feat: ✨ Adds "relationships" to the /tables endpoint

This change provides an array of relationships in both directions, the "source" and the "target". Each table will include this array, so that we can map relationships in both directions

Author: kiwicopple

dist/lib/sql/tables/list.sql

@@ -87,6 +87,24 @@ WHERE
   AND pg_class.relnamespace = pg_namespace.oid
   AND pg_attribute.attrelid = pg_class.oid
   AND pg_attribute.attnum = any(pg_index.indkey)
+),
+relationships as (
+  select
+    (tc.table_schema || '.' || (tc.table_name)) as source_table_id,
+    tc.table_schema as source_schema,
+    tc.table_name as source_table_name,
+    kcu.column_name as source_column_name,
+    (ccu.table_schema || '.' || (ccu.table_name)) as target_table_id,
+    ccu.table_schema AS target_table_schema,
+    ccu.table_name AS target_table_name,
+    ccu.column_name AS target_column_name,
+    tc.constraint_name
+  FROM
+    information_schema.table_constraints AS tc
+    JOIN information_schema.key_column_usage AS kcu USING (constraint_schema, constraint_name)
+    JOIN information_schema.constraint_column_usage AS ccu USING (constraint_schema, constraint_name)
+  where
+    tc.constraint_type = 'FOREIGN KEY'
 )
 SELECT 
   *,
@@ -135,7 +153,24 @@ SELECT
         WHERE
           pk_list.table_id = tables.table_id
       ) primary_keys
-  ),
-  '[]'
-) AS primary_keys
+    ),
+    '[]'
+  ) AS primary_keys,
+  COALESCE(
+  (
+    SELECT
+      array_to_json(array_agg(row_to_json(relationships)))
+    FROM
+      (
+        SELECT
+          *
+        FROM
+          relationships
+        WHERE
+          relationships.source_table_id = tables.table_id
+          OR relationships.target_table_id = tables.table_id
+      ) relationships
+    ),
+    '[]'
+  ) AS relationships
 FROM tables

src/lib/interfaces/tables.ts

@@ -9,6 +9,19 @@ export namespace Tables {
     is_typed: boolean
     bytes: number
     size: string
+    relationships: Relationship[]
+  }
+
+  export interface Relationship {
+    source_table_id: string
+    source_schema: string
+    source_table_name: string
+    source_column_name: string
+    target_table_id: string
+    target_table_schema: string
+    target_table_name: string
+    target_column_name: string
+    constraint_name: string
   }
 
 }

src/lib/sql/tables/list.sql

@@ -87,6 +87,24 @@ WHERE
   AND pg_class.relnamespace = pg_namespace.oid
   AND pg_attribute.attrelid = pg_class.oid
   AND pg_attribute.attnum = any(pg_index.indkey)
+),
+relationships as (
+  select
+    (tc.table_schema || '.' || (tc.table_name)) as source_table_id,
+    tc.table_schema as source_schema,
+    tc.table_name as source_table_name,
+    kcu.column_name as source_column_name,
+    (ccu.table_schema || '.' || (ccu.table_name)) as target_table_id,
+    ccu.table_schema AS target_table_schema,
+    ccu.table_name AS target_table_name,
+    ccu.column_name AS target_column_name,
+    tc.constraint_name
+  FROM
+    information_schema.table_constraints AS tc
+    JOIN information_schema.key_column_usage AS kcu USING (constraint_schema, constraint_name)
+    JOIN information_schema.constraint_column_usage AS ccu USING (constraint_schema, constraint_name)
+  where
+    tc.constraint_type = 'FOREIGN KEY'
 )
 SELECT 
   *,
@@ -135,7 +153,24 @@ SELECT
         WHERE
           pk_list.table_id = tables.table_id
       ) primary_keys
-  ),
-  '[]'
-) AS primary_keys
+    ),
+    '[]'
+  ) AS primary_keys,
+  COALESCE(
+  (
+    SELECT
+      array_to_json(array_agg(row_to_json(relationships)))
+    FROM
+      (
+        SELECT
+          *
+        FROM
+          relationships
+        WHERE
+          relationships.source_table_id = tables.table_id
+          OR relationships.target_table_id = tables.table_id
+      ) relationships
+    ),
+    '[]'
+  ) AS relationships
 FROM tables

test/integration/index.spec.js

@@ -145,6 +145,14 @@ describe('/tables', async () => {
     const datum = tables.data.find((x) => x.table_id == 'public.users')
     assert.equal(datum.grants.length > 0, true)
   })
+  it('should return the relationships', async () => {
+    const tables = await axios.get(`${URL}/tables`)
+    const datum = tables.data.find((x) => x.table_id == 'public.users')
+    const relationships = datum.relationships
+    const relationship = relationships.find(x => x.source_table_id == 'public.todos')
+    assert.equal(relationships.length > 0, true)
+    assert.equal(true, relationship.target_table_id == 'public.users')
+  })
 
   it('GET with system tables', async () => {
     const res = await axios.get(`${URL}/tables?includeSystemSchemas=true`)