How do you pass arguments to a GraphQL query and validate them using @Args and input types in NestJS?

Q: How do you pass arguments to a GraphQL query and validate them using @Args and input types in NestJS?

// Inline args — simple scalars @Query(() => [User]) users( @Args('page', { type: () => Int, defaultValue: 1 }) page: number, @Args('limit', { type: () => Int, defaultValue: 20 }) limit: number, @Args('search', { nullable: true }) search?: string, ): Promise { return this.usersService.findAll({ page, limit, search }); } // InputType — preferred for complex or reused argument shapes @InputType() export class UsersFilterInput { @Field(() => Int, { defaultValue: 1 }) @IsInt() @Min(1) page: number = 1; @Field(() => Int, { defaultValue: 20 }) @IsInt() @Min(1) @Max(100) limit: number = 20; @Field({ nullable: true }) @IsOptional() @IsString() search?: string; } @Query(() => [User]) users(@Args('filter') filter: UsersFilterInput): Promise { return this.usersService.findAll(filter); } // Enable validation globally app.useGlobalPipes(new ValidationPipe()); type: () => Int is required for Int and Float — TypeScript metadata only knows 'Number'. nullable: true makes the argument optional in the schema. defaultValue in @Args or @Field sets the GraphQL default in the schema. @InputType() classes are validated by ValidationPipe using class-validator decorators. Use InputType for 3+ arguments or reused argument shapes — it keeps resolvers clean.

Difficulty: 5/10

@Args decorator, Input DTO validation, NestJS GraphQL integration

Use @Args('name', options) for inline scalar arguments or declare an @InputType() class and use @Args('input') for complex arguments. Input types are validated by the global ValidationPipe using class-validator decorators. The type option in @Args is required for non-string scalars because TypeScript metadata cannot infer GraphQL scalar types.

Inline args and InputType for query arguments

Argument declaration rules:

1
type: () => Int is required for Int and Float — TypeScript metadata only knows 'Number'.
2

How do you pass arguments to a GraphQL query and validate them using @Args and input types in NestJS?

Difficulty: 5/10

@Args decorator, Input DTO validation, NestJS GraphQL integration

Use @Args('name', options) for inline scalar arguments or declare an @InputType() class and use @Args('input') for complex arguments. Input types are validated by the global ValidationPipe using class-validator decorators. The type option in @Args is required for non-string scalars because TypeScript metadata cannot infer GraphQL scalar types.

Inline args and InputType for query arguments

Argument declaration rules:

1
type: () => Int is required for Int and Float — TypeScript metadata only knows 'Number'.
2

How do you pass arguments to a GraphQL query and validate them using @Args and input types in NestJS?

How do you pass arguments to a GraphQL query and validate them using @Args and input types in NestJS?

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