132 lines
6.5 KiB
Markdown
132 lines
6.5 KiB
Markdown
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# gRPC Protobuf Loader
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A utility package for loading `.proto` files for use with gRPC, using the latest Protobuf.js package.
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Please refer to [protobuf.js' documentation](https://github.com/dcodeIO/protobuf.js/blob/master/README.md)
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to understands its features and limitations.
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## Installation
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```sh
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npm install @grpc/proto-loader
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```
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## Usage
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```js
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const protoLoader = require('@grpc/proto-loader');
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const grpcLibrary = require('grpc');
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// OR
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const grpcLibrary = require('@grpc/grpc-js');
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protoLoader.load(protoFileName, options).then(packageDefinition => {
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const packageObject = grpcLibrary.loadPackageDefinition(packageDefinition);
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});
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// OR
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const packageDefinition = protoLoader.loadSync(protoFileName, options);
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const packageObject = grpcLibrary.loadPackageDefinition(packageDefinition);
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```
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The options parameter is an object that can have the following optional properties:
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| Field name | Valid values | Description
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|------------|--------------|------------
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| `keepCase` | `true` or `false` | Preserve field names. The default is to change them to camel case.
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| `longs` | `String` or `Number` | The type to use to represent `long` values. Defaults to a `Long` object type.
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| `enums` | `String` | The type to use to represent `enum` values. Defaults to the numeric value.
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| `bytes` | `Array` or `String` | The type to use to represent `bytes` values. Defaults to `Buffer`.
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| `defaults` | `true` or `false` | Set default values on output objects. Defaults to `false`.
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| `arrays` | `true` or `false` | Set empty arrays for missing array values even if `defaults` is `false` Defaults to `false`.
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| `objects` | `true` or `false` | Set empty objects for missing object values even if `defaults` is `false` Defaults to `false`.
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| `oneofs` | `true` or `false` | Set virtual oneof properties to the present field's name. Defaults to `false`.
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| `json` | `true` or `false` | Represent `Infinity` and `NaN` as strings in `float` fields, and automatically decode `google.protobuf.Any` values. Defaults to `false`
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| `includeDirs` | An array of strings | A list of search paths for imported `.proto` files.
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The following options object closely approximates the existing behavior of `grpc.load`:
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```js
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const options = {
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keepCase: true,
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longs: String,
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enums: String,
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defaults: true,
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oneofs: true
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}
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```
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## Generating TypeScript types
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The `proto-loader-gen-types` script distributed with this package can be used to generate TypeScript type information for the objects loaded at runtime. More information about how to use it can be found in [the *@grpc/proto-loader TypeScript Type Generator CLI Tool* proposal document](https://github.com/grpc/proposal/blob/master/L70-node-proto-loader-type-generator.md). The arguments mostly match the `load` function's options; the full usage information is as follows:
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```console
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proto-loader-gen-types.js [options] filenames...
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Options:
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--help Show help [boolean]
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--version Show version number [boolean]
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--keepCase Preserve the case of field names
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[boolean] [default: false]
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--longs The type that should be used to output 64 bit integer
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values. Can be String, Number[string] [default: "Long"]
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--enums The type that should be used to output enum fields. Can
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be String [string] [default: "number"]
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--bytes The type that should be used to output bytes fields.
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Can be String, Array [string] [default: "Buffer"]
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--defaults Output default values for omitted fields
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[boolean] [default: false]
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--arrays Output default values for omitted repeated fields even
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if --defaults is not set [boolean] [default: false]
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--objects Output default values for omitted message fields even
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if --defaults is not set [boolean] [default: false]
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--oneofs Output virtual oneof fields set to the present field's
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name [boolean] [default: false]
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--json Represent Infinity and NaN as strings in float fields.
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Also decode google.protobuf.Any automatically
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[boolean] [default: false]
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--includeComments Generate doc comments from comments in the original
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files [boolean] [default: false]
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-I, --includeDirs Directories to search for included files [array]
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-O, --outDir Directory in which to output files [string] [required]
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--grpcLib The gRPC implementation library that these types will
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be used with. If not provided, some types will not be
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generated [string]
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--inputTemplate Template for mapping input or "permissive" type names
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[string] [default: "%s"]
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--outputTemplate Template for mapping output or "restricted" type names
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[string] [default: "%s__Output"]
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--inputBranded Output property for branded type for "permissive"
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types with fullName of the Message as its value
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[boolean] [default: false]
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--outputBranded Output property for branded type for "restricted"
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types with fullName of the Message as its value
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[boolean] [default: false]
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```
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### Example Usage
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Generate the types:
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```sh
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$(npm bin)/proto-loader-gen-types --longs=String --enums=String --defaults --oneofs --grpcLib=@grpc/grpc-js --outDir=proto/ proto/*.proto
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```
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Consume the types:
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```ts
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import * as grpc from '@grpc/grpc-js';
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import * as protoLoader from '@grpc/proto-loader';
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import { ProtoGrpcType } from './proto/example';
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import { ExampleHandlers } from './proto/example_package/Example';
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const exampleServer: ExampleHandlers = {
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// server handlers implementation...
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};
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const packageDefinition = protoLoader.loadSync('./proto/example.proto');
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const proto = (grpc.loadPackageDefinition(
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packageDefinition
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) as unknown) as ProtoGrpcType;
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const server = new grpc.Server();
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server.addService(proto.example_package.Example.service, exampleServer);
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```
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