fix: select from nested join expression (#287)

* fix: properly retrieve join expression name

Ensure that the join expression name is correctly retrieved by using a recursive function to handle nested joins.

* changeset

Author: Newbie012

.changeset/forty-tips-leave.md

@@ -0,0 +1,5 @@
+---
+"@ts-safeql/generate": patch
+---
+
+Fixed an issue when selecting from nested join expressions

packages/generate/src/generate.test.ts

@@ -1245,6 +1245,37 @@ test("select union select", async () => {
   });
 });
 
+test("join inside join without an alias", async () => {
+  await testQuery({
+    query: `
+      SELECT cc.caregiver_id
+      FROM caregiver c
+      LEFT JOIN (
+        caregiver_certification cc
+        INNER JOIN caregiver_phonenumber cp
+        ON cp.caregiver_id = cc.caregiver_id
+      ) ON cc.caregiver_id = c.id;
+    `,
+    expected: [["caregiver_id", { kind: "type", value: "number" }]],
+  });
+});
+
+test("join inside join without an alias (duplicate columns)", async () => {
+  await testQuery({
+    query: `
+      SELECT *
+      FROM caregiver c
+      LEFT JOIN (
+        caregiver_certification cc
+        INNER JOIN caregiver_phonenumber cp
+        ON cp.caregiver_id = cc.caregiver_id
+      ) ON cc.caregiver_id = c.id;
+    `,
+    expectedError:
+      "Duplicate columns: caregiver_certification.caregiver_id, caregiver_phonenumber.caregiver_id",
+  });
+});
+
 test("should distinguish between schema", async () => {
   await testQuery({
     query: `SELECT name FROM table1`,

packages/generate/src/utils/get-relations-with-joins.ts

@@ -26,15 +26,22 @@ export function getRelationsWithJoins(parsed: LibPgQueryAST.ParseResult): Relati
   return results;
 }
 
+function recursiveGetJoinName(joinExpr: LibPgQueryAST.JoinExpr): string | undefined {
+  if (joinExpr.rarg?.JoinExpr !== undefined) {
+    return recursiveGetJoinName(joinExpr.rarg.JoinExpr);
+  }
+
+  return joinExpr.rarg?.RangeVar?.relname ?? joinExpr.rarg?.RangeSubselect?.alias?.aliasname;
+}
+
 function recursiveTraverseJoins(
   joins: Join[],
   joinExpr: LibPgQueryAST.JoinExpr,
 ): {
   relName: string;
   joins: Join[];
 } {
-  const joinName =
-    joinExpr.rarg?.RangeVar?.relname ?? joinExpr.rarg?.RangeSubselect?.alias?.aliasname;
+  const joinName = recursiveGetJoinName(joinExpr);
   const aliasName = joinExpr.rarg?.RangeVar?.alias?.aliasname;
 
   if (joinName === undefined) {