "./ResolverInterface";
+export * from "./ComplexityTypes";

src/schema/schema-generator.ts

@@ -35,7 +35,7 @@ import {
 } from "../resolvers/create";
 import { BuildContext, BuildContextOptions } from "./build-context";
 import { UnionResolveTypeError, GeneratingSchemaError } from "../errors";
-import { ResolverFilterData } from "../interfaces";
+import { ResolverFilterData, ComplexityGraphQLFieldConfigMap } from "../interfaces";
 import { getFieldMetadataFromInputType, getFieldMetadataFromObjectType } from "./utils";
 
 interface ObjectTypeInfo {
@@ -216,7 +216,7 @@ export abstract class SchemaGenerator {
             return interfaces;
           },
           fields: () => {
-            let fields = objectType.fields!.reduce<GraphQLFieldConfigMap<any, any>>(
+            let fields = objectType.fields!.reduce<ComplexityGraphQLFieldConfigMap<any, any>>(
               (fieldsMap, field) => {
                 const fieldResolverMetadata = getMetadataStorage().fieldResolvers.find(
                   resolver =>
@@ -225,7 +225,7 @@ export abstract class SchemaGenerator {
                     (resolver.resolverClassMetadata === undefined ||
                       resolver.resolverClassMetadata.isAbstract === false),
                 );
-                const fieldConfig: GraphQLFieldConfig<any, any> & { complexity?: number } = {
+                fieldsMap[field.schemaName] = {
                   type: this.getGraphQLOutputType(field.name, field.getType(), field.typeOptions),
                   complexity: field.typeOptions.complexity || 1,
                   args: this.generateHandlerArgs(field.params!),
@@ -235,7 +235,6 @@ export abstract class SchemaGenerator {
                   description: field.description,
                   deprecationReason: field.deprecationReason,
                 };
-                fieldsMap[field.schemaName] = fieldConfig;
                 return fieldsMap;
               },
               {},
@@ -345,7 +344,7 @@ export abstract class SchemaGenerator {
   private static generateHandlerFields<T = any, U = any>(
     handlers: ResolverMetadata[],
   ): GraphQLFieldConfigMap<T, U> {
-    return handlers.reduce<GraphQLFieldConfigMap<T, U>>((fields, handler) => {
+    return handlers.reduce<ComplexityGraphQLFieldConfigMap<T, U>>((fields, handler) => {
       // omit emitting abstract resolver fields
       if (handler.resolverClassMetadata && handler.resolverClassMetadata.isAbstract) {
         return fields;
@@ -360,6 +359,7 @@ export abstract class SchemaGenerator {
         resolve: createHandlerResolver(handler),
         description: handler.description,
         deprecationReason: handler.deprecationReason,
+        complexity: handler.returnTypeOptions.complexity,
       };
       return fields;
     }, {});

tests/functional/fields.ts

@@ -11,6 +11,7 @@ import {
 import { getMetadataStorage } from "../../src/metadata/getMetadataStorage";
 import { getSchemaInfo } from "../helpers/getSchemaInfo";
 import { ObjectType, Field, Query, Resolver } from "../../src";
+import { FieldMetadata } from "../../src/metadata/definitions";
 
 describe("Fields - schema", () => {
   let schemaIntrospection: IntrospectionSchema;
@@ -55,6 +56,9 @@ describe("Fields - schema", () => {
 
       @Field({ name: "overwrittenName", nullable: true })
       overwrittenStringField: string;
+
+      @Field({ name: "complexField", complexity: 10 })
+      complexField: string;
     }
 
     @Resolver(of => SampleObject)
@@ -83,6 +87,15 @@ describe("Fields - schema", () => {
     return (fieldType.type as IntrospectionNonNullTypeRef).ofType! as IntrospectionNamedTypeRef;
   }
 
+  it("should add complexity to the metadata storage", async () => {
+    const metadatStorage = getMetadataStorage();
+    const sampleObj = metadatStorage.objectTypes.find(it => it.name === "SampleObject")!;
+    const complexField = (sampleObj.fields as FieldMetadata[]).find(
+      it => it.name === "complexField",
+    );
+    expect((complexField as FieldMetadata).typeOptions.complexity).toBe(10);
+  });
+
   // tests
   it("should generate schema without errors", async () => {
     expect(schemaIntrospection).toBeDefined();