> ## Documentation Index
> Fetch the complete documentation index at: https://wundergraphinc-ahmet-eng-8587-documentation-for-connect-cli.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# 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

```bash theme={"system"}
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)

```bash theme={"system"}
wgc grpc-service generate -i ./schema.graphql -o ./service MyService
```

### Generate a protobuf definition from operations (Operations Mode)

```bash theme={"system"}
wgc grpc-service generate \
  -i ./schema.graphql \
  -o ./gen \
  --with-operations ./operations \
  --package-name my.service.v1 \
  MyService
```

### Define a custom package name

```bash theme={"system"}
wgc grpc-service generate -i ./schema.graphql -o ./service MyService --package-name my.custom.package
```

### Define a custom go package name

```bash theme={"system"}
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](../router/gRPC/grpc-services) · [GraphQL Support for gRPC Integration](../router/gRPC/graphql-support)