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iTrooz/gen-openapi.ts

Last active October 11, 2025 16:05
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Revisions

  1. iTrooz revised this gist Oct 11, 2025. 1 changed file with 1 addition and 0 deletions.
    1 change: 1 addition & 0 deletions gen-openapi.ts
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    Original file line number Diff line number Diff line change
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    // Help: https://stackoverflow.com/questions/72852736/generating-swagger-json-file-without-running-nest-js-server
    // NestJS 11
    import * as path from 'path';
    import { writeFileSync } from 'fs';
    import { DataType, newDb } from 'pg-mem';
  2. iTrooz created this gist Oct 11, 2025.
    74 changes: 74 additions & 0 deletions gen-openapi.ts
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    @@ -0,0 +1,74 @@
    // Help: https://stackoverflow.com/questions/72852736/generating-swagger-json-file-without-running-nest-js-server
    import * as path from 'path';
    import { writeFileSync } from 'fs';
    import { DataType, newDb } from 'pg-mem';
    import { DataSource } from 'typeorm';
    import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
    import { Test } from '@nestjs/testing';
    import { AppModule } from '../src/app.module';

    async function dumpSwagger() {
    // Setup in-memory Postgres
    const db = newDb();
    db.public.registerFunction({
    name: 'current_database',
    args: [],
    returns: DataType.text,
    implementation: () => 'localdb',
    });
    db.public.registerFunction({
    name: 'version',
    args: [],
    returns: DataType.text,
    implementation: () => '1',
    });

    const datasource = (await db.adapters.createTypeormDataSource({
    type: 'postgres',
    autoLoadEntities: true,
    synchronize: true,
    })) as DataSource;

    await datasource.initialize();
    await datasource.synchronize();

    const moduleFixture = await Test.createTestingModule({
    imports: [AppModule],
    })
    .overrideProvider(DataSource)
    .useValue(datasource)
    .compile();

    let app = moduleFixture.createNestApplication();

    // Create Swagger
    const config = new DocumentBuilder()
    .setTitle('NestJS App')
    .setDescription('NestJS App description')
    .setVersion('1.0')
    .build();

    const document = SwaggerModule.createDocument(app, config);

    await app.close();

    return document;
    }

    dumpSwagger().then(document => {
    const jsonContent = JSON.stringify(document, null, 2);

    const outputFilePath = process.argv[2];
    if (outputFilePath) {
    // Write to specified file
    const resolvedPath = path.resolve(process.cwd(), outputFilePath);
    writeFileSync(resolvedPath, jsonContent, 'utf8');
    console.log(`Swagger JSON dumped to ${resolvedPath}`);
    } else {
    // Dump to stdout
    console.log(jsonContent);
    }
    }).catch(err => {
    console.error(err);
    process.exit(1);
    });