feat: query parser: add types for count

Closes #447, #479.

Author: bnjmnt4n

src/select-query-parser.ts

@@ -254,6 +254,8 @@ type ConstructFieldDefinition<
   : Field extends { name: string; original: string }
   ? Field['original'] extends keyof Row
     ? { [K in Field['name']]: Row[Field['original']] }
+    : Field['original'] extends 'count'
+    ? { count: number }
     : SelectQueryError<`Referencing missing column \`${Field['original']}\``>
   : Record<string, unknown>
 

test/index.test-d.ts

@@ -53,6 +53,16 @@ const postgrest = new PostgrestClient<Database>(REST_URL)
   expectError(postgrest.from('updatable_view').update({ non_updatable_column: 0 }))
 }
 
+// `count` in embedded resource
+{
+  const { data, error } = await postgrest.from('messages').select('message, users(count)').single()
+  if (error) {
+    throw new Error(error.message)
+  }
+  // TODO: more accurate type with correct cardinality.
+  expectType<{ message: string | null; users: { count: number } | null }>(data)
+}
+
 // json accessor in select query
 {
   const { data, error } = await postgrest