graphQl in nest

src/
├── common/
│   ├── enums.ts
│   ├── scalars.ts
│   ├── directives.ts
│   ├── interfaces.ts
│   ├── shared.models.ts
│
├── resolvers/
│   ├── user.resolver.ts
│   ├── post.resolver.ts
│   ├── comment.resolver.ts
│   ├── subscription.resolver.ts
│   ├── union.resolver.ts
│   ├── enum.resolver.ts
│   ├── interface.resolver.ts
│   ├── federation.resolver.ts
│
├── mutations/
│   ├── user.mutation.ts
│   ├── post.mutation.ts
│   ├── comment.mutation.ts
│   ├── federation.mutation.ts
│
├── subscriptions/
│   ├── comment.sub.ts
│   ├── subscription.events.ts
│
├── scalars/
│   ├── custom-scalar.resolver.ts
│   ├── custom-scalar.scalar.ts
│
├── directives/
│   ├── custom.directive.ts
│   ├── custom.directive.ts
│
├── interfaces/
│   ├── custom.interface.ts
│   ├── custom.interface.resolver.ts
│
├── unions/
│   ├── custom.union.ts
│   ├── custom.union.resolver.ts
│
├── enums/
│   ├── custom.enum.ts
│   ├── custom.enum.resolver.ts
│
├── field-middleware/
│   ├── custom-field-middleware.middleware.ts
│
├── mapped-types/
│   ├── mapped.types.ts
│
├── plugins/
│   ├── custom.plugin.ts
│
├── complexity/
│   ├── custom-complexity.ts
│
├── extensions/
│   ├── custom.extension.ts
│
├── cli-plugin/
│   ├── custom.cli.plugin.ts
│
├── generating-sdl/
│   ├── custom.sdl.ts
│
├── sharing-models/
│   ├── shared.model.ts
│   ├── shared.model.resolver.ts
│
├── other-features/
│   ├── feature1/
│   │   ├── feature1.resolver.ts
│   ├── feature2/
│   │   ├── feature2.resolver.ts
│
├── federation/
│   ├── federated.resolver.ts
│   ├── federated.service.ts
│
├── migration/
│   ├── migration-guide.md
│
├── app.module.ts
├── main.ts

// src/common/enums.ts
import { registerEnumType } from '@nestjs/graphql';

export enum UserRole {
  USER = 'USER',
  ADMIN = 'ADMIN',
}

registerEnumType(UserRole, {
  name: 'UserRole',
  description: 'User roles in the application',
});

// Define other enums as needed

// src/common/scalars.ts
import { Scalar } from '@nestjs/graphql';

@Scalar('Date', () => Date)
export class DateScalar {}

// Define other custom scalars as needed

// src/common/directives.ts
import { Directive, FieldDefinitionNode, GraphQLDirective, GraphQLObjectType } from 'graphql';
import { SchemaDirectiveVisitor } from 'graphql-tools';

@Directive('@custom')
export class CustomDirective extends SchemaDirectiveVisitor {
  visitFieldDefinition(field: FieldDefinitionNode, details: { objectType: GraphQLObjectType }) {
    const { resolve } = this.config;
    const originalResolve = field.resolve || details.objectType.getFields()[field.name].resolve;

    field.resolve = async (source, args, context, info) => {
      // Implement custom logic here before or after the original resolver
      const result = await originalResolve.call(this, source, args, context, info);
      // Implement custom logic here after the original resolver
      return result;
    };
  }
}

// Define other custom directives as needed

// src/common/interfaces.ts
import { InterfaceType, Field, ID } from '@nestjs/graphql';

@InterfaceType()
export abstract class CustomInterface {
  @Field(() => ID)
  id: string;

  @Field()
  name: string;
}

// Define other custom interfaces as needed

// src/common/shared.models.ts
import { ObjectType, Field, ID } from '@nestjs/graphql';

@ObjectType()
export class SharedModel {
  @Field(() => ID)
  id: string;

  @Field()
  name: string;
}

// Define other shared models as needed

// src/resolvers/user.resolver.ts
import { Resolver, Query, Mutation, Args } from '@nestjs/graphql';
import { UserService } from '../services/user.service';
import { User } from '../models/user.model';

@Resolver(() => User)
export class UserResolver {
  constructor(private readonly userService: UserService) {}

  @Query(() => User)
  async getUser(@Args('id') id: string): Promise<User> {
    // Implement logic to retrieve a user by ID using userService
    return this.userService.findById(id);
  }

  @Mutation(() => User)
  async createUser(@Args('input') input: CreateUserInput): Promise<User> {
    // Implement logic to create a new user using userService
    return this.userService.createUser(input);
  }

  // Define other queries and mutations related to users
}

// src/resolvers/post.resolver.ts
import { Resolver, Query, Mutation, Args } from '@nestjs/graphql';
import { PostService } from '../services/post.service';
import { Post } from '../models/post.model';

@Resolver(() => Post)
export class PostResolver {
  constructor(private readonly postService: PostService) {}

  @Query(() => Post)
  async getPost(@Args('id') id: string): Promise<Post> {
    // Implement logic to retrieve a post by ID using postService
    return this.postService.findById(id);
  }

  @Mutation(() => Post)
  async createPost(@Args('input') input: CreatePostInput): Promise<Post> {
    // Implement logic to create a new post using postService
    return this.postService.createPost(input);
  }

  // Define other queries and mutations related to posts
}

// src/resolvers/comment.resolver.ts
import { Resolver, Query, Mutation, Args } from '@nestjs/graphql';
import { CommentService } from '../services/comment.service';
import { Comment } from '../models/comment.model';

@Resolver(() => Comment)
export class CommentResolver {
  constructor(private readonly commentService: CommentService) {}

  @Query(() => Comment)
  async getComment(@Args('id') id: string): Promise<Comment> {
    // Implement logic to retrieve a comment by ID using commentService
    return this.commentService.findById(id);
  }

  @Mutation(() => Comment)
  async createComment(@Args('input') input: CreateCommentInput): Promise<Comment> {
    // Implement logic to create a new comment using commentService
    return this.commentService.createComment(input);
  }

  // Define other queries and mutations related to comments
}

// src/resolvers/subscription.resolver.ts
import { Resolver, Subscription } from '@nestjs/graphql';

@Resolver()
export class SubscriptionResolver {
  @Subscription(() => String, {
    resolve: (payload) => payload,
    filter: (payload, variables) => {
      // Implement logic to filter subscriptions based on variables
      return true;
    },
  })
  async newNotification() {
    // Implement logic to publish subscription data
    return 'New notification!';
  }
}

// src/resolvers/union.resolver.ts
import { Resolver, ResolveType } from '@nestjs/graphql';
import { UnionType } from '../models/union.model';
import { User } from '../models/user.model';
import { Post } from '../models/post.model';

@Resolver(UnionType)
export class UnionResolver {
  @ResolveType(() => User)
  resolveTypeUser() {
    return User;
  }

  @ResolveType(() => Post)
  resolveTypePost() {
    return Post;
  }

  // Define resolveType methods for other types included in the union
}

// src/resolvers/enum.resolver.ts
import { Resolver } from '@nestjs/graphql';
import { EnumType } from '../models/enum.model';

@Resolver(EnumType)
export class EnumResolver {
  // Implement custom resolvers or queries related to EnumType
}

// src/resolvers/interface.resolver.ts
import { Resolver, ResolveField, Parent } from '@nestjs/graphql';
import { CustomInterface } from '../models/interface.model';
import { UserService } from '../services/user.service';

@Resolver(CustomInterface)
export class InterfaceResolver {
  constructor(private userService: UserService) {}

  @ResolveField()
  async user(@Parent() customInterface: CustomInterface) {
    // Implement custom logic to resolve the 'user' field of the interface
    return this.userService.getUserById(customInterface.userId);
  }
}

// src/resolvers/federation.resolver.ts

// src/mutations/user.mutation.ts
import { Resolver, Mutation, Args } from '@nestjs/graphql';
import { UserService } from '../services/user.service';
import { CreateUserInput } from '../dto/create-user.input';
import { User } from '../models/user.model';

@Resolver()
export class UserMutationResolver {
  constructor(private readonly userService: UserService) {}

  @Mutation(() => User)
  async createUser(@Args('input') input: CreateUserInput): Promise<User> {
    // Implement logic to create a new user using userService
    return this.userService.createUser(input);
  }

  // Define other mutations related to users
}

// src/mutations/post.mutation.ts
import { Resolver, Mutation, Args } from '@nestjs/graphql';
import { PostService } from '../services/post.service';
import { CreatePostInput } from '../dto/create-post.input';
import { Post } from '../models/post.model';

@Resolver()
export class PostMutationResolver {
  constructor(private readonly postService: PostService) {}

  @Mutation(() => Post)
  async createPost(@Args('input') input: CreatePostInput): Promise<Post> {
    // Implement logic to create a new post using postService
    return this.postService.createPost(input);
  }

  // Define other mutations related to posts
}

// src/mutations/comment.mutation.ts
import { Resolver, Mutation, Args } from '@nestjs/graphql';
import { CommentService } from '../services/comment.service';
import { CreateCommentInput } from '../dto/create-comment.input';
import { Comment } from '../models/comment.model';

@Resolver()
export class CommentMutationResolver {
  constructor(private readonly commentService: CommentService) {}

  @Mutation(() => Comment)
  async createComment(@Args('input') input: CreateCommentInput): Promise<Comment> {
    // Implement logic to create a new comment using commentService
    return this.commentService.createComment(input);
  }

  // Define other mutations related to comments
}

// src/mutations/federation.mutation.ts
import { Resolver, Mutation, Args } from '@nestjs/graphql';
import { FederatedService } from '../services/federated.service';
import { CreateFederatedInput } from '../dto/create-federated.input';
import { FederatedType } from '../models/federated.model';

@Resolver()
export class FederationMutationResolver {
  constructor(private readonly federatedService: FederatedService) {}

  @Mutation(() => FederatedType)
  async createFederated(
    @Args('input') input: CreateFederatedInput,
  ): Promise<FederatedType> {
    // Implement logic to create a new federated type using federatedService
    return this.federatedService.createFederated(input);
  }

  // Define other mutations related to federated types if needed
}

// src/subscriptions/comment.sub.ts
import { Resolver, Subscription } from '@nestjs/graphql';

@Resolver()
export class CommentSubscriptionResolver {
  @Subscription(() => String, {
    resolve: (payload) => payload,
    filter: (payload, variables) => {
      // Implement logic to filter subscriptions based on variables
      return true;
    },
  })
  async newComment() {
    // Implement logic to publish subscription data for new comments
    return 'New comment!';
  }
}

// src/subscriptions/subscription.events.ts
import { PubSub } from 'graphql-subscriptions';

export const pubSub = new PubSub();

// src/scalars/custom-scalar.resolver.ts
import { Resolver, Query } from '@nestjs/graphql';

@Resolver('Date')
export class CustomScalarResolver {
  @Query(() => Date)
  async currentDate(): Promise<Date> {
    return new Date();
  }

  // Define other queries or resolvers related to the custom scalar
}

// src/scalars/custom-scalar.scalar.ts
import { Scalar } from '@nestjs/graphql';

@Scalar('Date')
export class CustomScalar {
  description = 'Custom scalar type for representing dates';

  parseValue(value: string) {
    return new Date(value);
  }

  serialize(value: Date) {
    return value.toISOString();
  }

  parseLiteral(ast) {
    if (ast.kind === 'StringValue') {
      return new Date(ast.value);
    }
    return null;
  }
}

// src/directives/custom.directive.ts
import { SchemaDirectiveVisitor } from 'graphql-tools';
import { defaultFieldResolver } from 'graphql';

export class CustomDirective extends SchemaDirectiveVisitor {
  visitFieldDefinition(field) {
    const { resolve = defaultFieldResolver } = field;
    field.resolve = async function (...args) {
      const result = await resolve.apply(this, args);
      // Implement custom directive logic here, for example, modify the result
      return result;
    };
  }
}

// src/directives/custom.directive.ts
import { SchemaDirectiveVisitor } from 'graphql-tools';
import { defaultFieldResolver } from 'graphql';

export class AnotherCustomDirective extends SchemaDirectiveVisitor {
  visitFieldDefinition(field) {
    const { resolve = defaultFieldResolver } = field;
    field.resolve = async function (...args) {
      const result = await resolve.apply(this, args);
      // Implement custom directive logic here, for example, modify the result
      return result;
    };
  }
}

// src/interfaces/custom.interface.ts
import { InterfaceType, Field, ID } from '@nestjs/graphql';

@InterfaceType()
export abstract class CustomInterface {
  @Field(() => ID)
  id: string;

  @Field()
  name: string;

  // Define other fields and methods for the interface
}

// src/interfaces/custom.interface.resolver.ts
import { Resolver, ResolveField, Parent } from '@nestjs/graphql';
import { CustomInterface } from './custom.interface';
import { UserService } from '../services/user.service';

@Resolver(() => CustomInterface)
export class CustomInterfaceResolver {
  constructor(private userService: UserService) {}

  @ResolveField()
  async user(@Parent() customInterface: CustomInterface) {
    // Implement custom logic to resolve the 'user' field of the interface
    return this.userService.getUserById(customInterface.userId);
  }

  // Define other resolver methods for the interface
}

// src/unions/custom.union.ts
import { UnionType, ObjectType, Field } from '@nestjs/graphql';
import { User } from '../models/user.model';
import { Post } from '../models/post.model';

@ObjectType()
export class UserType {
  @Field()
  username: string;

  // Define other fields specific to the User type
}

@ObjectType()
export class PostType {
  @Field()
  title: string;

  // Define other fields specific to the Post type
}

@UnionType([UserType, PostType])
export class CustomUnion {
  @Field()
  __typename: 'UserType' | 'PostType';
}

// src/unions/custom.union.resolver.ts
import { Resolver, ResolveType } from '@nestjs/graphql';
import { CustomUnion } from './custom.union';
import { UserType, PostType } from './custom.union';

@Resolver(() => CustomUnion)
export class CustomUnionResolver {
  @ResolveType(() => UserType)
  resolveUserType() {
    return UserType;
  }

  @ResolveType(() => PostType)
  resolvePostType() {
    return PostType;
  }

  // Define resolveType methods for other types included in the union
}

// src/enums/custom.enum.ts
import { registerEnumType } from '@nestjs/graphql';

export enum CustomEnum {
  VALUE1 = 'VALUE1',
  VALUE2 = 'VALUE2',
  VALUE3 = 'VALUE3',
}

registerEnumType(CustomEnum, {
  name: 'CustomEnum',
  description: 'Custom enum type for representing choices',
});

// src/enums/custom.enum.resolver.ts
import { Resolver } from '@nestjs/graphql';
import { CustomEnum } from './custom.enum';

@Resolver(() => CustomEnum)
export class CustomEnumResolver {
  // Implement custom resolvers or queries related to CustomEnum
}

// src/field-middleware/custom-field-middleware.middleware.ts
import { MiddlewareFn } from '@nestjs/graphql';

export const CustomFieldMiddleware: MiddlewareFn = async (resolverData, next) => {
  // Implement custom field middleware logic here
  const result = await next();
  // Implement additional logic after the resolver execution
  return result;
};

// src/mapped-types/mapped.types.ts
import { InputType, PartialType } from '@nestjs/graphql';
import { CreateUserInput } from '../dto/create-user.input';

@InputType()
export class UpdateUserInput extends PartialType(CreateUserInput) {
  // Define additional fields or modifications to the mapped type
}

// src/plugins/custom.plugin.ts
import { Plugin } from '@nestjs/graphql';

@Plugin()
export class CustomPlugin {
  // Implement custom plugin logic here
}

// src/complexity/custom-complexity.ts
import { ComplexityEstimator, QueryComplexityEstimator } from '@nestjs/graphql';

export const customComplexity: ComplexityEstimator = (options) => {
  // Implement custom complexity analysis logic here based on resolver options
  return 1; // Return the computed complexity value
};

export const queryComplexity: QueryComplexityEstimator = (options, childComplexity) => {
  // Implement custom query complexity analysis logic here based on resolver options and child complexity
  return 1; // Return the computed query complexity value
};

// src/extensions/custom.extension.ts
import { Plugin } from '@nestjs/graphql';

@Plugin()
export class CustomExtension {
  // Implement custom extension logic here
}

// src/cli-plugin/custom.cli.plugin.ts
import { Plugin } from '@nestjs/cli';

@Plugin()
export class CustomCliPlugin {
  // Implement custom CLI plugin logic here
}

// src/generating-sdl/custom.sdl.ts
import { SchemaGenerator } from '@nestjs/graphql';

export class CustomSchemaGenerator extends SchemaGenerator {
  // Implement custom SDL generation logic here
}

// src/sharing-models/shared.model.ts
import { ObjectType, Field, ID } from '@nestjs/graphql';

@ObjectType()
export class SharedModel {
  @Field(() => ID)
  id: string;

  @Field()
  name: string;

  // Define other fields specific to the shared model
}

// src/sharing-models/shared.model.resolver.ts
import { Resolver, Query } from '@nestjs/graphql';
import { SharedModel } from './shared.model';

@Resolver(() => SharedModel)
export class SharedModelResolver {
  @Query(() => SharedModel)
  async getSharedModel(): Promise<SharedModel> {
    // Implement logic to retrieve or generate a shared model
    return {
      id: '1',
      name: 'Shared Item',
    };
  }

  // Define other queries or resolvers related to the shared model
}

// src/other-features/feature1/feature1.resolver.ts
import { Resolver, Query } from '@nestjs/graphql';

@Resolver()
export class Feature1Resolver {
  @Query(() => String)
  async feature1Query(): Promise<string> {
    // Implement logic specific to Feature 1
    return 'Result from Feature 1';
  }

  // Define other queries or resolvers related to Feature 1
}

// src/other-features/feature2/feature2.resolver.ts
import { Resolver, Query } from '@nestjs/graphql';

@Resolver()
export class Feature2Resolver {
  @Query(() => String)
  async feature2Query(): Promise<string> {
    // Implement logic specific to Feature 2
    return 'Result from Feature 2';
  }

  // Define other queries or resolvers related to Feature 2
}


## federation

```js
// src/federation/federated.resolver.ts
import { Resolver, Query } from '@nestjs/graphql';

@Resolver()
export class FederatedResolver {
  @Query(() => String)
  async federatedQuery(): Promise<string> {
    // Implement logic specific to federated types
    return 'Result from Federated Resolver';
  }

  // Define other queries or resolvers related to federated types
}

// src/federation/federated.service.ts
import { Injectable } from '@nestjs/common';

@Injectable()
export class FederatedService {
  // Implement logic related to federated types
}

# migration-guide.md

# Migration Guide

This document provides a guide for migrating from the previous version of the GraphQL API to the current version.

## Table of Contents

1. Introduction
2. Changes in the Current Version
   - List of breaking changes or significant updates
3. Migration Steps
   - Detailed steps and instructions for migrating
4. Conclusion
   - Final notes and recommendations

...

[Insert detailed content for your migration guide here]

//app.module.ts
import { Module } from '@nestjs/common';
import { GraphQLModule } from '@nestjs/graphql';
import { UserModule } from './user/user.module'; // Import your modules as needed
import { PostModule } from './post/post.module';
import { CommentModule } from './comment/comment.module';
import { SubscriptionModule } from './subscription/subscription.module';
import { ScalarsModule } from './scalars/scalars.module';
import { DirectivesModule } from './directives/directives.module';
import { InterfacesModule } from './interfaces/interfaces.module';
import { UnionsModule } from './unions/unions.module';
import { EnumsModule } from './enums/enums.module';
import { FieldMiddlewareModule } from './field-middleware/field-middleware.module';
import { MappedTypesModule } from './mapped-types/mapped-types.module';
import { PluginsModule } from './plugins/plugins.module';
import { ComplexityModule } from './complexity/complexity.module';
import { ExtensionsModule } from './extensions/extensions.module';
import { CliPluginModule } from './cli-plugin/cli-plugin.module';
import { GeneratingSdlModule } from './generating-sdl/generating-sdl.module';
import { SharingModelsModule } from './sharing-models/sharing-models.module';
import { OtherFeaturesModule } from './other-features/other-features.module';
import { FederationModule } from './federation/federation.module';

@Module({
  imports: [
    GraphQLModule.forRoot({
      autoSchemaFile: 'schema.gql', // Provide a schema file
    }),
    UserModule,
    PostModule,
    CommentModule,
    SubscriptionModule,
    ScalarsModule,
    DirectivesModule,
    InterfacesModule,
    UnionsModule,
    EnumsModule,
    FieldMiddlewareModule,
    MappedTypesModule,
    PluginsModule,
    ComplexityModule,
    ExtensionsModule,
    CliPluginModule,
    GeneratingSdlModule,
    SharingModelsModule,
    OtherFeaturesModule,
    FederationModule,
  ],
})
export class AppModule {}

//main.ts
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  await app.listen(3000); // Set your desired port number here
}

bootstrap();