fix(types): handle many-to-many join tables references

Author: avallete

src/select-query-parser/utils.ts

@@ -12,6 +12,8 @@ import {
 
 export type SelectQueryError<Message extends string> = { error: true } & Message
 
+type AsString<T> = T extends string ? T : ''
+
 type RequireHintingSelectQueryError<
   DistantName extends string,
   RelationName extends string
@@ -413,9 +415,58 @@ type ResolveForwardRelationship<
       relation: FoundByMatch
       direction: 'forward'
       from: CurrentTableOrView
-      type: 'found-my-match'
+      type: 'found-by-match'
+    }
+  : // Forward relations can also alias other tables via tables joins relationships
+  // in such cases we crawl all the tables looking for a join table between our current table
+  // and the Field['name'] desired desitnation
+  FindJoinTableRelationship<
+      Schema,
+      CurrentTableOrView,
+      Field['name']
+    > extends infer FoundByJoinTable extends GenericRelationship
+  ? {
+      referencedTable: TablesAndViews<Schema>[FoundByJoinTable['referencedRelation']]
+      relation: FoundByJoinTable & { match: 'refrel' }
+      direction: 'forward'
+      from: CurrentTableOrView
+      type: 'found-by-join-table'
     }
-  : SelectQueryError<'could not find the relation'>
+  : SelectQueryError<`could not find the relation between ${AsString<CurrentTableOrView>} and ${Field['name']}`>
+
+/**
+ * Given a CurrentTableOrView, finds all join tables to this relation.
+ * For example, if products and categories are linked via product_categories table:
+ *
+ * @example
+ * Given:
+ * - CurrentTableView = 'products'
+ * - FieldName = "categories"
+ *
+ * It should return this relationship from product_categories:
+ * {
+ *   foreignKeyName: "product_categories_category_id_fkey",
+ *   columns: ["category_id"],
+ *   isOneToOne: false,
+ *   referencedRelation: "categories",
+ *   referencedColumns: ["id"]
+ * }
+ */
+export type FindJoinTableRelationship<
+  Schema extends GenericSchema,
+  CurrentTableOrView extends keyof TablesAndViews<Schema>,
+  FieldName extends string
+> = {
+  [TableName in keyof TablesAndViews<Schema>]: TablesAndViews<Schema>[TableName]['Relationships'] extends readonly (infer Rel)[]
+    ? Rel extends { referencedRelation: CurrentTableOrView }
+      ? TablesAndViews<Schema>[TableName]['Relationships'] extends readonly (infer OtherRel)[]
+        ? OtherRel extends { referencedRelation: FieldName }
+          ? OtherRel
+          : never
+        : never
+      : never
+    : never
+}[keyof TablesAndViews<Schema>]
 
 /**
  * Finds a matching relationship based on the FieldNode's name and optional hint.

test/db/00-schema.sql

@@ -73,6 +73,31 @@ FOREIGN KEY (parent_id)
 REFERENCES public.collections(id);
 COMMENT ON COLUMN public.messages.data IS 'For unstructured data and prototyping.';
 
+-- MANY-TO-MANY RELATIONSHIP USING A JOIN TABLE
+
+-- Create a table for products
+CREATE TABLE public.products (
+  id bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+  name text NOT NULL,
+  description text,
+  price decimal(10, 2) NOT NULL
+);
+
+-- Create a table for categories
+CREATE TABLE public.categories (
+  id bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+  name text NOT NULL,
+  description text
+);
+
+-- Create a join table for the many-to-many relationship between products and categories
+CREATE TABLE public.product_categories (
+  product_id bigint REFERENCES public.products(id) ON DELETE CASCADE,
+  category_id bigint REFERENCES public.categories(id) ON DELETE CASCADE,
+  PRIMARY KEY (product_id, category_id)
+);
+
+
 -- STORED FUNCTION
 CREATE FUNCTION public.get_status(name_param text)
 RETURNS user_status AS $$

test/db/01-dummy-data.sql

@@ -58,3 +58,26 @@ VALUES
   (4, 'Grandchild', 2),
   (5, 'Sibling of Grandchild', 2),
   (6, 'Child of Another Root', 3);
+
+-- Insert sample products
+INSERT INTO public.products (id, name, description, price)
+VALUES
+  (1, 'Laptop', 'High-performance laptop', 999.99),
+  (2, 'Smartphone', 'Latest model smartphone', 699.99),
+  (3, 'Headphones', 'Noise-cancelling headphones', 199.99);
+
+-- Insert sample categories
+INSERT INTO public.categories (id, name, description)
+VALUES
+  (1, 'Electronics', 'Electronic devices and gadgets'),
+  (2, 'Computers', 'Computer and computer accessories'),
+  (3, 'Audio', 'Audio equipment');
+
+-- Insert product-category relationships
+INSERT INTO public.product_categories (product_id, category_id)
+VALUES
+  (1, 1), -- Laptop is in Electronics
+  (1, 2), -- Laptop is also in Computers
+  (2, 1), -- Smartphone is in Electronics
+  (3, 1), -- Headphones are in Electronics
+  (3, 3); -- Headphones are also in Audio

test/relationships.ts

@@ -181,6 +181,10 @@ export const selectParams = {
     from: 'users',
     select: 'alias:missing_column.count()',
   },
+  manyToManyWithJoinTable: {
+    from: 'products',
+    select: '*, categories(*)',
+  },
 } as const
 
 export const selectQueries = {
@@ -356,6 +360,9 @@ export const selectQueries = {
   aggregateOnMissingColumnWithAlias: postgrest
     .from(selectParams.aggregateOnMissingColumnWithAlias.from)
     .select(selectParams.aggregateOnMissingColumnWithAlias.select),
+  manyToManyWithJoinTable: postgrest
+    .from(selectParams.manyToManyWithJoinTable.from)
+    .select(selectParams.manyToManyWithJoinTable.select),
 } as const
 
 test('nested query with selective fields', async () => {
@@ -1831,3 +1838,33 @@ test('aggregate on missing column with alias', async () => {
     }
   `)
 })
+
+test('many-to-many with join table', async () => {
+  const res = await selectQueries.manyToManyWithJoinTable.eq('id', 1).single()
+  expect(res).toMatchInlineSnapshot(`
+    Object {
+      "count": null,
+      "data": Object {
+        "categories": Array [
+          Object {
+            "description": "Electronic devices and gadgets",
+            "id": 1,
+            "name": "Electronics",
+          },
+          Object {
+            "description": "Computer and computer accessories",
+            "id": 2,
+            "name": "Computers",
+          },
+        ],
+        "description": "High-performance laptop",
+        "id": 1,
+        "name": "Laptop",
+        "price": 999.99,
+      },
+      "error": null,
+      "status": 200,
+      "statusText": "OK",
+    }
+  `)
+})

test/select-query-parser/select.test-d.ts

@@ -742,3 +742,21 @@ type Schema = Database['public']
   if (error) throw error
   expectType<`column 'missing_column' does not exist on 'users'.`>(data)
 }
+
+// many-to-many with join table
+{
+  const { data } = await selectQueries.manyToManyWithJoinTable.limit(1).single()
+  let result: Exclude<typeof data, null>
+  let expected: {
+    id: number
+    name: string
+    description: string | null
+    price: number
+    categories: {
+      id: number
+      name: string
+      description: string | null
+    }[]
+  }
+  expectType<TypeEqual<typeof result, typeof expected>>(true)
+}

test/select-query-parser/types.test-d.ts

@@ -10,6 +10,7 @@ import { TypeEqual } from 'ts-expect'
 import {
   FindMatchingTableRelationships,
   IsRelationNullable,
+  FindJoinTableRelationship,
 } from '../../src/select-query-parser/utils'
 import { Json } from '../../src/select-query-parser/types'
 import { ParseQuery } from '../../src/select-query-parser/parser'
@@ -124,11 +125,8 @@ import { ParseQuery } from '../../src/select-query-parser/parser'
   type Row = Schema['Tables'][RelationName]['Row']
   type Relationships = Schema['Tables'][RelationName]['Relationships']
   type ParsedQuery = ParseQuery<typeof select>
-  // First field of the query is username and is properly parsed
-  type f1 = ParsedQuery[0]
   type r1 = ProcessNode<Schema, Row, RelationName, Relationships, ParsedQuery[0]>
   expectType<TypeEqual<r1, { username: string }>>(true)
-  type f2 = ParsedQuery[1]
   type r2 = ProcessNodes<Schema, Row, RelationName, Relationships, ParsedQuery>
   // fail because result for messages is ({id: string} | {message: string | null })[]
   expectType<
@@ -160,3 +158,42 @@ import { ParseQuery } from '../../src/select-query-parser/parser'
   type r2 = ProcessNodes<Schema, Row, RelationName, Relationships, ParsedQuery>
   expectType<r2>(expected!)
 }
+
+{
+  type Schema = Database['public']
+  type CurrentTableOrView = 'products'
+  type FieldName = 'categories'
+  type R = FindJoinTableRelationship<Schema, CurrentTableOrView, FieldName>
+  let expected: {
+    foreignKeyName: 'product_categories_category_id_fkey'
+    columns: ['category_id']
+    isOneToOne: false
+    referencedRelation: 'categories'
+    referencedColumns: ['id']
+  }
+  expectType<R>(expected!)
+}
+
+{
+  type Schema = Database['public']
+  type CurrentTableOrView = 'categories'
+  type FieldName = 'products'
+  type R = FindJoinTableRelationship<Schema, CurrentTableOrView, FieldName>
+  let expected: {
+    foreignKeyName: 'product_categories_product_id_fkey'
+    columns: ['product_id']
+    isOneToOne: false
+    referencedRelation: 'products'
+    referencedColumns: ['id']
+  }
+  expectType<R>(expected!)
+}
+
+{
+  type Schema = Database['public']
+  type CurrentTableOrView = 'categories'
+  type FieldName = 'missing'
+  type R = FindJoinTableRelationship<Schema, CurrentTableOrView, FieldName>
+  let expected: never
+  expectType<R>(expected!)
+}

test/types.ts

@@ -250,6 +250,75 @@ export type Database = {
           }
         ]
       }
+      product_categories: {
+        Row: {
+          category_id: number
+          product_id: number
+        }
+        Insert: {
+          category_id: number
+          product_id: number
+        }
+        Update: {
+          category_id?: number
+          product_id?: number
+        }
+        Relationships: [
+          {
+            foreignKeyName: 'product_categories_category_id_fkey'
+            columns: ['category_id']
+            isOneToOne: false
+            referencedRelation: 'categories'
+            referencedColumns: ['id']
+          },
+          {
+            foreignKeyName: 'product_categories_product_id_fkey'
+            columns: ['product_id']
+            isOneToOne: false
+            referencedRelation: 'products'
+            referencedColumns: ['id']
+          }
+        ]
+      }
+      products: {
+        Row: {
+          description: string | null
+          id: number
+          name: string
+          price: number
+        }
+        Insert: {
+          description?: string | null
+          id?: number
+          name: string
+          price: number
+        }
+        Update: {
+          description?: string | null
+          id?: number
+          name?: string
+          price?: number
+        }
+        Relationships: []
+      }
+      categories: {
+        Row: {
+          description: string | null
+          id: number
+          name: string
+        }
+        Insert: {
+          description?: string | null
+          id?: number
+          name: string
+        }
+        Update: {
+          description?: string | null
+          id?: number
+          name?: string
+        }
+        Relationships: []
+      }
       shops: {
         Row: {
           address: string | null