typesafe_supabase_vector.ts

// Inspired by https://github.com/supabase/postgres-meta/issues/578#issuecomment-1955140767

import {
  type GenericSchema,
  type GenericFunction,
} from "@supabase/supabase-js/src/lib/types";
import { type Database } from "types.gen";

type DatabaseShape = {
  [schema_name: string]: GenericSchema;
};

// Helper functions
type ChangeFields<T, R> = Omit<T, keyof R> & R; // Credits: https://stackoverflow.com/a/67884937

type ExtractFnByName<
  DBType extends DatabaseShape,
  FnName extends string,
> = DBType["public"]["Functions"][FnName];

type ChangePgFunctionType<
  DBType extends DatabaseShape,
  FnName extends string,
  FnArg extends string,
> = ChangeFields<
  DBType,
  {
    public: ChangeFields<
      DBType["public"],
      {
        Functions: ChangeFields<
          DBType["public"]["Functions"],
          Record<
            FnName,
            ReplaceVectorArg<FnArg, ExtractFnByName<DBType, FnName>>
          >
        >;
      }
    >;
  }
>;

type ReplaceVectorArg<ArgName extends string, T extends GenericFunction> = Omit<
  T,
  "Args"
> & {
  Args: Omit<T["Args"], ArgName> & Record<ArgName, number[]>;
};

// Fix database types

type TypeSafeDatabase0 = ChangePgFunctionType<
  Database,
  "function1",
  "argname1"
>;

export type TypeSafeDatabase = ChangePgFunctionType<
  TypeSafeDatabase0,
  "function2",
  "argname2"
>;