Generate

Generate a protobuf definition for a gRPC service from a GraphQL schema

wgc grpc-service generate

The generate command generates a protobuf definition and mapping file for a gRPC service from a GraphQL schema, which can be used to implement a gRPC service and can be used for the composition.

It supports two modes:

1. Schema Mode: Generates a protobuf definition that mirrors the GraphQL schema. Used for implementing Subgraphs in gRPC (Connect Backend).
2. Operations Mode: Generates a protobuf definition based on a set of GraphQL operations. Used for generating client SDKs (Connect Client).

Usage

wgc grpc-service generate [options] [service-name]

Arguments

Argument	Description	Default
service-name	Name of the gRPC service	service.v1

Options

Option	Description	Default
-i, --input <path-to-input>	The GraphQL schema file to generate a protobuf schema from	Required
-o, --output <path-to-output>	The output directory for the protobuf schema	.
-p, --package-name <name>	The name of the proto package	service.v1
-g, --go-package <name>	Adds an option go_package to the proto file	None
-w, --with-operations <path>	Path to directory containing GraphQL operation files. Enables Operations Mode.	None
-l, --proto-lock <path>	Path to existing proto lock file.	<outdir>/service.proto.lock.json
--custom-scalar-mapping <json>	Custom scalar type mappings as JSON string. Example: {"DateTime":"google.protobuf.Timestamp"}	None
--custom-scalar-mapping-file <path>	Path to JSON file containing custom scalar type mappings.	None
--max-depth <number>	Maximum recursion depth for processing nested selections.	50

Description

This command generates a protobuf definition for a gRPC service from a GraphQL schema.

Examples

Generate a protobuf definition for a gRPC service from a GraphQL schema (Schema Mode)

wgc grpc-service generate -i ./schema.graphql -o ./service MyService

Generate a protobuf definition from operations (Operations Mode)

wgc grpc-service generate \
  -i ./schema.graphql \
  -o ./gen \
  --with-operations ./operations \
  --package-name my.service.v1 \
  MyService

Define a custom package name

wgc grpc-service generate -i ./schema.graphql -o ./service MyService --package-name my.custom.package

Define a custom go package name

wgc grpc-service generate -i ./schema.graphql -o ./service MyService --go-package github.com/wundergraph/cosmo/service/my-service

Output

The command generates multiple files in the output directory:

• service.proto: The protobuf definition for the gRPC service
• service.mapping.json: The mapping file for the gRPC service (Schema Mode only)
• service.proto.lock.json: The lock file for the protobuf definition

The generated protobuf definition can be used to implement a gRPC service in any language that supports protobuf, or to generate client SDKs.

The mapping and the protobuf definition is needed for the composition part.

See also: gRPC Services · GraphQL Support for gRPC Integration