JSON utilities for selectNoFrom

[jlarmstrongiv]

Discussed in https://discord.com/channels/890118421587578920/1315878442281209907/1315878442281209907

Currently, all the json utilities expect a column. While it is possible to use these utilities via CTEs:

const exampleJson = {
  foo: {
    bar: 42,
  },
};

function toJson<T>(obj: T): RawBuilder<T> {
  return sql`${JSON.stringify(obj)}`;
}

db.with("my_json_table", (db) =>
      db.selectNoFrom((eb) => toJson(exampleJson).as("my_example_json")),
    )
      .selectFrom("my_json_table")
      .select((eb) => eb.ref("my_example_json", "->").key("foo").as("subkey"));


db.with("my_json_table", (db) =>
      db.selectNoFrom((eb) => toJson(exampleJson).as("my_example_json")),
    )
      .selectFrom("my_json_table")
      .select((eb) => eb.jsonPath<"my_example_json">().key("foo").as("subkey"));

It would be better if they had built-in support via:

sql.jsonPath<T extends object>

eb.val({ foo: { bar: 42 } }, '->>').key('foo')

Not only would these functions be helpful for existing projects, they would also be helpful for creating simpler examples for teaching kysely json utilities.