feat: Add JSON "codegen" output

[kyleconroy]

Inspired by @skabbes here #1470 (comment)

Add a json option to the codegen output. You'll need to use version 2 of the configuration file. You can configure the output path using the out option.

{
  "version": "2",
  "sql": [
    {
      "schema": "postgresql/schema.sql",
      "queries": "postgresql/query.sql",
      "engine": "postgresql",
      "gen": {
        "json": {
          "out": "gen",
          "indent": "  "
        }
      }
    }
  ]
}

sqlc generate --experimental
cat gen/codegen_request.json | gen-go-code
cat gen/codegen_request.json |  gen-ts-code
cat gen/codegen_request.json | wasm-runner ./python-gen.wasm

• Add documentation for the JSON plugin

[skabbes]

This is incredible! It is a testament to the architecture how trivial this was to set up.

At $COMPANY, we rely heavily on code generation for our Typescript and Go base models (~100 tables). Our architecture is basically this pipeline (collectively called "sync schema")

• A Go program (readschema) that:
  • runs information_schema (and pg_*) queries against a dev (or prod!?) database
  • generates a json file
• A Typescript program (writeSchema.ts) that:
  • reads the JSON, and runs them though handlebars templates
  • generates TableName_gen.ts and TableName_gen.go files
  • applies auto-formatting (go fmt, prettier, etc)

This change could completely replace readschema for us, and would allow any improvements there to instead be contributed to directly sqlc. Additionally, the code generators we have would be immediately be useful to others (sqlc -> Typescript) for example (the sqlc Go code generator is already light years ahead of ours though).

Anyway, that's a long winded -hell ya! And I also think this change will inspire someone (maybe me?) to just knock out this 2 year old issue. #296

[kyleconroy]

This change could completely replace readschema for us, and would allow any improvements there to instead be contributed to directly sqlc.

That's great to hear. Once this is merged, I'd love to hear if it's working out for you.

And I also think this change will inspire someone (maybe me?) to just knock out this 2 year old issue. #296

There shouldn't anything blocking you (or anyone else) on implementing codegen for another language. The internal codegen interface is now stable. You can use this PR as a template for adding others.