cli: add native-query create subcommand to create native query configuration

[hallettj]

This is work in progress. The new subcommand is hidden by a build-time feature flag, native-query-subcommand, so that the work that is done so far can be reviewed and merged.

The new command accepts a name for a native query, an optional input collection, and a file containing an aggregation pipeline, and produces a native query configuration file that includes type declarations inferred from the pipeline.

Here is an example that uses the sample-mflix connector configuration in the repo. Create a file called pipeline.json containing this pipeline:

[
  {
    "$replaceWith": {
      "title_words": { "$split": ["$title", " "] }
    }
  },
  { "$unwind": { "path": "$title_words" } },
  {
    "$group": {
      "_id": "$title_words",
      "count": { "$count": {} }
    }
  }
]

Then run this command:

$ cargo run -p mongodb-cli-plugin --features native-query-subcommand -- -\
  -p fixtures/hasura/sample_mflix/connector/ \
  native-query create pipeline.json --name title_words --collection movies

That should create fixtures/hasura/sample_mflix/connector/native_queries/title_words.json

There are notes on what is and isn't done in https://linear.app/hasura/project/mongodb-automatic-native-queries-fceb7aed3196/overview. Here is a copy of those notes:

These CLI commands will let users create native queries without having to write type declarations themselves. The CLI infers the parameter list, and return document type. We will want a type annotation syntax for arguments, but it may be possible to infer parameter types in some cases.

Here is what's done:

• CLI command to generate native query configuration without support for parameters, supports a subset of aggregation pipeline features
• supported pipeline stages:
  • $documents
  • $match
  • $sort
  • $limit
  • $skip
  • $group
  • $replaceWith
  • $unwind
• string syntax for references to input document fields is supported, e.g. "$tomatoes.viewer.rating"
• supported aggregation operators:
  • $split

[codedmart]

👍

[codedmart]

Curious why the other number types are still todo! other then Double? Aren't the other number types pretty easy to add here?

[hallettj]

Yes, it very easy to add implementations for the other scalar types. It just hasn't made it to the top of my todo list.