DT
Drizzle Team•7mo ago
icomad

Table factory typescript problem

I have a basic table schema that all tables share (id, timestamps and more) and I'm trying to write an helper function that returns a pgTable with these fields already added. Right now it looks like this: 
const baseTable: PgTableFn = (tableName, fields, extraConfig) => 
  pgTable(
    tableName, 
    {
      id: uuid("id").primaryKey(), 
      ...fields, 
      createdAt: timestamp("created_at"), 
      updatedAt: timestamp("updated_at")
    }, 
    extraConfig
  );

const testTable = baseTable(
  "test_table", 
  { test: text("test") }, 
  table => ({
    testIdx: index().on(table.test), // <- This is ok
    errIdx: index().on(table.createdAt) // <- This gives me an error
  })
);
const baseTable: PgTableFn = (tableName, fields, extraConfig) => 
  pgTable(
    tableName, 
    {
      id: uuid("id").primaryKey(), 
      ...fields, 
      createdAt: timestamp("created_at"), 
      updatedAt: timestamp("updated_at")
    }, 
    extraConfig
  );

const testTable = baseTable(
  "test_table", 
  { test: text("test") }, 
  table => ({
    testIdx: index().on(table.test), // <- This is ok
    errIdx: index().on(table.createdAt) // <- This gives me an error
  })
);
This is wrong though because testTable is not typed correctly and it is missing all the shared fields. How would I go about correcting this?
2 Replies
A Dapper Raccoon
A Dapper Raccoon•7mo ago
I'm not great with typescript and I really hope someone else might provide a better solution, but I couldn't see any obvious way to shim the extra columns into TColumnsMap while using the *TableFn interface for the wrapper, since it's explicitly inferred from the fields parameter. I ended up typing my function similar to: 
const baseColumns = { /* ... */ };

const baseTable = <
  TTableName extends string,
  TColumnsMap extends Record<string, SQLiteColumnBuilderBase>
>(
  name: TTableName,
  fields: TColumnsMap,
  extraConfig?: (self: BuildColumns<TTableName, TColumnsMap & typeof baseColumns, 'sqlite'>) => SQLiteTableExtraConfig
) => {
  const {id, ...baseColumnsRest} = baseColumns;

  return sqliteTable(
    name,
    {
      id,
      ...fields,
      ...baseColumnsRest,
    },
    extraConfig
  );
}
const baseColumns = { /* ... */ };

const baseTable = <
  TTableName extends string,
  TColumnsMap extends Record<string, SQLiteColumnBuilderBase>
>(
  name: TTableName,
  fields: TColumnsMap,
  extraConfig?: (self: BuildColumns<TTableName, TColumnsMap & typeof baseColumns, 'sqlite'>) => SQLiteTableExtraConfig
) => {
  const {id, ...baseColumnsRest} = baseColumns;

  return sqliteTable(
    name,
    {
      id,
      ...fields,
      ...baseColumnsRest,
    },
    extraConfig
  );
}
I did try my hand at a generic interface to serve as a type for various "table factory functions" using whatever default columns - and it did work - but it uses a lot of copy & paste from the Drizzle ORM implementation, which kind of scared me away given that Drizzle is still fairly unstable. I would love to know if there's a more canonical solution to typing these sorts of functions.
icomad
icomadOP•7mo ago
Yeah, at the end I came up with something exactly like your implementation, it will do for now, thank you!

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