feat(graphql): added support for auto-exporting the schema (#347)

* Added support for auto-exporting the schema

Supports .json and .graphql formats.
Tests are WIP.

* Made the requested changes

Also fixed the tests by manually defining the mocked method.

* Fixed CI errors, added a change I forgot to commit

* Update postgraphql.ts

* Update postgraphql.ts

* Rename pathgraphqlIntegrationSchemaExport-test.js to postgraphqlIntegrationSchemaExport-test.js

* Rename pathgraphqlIntegrationSchemaExport-test.js.snap to postgraphqlIntegrationSchemaExport-test.js.snap

* Update postgraphql.ts

docs/cli.md

@@ -38,6 +38,8 @@ The usage of the `postgraphql` binary is as follows. To pull up this documentati
     -a, --classic-ids                use classic global id field name. required to support Relay 1
     -j, --dynamic-json               enable dynamic JSON in GraphQL inputs and outputs. uses stringified JSON by default
     -M, --disable-default-mutations  disable default mutations, mutation will only be possible through Postgres functions
+    --export-schema-json [path]      enables exporting the detected schema, in JSON format, to the given location. The directories must exist already, if the file exists it will be overwritten
+    --export-schema-graphql [path]   enables exporting the detected schema, in GraphQL schema format, to the given location. The directories must exist already, if the file exists it will be overwritten
     --show-error-stack [setting]     show JavaScript error stacks in the GraphQL result errors
 
   Get Started:

docs/library.md

@@ -62,6 +62,8 @@ Arguments include:
   - `watchPg`: When true, PostGraphQL will watch your database schemas and re-create the GraphQL API whenever your schema changes, notifying you as it does. This feature requires an event trigger to be added to the database by a superuser. When enabled PostGraphQL will try to add this trigger, if you did not connect as a superuser you will get a warning and the trigger won’t be added.
   - `disableQueryLog`: Turns off GraphQL query logging. By default PostGraphQL will log every GraphQL query it processes along with some other information. Set this to `true` to disable that feature.
   - `enableCors`: Enables some generous CORS settings for the GraphQL endpoint. There are some costs associated when enabling this, if at all possible try to put your API behind a reverse proxy.
+  - `exportJsonSchemaPath`: Enables saving the detected schema, in JSON format, to the given location. The directories must exist already, if the file exists it will be overwritten.
+  - `exportGqlSchemaPath`: Enables saving the detected schema, in GraphQL schema format, to the given location. The directories must exist already, if the file exists it will be overwritten.
 
 [connect]: https://www.npmjs.com/connect
 [express]: https://www.npmjs.com/express

src/postgraphql/__tests__/__mocks__/fs.js

@@ -0,0 +1,11 @@
+const fs = require.requireActual('fs')
+
+// Mock the writeFile for the export tests
+const writeFile = jest.fn((path, contents, callback) => {
+  callback()
+})
+
+module.exports = {
+  ...fs,
+  writeFile,
+}