Support writing configuration as webpack Loader option

From https://github.com/piglovesyou/graphql-let/pull/78#issue-401108869

Ideally it should also be available as a Webpack Loader option.

The problem is the command-line execution, but maybe we can get it from webpack.config.ts. Reasonable spec would be:

• Load config by the following priority:
  1. .graphql-let.yml
     • CWD is where the .graphql-let.yml is located
  2. webpack Loader option
     • If the paths are absolute, it respects as is
     • If the paths are relative, it recognizes config.context as CWD

[piglovesyou]

Hi. True, it should be like the Babel’s configFile option, where babel-loader can pass all babel options OR a relative path to a config file. And yes, accepting a configFilePath option would be our first step.

The problem would be, graphql-let currently expects both .graphql-let.yml and webpackConfig.context are in process.cwd(). So the PR solving is supposed to have tests with changing these paths.

[hasparus]

I encountered two problems while using graphql-let in a Nx monorepo.

1. I have two webpack configs (own for dev and Nx’s for prod) with different context, so I have two copies of .graphql-let.yml. This could be fixed with options.configFile accepting a path to the config.

2. My CI build is failing unless I commit generated files, because on CI they’re generated in <root-dir>/apps/my-app-one/path/to/file.gql (production context) instead of <root-dir>/path/to/file.gql where TypeScript expects them. This could be fixed by options.configFile accepting full config or rootDir and cacheDir options in the loader… right?

Edit: I have something like this. https://github.com/hasparus/graphql-let/tree/loader-options-config-file/test/__fixtures/loader/monorepo