From ed50842cbebe1f1a299126ad41b66fe37517883c Mon Sep 17 00:00:00 2001
From: yzxcj797 <1784931579@qq.com>
Date: Wed, 19 Aug 2026 00:32:52 +0800
Subject: [PATCH] Preserve nested PostgreSQL function defaults

Recursively serialize function arguments and casts when converting PostgreSQL default expressions. This keeps nested functions such as the pg_dump default from issue #431 intact instead of dropping their arguments.
---
 package.json                         |  3 ++-
 src/utils/importSQL/postgres.js      | 20 +++------------
 src/utils/importSQL/postgres.test.js | 38 ++++++++++++++++++++++++++++
 src/utils/importSQL/shared.js        | 29 ++++++++-------------
 4 files changed, 54 insertions(+), 36 deletions(-)
 create mode 100644 src/utils/importSQL/postgres.test.js

diff --git a/package.json b/package.json
index 848104764..68f03fa92 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,8 @@
     "dev": "vite",
     "build": "vite build",
     "lint": "eslint . --ext js,jsx --report-unused-disable-directives --max-warnings 0",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "test": "node --test"
   },
   "dependencies": {
     "@dagrejs/dagre": "^3.1.1",
diff --git a/src/utils/importSQL/postgres.js b/src/utils/importSQL/postgres.js
index ddee8b90b..8c73649c9 100644
--- a/src/utils/importSQL/postgres.js
+++ b/src/utils/importSQL/postgres.js
@@ -75,22 +75,10 @@ export function fromPostgres(ast, diagramDb = DB.GENERIC) {
             if (d.default_val) {
               let defaultValue = "";
               if (d.default_val.value.type === "function") {
-                defaultValue = d.default_val.value.name.name[0].value;
-                if (d.default_val.value.args) {
-                  defaultValue +=
-                    "(" +
-                    d.default_val.value.args.value
-                      .map((v) => {
-                        if (
-                          v.type === "single_quote_string" ||
-                          v.type === "double_quote_string"
-                        )
-                          return "'" + v.value + "'";
-                        return v.value;
-                      })
-                      .join(", ") +
-                    ")";
-                }
+                defaultValue = buildSQLFromAST(
+                  d.default_val.value,
+                  DB.POSTGRES,
+                );
               } else if (d.default_val.value.type === "null") {
                 defaultValue = "NULL";
               } else if (d.default_val.value.type === "cast") {
diff --git a/src/utils/importSQL/postgres.test.js b/src/utils/importSQL/postgres.test.js
new file mode 100644
index 000000000..f071f8575
--- /dev/null
+++ b/src/utils/importSQL/postgres.test.js
@@ -0,0 +1,38 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import parserPackage from "node-sql-parser";
+import { createServer } from "vite";
+
+const { Parser } = parserPackage;
+
+const vite = await createServer({
+  appType: "custom",
+  configFile: false,
+  logLevel: "error",
+  optimizeDeps: { noDiscovery: true },
+  server: { middlewareMode: true },
+});
+
+try {
+  const { fromPostgres } = await vite.ssrLoadModule(
+    "/src/utils/importSQL/postgres.js",
+  );
+
+  test("preserves nested function defaults when importing PostgreSQL", () => {
+    const sql = `CREATE TABLE public.person (
+      id bigint NOT NULL,
+      external_id character varying(255)
+        DEFAULT "substring"(md5((random())::text), 1, 6)
+    );`;
+    const ast = new Parser().astify(sql, { database: "postgresql" });
+
+    const diagram = fromPostgres(ast);
+    const field = diagram.tables[0].fields.find(
+      (field) => field.name === "external_id",
+    );
+
+    assert.equal(field.default, "substring(md5(random()::TEXT), 1, 6)");
+  });
+} finally {
+  await vite.close();
+}
diff --git a/src/utils/importSQL/shared.js b/src/utils/importSQL/shared.js
index 521a22fbc..9c113f0a3 100644
--- a/src/utils/importSQL/shared.js
+++ b/src/utils/importSQL/shared.js
@@ -29,25 +29,16 @@ export function buildSQLFromAST(ast, db = DB.MYSQL) {
   }
 
   if (ast.type === "function") {
-    let expr = "";
-    expr = ast.name;
-    if (ast.args) {
-      expr +=
-        "(" +
-        ast.args.value
-          .map((v) => {
-            if (v.type === "column_ref") return "`" + v.column + "`";
-            if (
-              v.type === "single_quote_string" ||
-              v.type === "double_quote_string"
-            )
-              return "'" + v.value + "'";
-            return v.value;
-          })
-          .join(", ") +
-        ")";
-    }
-    return expr;
+    const name = Array.isArray(ast.name?.name)
+      ? ast.name.name.map((part) => part.value).join(".")
+      : ast.name;
+    const args = Array.isArray(ast.args?.value)
+      ? ast.args.value.map((arg) => buildSQLFromAST(arg, db)).join(", ")
+      : "";
+    return `${name}(${args})`;
+  } else if (ast.type === "cast") {
+    const type = (ast.target ?? []).map((target) => target.dataType).join(", ");
+    return `${buildSQLFromAST(ast.expr, db)}::${type}`;
   } else if (ast.type === "column_ref") {
     return quoteColumn(ast.column, db);
   } else if (ast.type === "expr_list") {