fix: Correctly validate relationship enum values in eq, neq and in methods

src/PostgrestFilterBuilder.ts

@@ -1,5 +1,5 @@
 import PostgrestTransformBuilder from './PostgrestTransformBuilder'
-import { GenericSchema } from './types'
+import { GenericSchema, GenericTable } from './types'
 
 type FilterOperator =
   | 'eq'
@@ -25,6 +25,30 @@ type FilterOperator =
   | 'phfts'
   | 'wfts'
 
+// Match relationship filters with `table.column` syntax and resolve underlying column value.
+// If not matched, fallback to generic type.
+type ResolveFilterValue<
+  Tables extends Record<string, GenericTable>,
+  Row extends Record<string, unknown>,
+  ColumnName extends string
+> = ColumnName extends `${infer RelationshipTable}.${infer RelationshipColumn}`
+  ? ResolveFilterRelationshipValue<Tables, RelationshipTable, RelationshipColumn>
+  : ColumnName extends keyof Row
+  ? Row[ColumnName]
+  : never
+
+type ResolveFilterRelationshipValue<
+  Tables extends Record<string, GenericTable>,
+  RelationshipTable extends string,
+  RelationshipColumn extends string
+> = RelationshipTable extends keyof Tables
+  ? 'Row' extends keyof Tables[RelationshipTable]
+    ? RelationshipColumn extends keyof Tables[RelationshipTable]['Row']
+      ? Tables[RelationshipTable]['Row'][RelationshipColumn]
+      : unknown
+    : unknown
+  : unknown
+
 export default class PostgrestFilterBuilder<
   Schema extends GenericSchema,
   Row extends Record<string, unknown>,
@@ -42,7 +66,9 @@ export default class PostgrestFilterBuilder<
    */
   eq<ColumnName extends string>(
     column: ColumnName,
-    value: ColumnName extends keyof Row ? NonNullable<Row[ColumnName]> : NonNullable<unknown>
+    value: ResolveFilterValue<Schema['Tables'], Row, ColumnName> extends never
+      ? NonNullable<unknown>
+      : NonNullable<ResolveFilterValue<Schema['Tables'], Row, ColumnName>>
   ): this {
     this.url.searchParams.append(column, `eq.${value}`)
     return this
@@ -56,7 +82,9 @@ export default class PostgrestFilterBuilder<
    */
   neq<ColumnName extends string>(
     column: ColumnName,
-    value: ColumnName extends keyof Row ? Row[ColumnName] : unknown
+    value: ResolveFilterValue<Schema['Tables'], Row, ColumnName> extends never
+      ? unknown
+      : ResolveFilterValue<Schema['Tables'], Row, ColumnName>
   ): this {
     this.url.searchParams.append(column, `neq.${value}`)
     return this
@@ -234,7 +262,9 @@ export default class PostgrestFilterBuilder<
    */
   in<ColumnName extends string>(
     column: ColumnName,
-    values: ColumnName extends keyof Row ? ReadonlyArray<Row[ColumnName]> : unknown[]
+    values: ResolveFilterValue<Schema['Tables'], Row, ColumnName> extends never
+      ? unknown[]
+      : ReadonlyArray<ResolveFilterValue<Schema['Tables'], Row, ColumnName>>
   ): this {
     const cleanedValues = Array.from(new Set(values))
       .map((s) => {

test/index.test-d.ts

@@ -21,12 +21,26 @@ const postgrest = new PostgrestClient<Database>(REST_URL)
   expectError(postgrest.from('users').select().eq('username', nullableVar))
 }
 
-// `.eq()`, '.neq()' and `.in()` validate value when column is an enum
+// `.eq()`, '.neq()' and `.in()` validate provided filter value when column is an enum.
+// Behaves the same for simple columns, as well as relationship filters.
 {
   expectError(postgrest.from('users').select().eq('status', 'invalid'))
   expectError(postgrest.from('users').select().neq('status', 'invalid'))
   expectError(postgrest.from('users').select().in('status', ['invalid']))
 
+  expectError(
+    postgrest.from('best_friends').select('users!first_user(status)').eq('users.status', 'invalid')
+  )
+  expectError(
+    postgrest.from('best_friends').select('users!first_user(status)').neq('users.status', 'invalid')
+  )
+  expectError(
+    postgrest
+      .from('best_friends')
+      .select('users!first_user(status)')
+      .in('users.status', ['invalid'])
+  )
+
   {
     const { data, error } = await postgrest.from('users').select('status').eq('status', 'ONLINE')
     if (error) {
@@ -53,6 +67,39 @@ const postgrest = new PostgrestClient<Database>(REST_URL)
     }
     expectType<{ status: Database['public']['Enums']['user_status'] | null }[]>(data)
   }
+
+  {
+    const { data, error } = await postgrest
+      .from('best_friends')
+      .select('users!first_user(status)')
+      .eq('users.status', 'ONLINE')
+    if (error) {
+      throw new Error(error.message)
+    }
+    expectType<{ users: { status: Database['public']['Enums']['user_status'] | null } }[]>(data)
+  }
+
+  {
+    const { data, error } = await postgrest
+      .from('best_friends')
+      .select('users!first_user(status)')
+      .neq('users.status', 'ONLINE')
+    if (error) {
+      throw new Error(error.message)
+    }
+    expectType<{ users: { status: Database['public']['Enums']['user_status'] | null } }[]>(data)
+  }
+
+  {
+    const { data, error } = await postgrest
+      .from('best_friends')
+      .select('users!first_user(status)')
+      .in('users.status', ['ONLINE', 'OFFLINE'])
+    if (error) {
+      throw new Error(error.message)
+    }
+    expectType<{ users: { status: Database['public']['Enums']['user_status'] | null } }[]>(data)
+  }
 }
 
 // can override result type