[#17689] - read back the generated id when the identity is 0 on adapters without sequences

CHANGELOG-5.0.md

@@ -22,6 +22,7 @@ All notable changes are documented here. The format is based on [Keep a Changelo
 ### Fixed
 
 - `Phalcon\Db\Adapter\Pdo\Postgresql::describeReferences()` returning wrong column pairs for composite foreign keys. [#17680](https://github.com/phalcon/cphalcon/issues/17680)
+- `Phalcon\Mvc\Model::doLowInsert()` not reading back the generated id on MySQL when the identity property is `0`. [#17689](https://github.com/phalcon/cphalcon/issues/17689)
 - `Phalcon\Mvc\View\Engine\Volt\Compiler::compile()` rendering serialized blocks for the second child of a layout when `stat` is `false`. [#17674](https://github.com/phalcon/cphalcon/issues/17674)
 - `Phalcon\Mvc\View\Engine\Volt\Compiler::compileCall()` silently dropping `{% call %}` blocks instead of throwing an exception. [#17676](https://github.com/phalcon/cphalcon/issues/17676)
 - PHP 8.6 deprecation for session handlers without `create_sid()`: `Phalcon\Session\Adapter\AbstractAdapter` and `Phalcon\Session\Adapter\Noop` now implement `SessionIdInterface` and `create_sid()`. [#17687](https://github.com/phalcon/cphalcon/issues/17687)

phalcon/Mvc/Model.zep

@@ -4690,7 +4690,7 @@ abstract class Model extends AbstractInjectionAware implements EntityInterface,
             unsetDefaultValues = [],
             value              = null,
             values             = [];
-        bool useExplicitIdentity;
+        bool useExplicitIdentity, useSequences;
 
         let bindSkip            = Column::BIND_SKIP,
             manager             = <ManagerInterface> this->modelsManager,
@@ -4880,9 +4880,10 @@ abstract class Model extends AbstractInjectionAware implements EntityInterface,
             /**
              * We check if the model have sequences
              */
-            let sequenceName = null;
+            let sequenceName = null,
+                useSequences = (bool) connection->supportSequences();
 
-            if connection->supportSequences() {
+            if useSequences {
                 if method_exists(this, "getSequenceName") {
                     let sequenceName = this->{"getSequenceName"}();
                 } else {
@@ -4903,10 +4904,12 @@ abstract class Model extends AbstractInjectionAware implements EntityInterface,
              * used, so calling lastInsertId() would fail on PostgreSQL because
              * currval() requires nextval() to have been called in the session.
              * Reuse the value already present on the model in that case.
+             * Without sequences, lastInsertId() returns the stored id. MySQL
+             * can replace 0 with a generated id.
              */
             fetch value, this->{attributeField};
 
-            if value !== null && value !== "" {
+            if value !== null && value !== "" && (useSequences || value != 0) {
                 let lastInsertedId = value;
             } else {
                 let lastInsertedId = connection->lastInsertId(sequenceName);

tests/database/Mvc/Model/CreateTest.php

@@ -18,6 +18,7 @@
 use Phalcon\Tests\Support\Migrations\InvoicesMigration;
 use Phalcon\Tests\Support\Models\Invoices;
 use Phalcon\Tests\Support\Traits\DiTrait;
+use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\Group;
 
 use function date;
@@ -37,6 +38,17 @@ public function setUp(): void
         (new InvoicesMigration($connection));
     }
 
+    /**
+     * @return array<string, array{0: int|string}>
+     */
+    public static function zeroIdentityProvider(): array
+    {
+        return [
+            'int'    => [0],
+            'string' => ['0'],
+        ];
+    }
+
     /**
      * @author Phalcon Team <team@phalcon.io>
      * @since  2020-02-01
@@ -150,6 +162,30 @@ public function testMvcModelCreateAutoIncrementAfterExplicitIdPgsql(): void
         $this->assertGreaterThan(77, (int) $second->inv_id);
     }
 
+    /**
+     * An explicit identity value is kept as set on the model (same value and
+     * type) on MySQL and SQLite.
+     *
+     * @issue  https://github.com/phalcon/cphalcon/issues/17689
+     * @author Phalcon Team <team@phalcon.io>
+     * @since  2026-10-22
+     */
+    #[Group('mysql')]
+    #[Group('sqlite')]
+    public function testMvcModelCreateWithExplicitIdMysqlSqlite(): void
+    {
+        $invoice                  = new Invoices();
+        $invoice->inv_id          = 77;
+        $invoice->inv_cst_id      = 2;
+        $invoice->inv_status_flag = 1;
+        $invoice->inv_title       = uniqid('inv-');
+        $invoice->inv_total       = 50.00;
+        $invoice->inv_created_at  = date('Y-m-d H:i:s');
+
+        $this->assertNotFalse($invoice->create());
+        $this->assertSame(77, $invoice->inv_id);
+    }
+
     /**
      * Inserting with an explicit primary key on PostgreSQL must not throw a
      * "currval of sequence not yet defined in this session" error.
@@ -175,4 +211,64 @@ public function testMvcModelCreateWithExplicitIdPgsql(): void
         $this->assertNotFalse($result);
         $this->assertSame(77, (int) $invoice->inv_id);
     }
+
+    /**
+     * On MySQL, an identity left at 0 is replaced by a generated id; the
+     * model must read it back with lastInsertId() instead of keeping 0.
+     * Assumes the default sql_mode (no NO_AUTO_VALUE_ON_ZERO).
+     *
+     * @issue  https://github.com/phalcon/cphalcon/issues/17689
+     * @author Phalcon Team <team@phalcon.io>
+     * @since  2026-10-22
+     */
+    #[DataProvider('zeroIdentityProvider')]
+    #[Group('mysql')]
+    public function testMvcModelCreateWithZeroIdentityMysql(int|string $zero): void
+    {
+        $invoice                  = new Invoices();
+        $invoice->inv_id          = $zero;
+        $invoice->inv_cst_id      = 2;
+        $invoice->inv_status_flag = 1;
+        $invoice->inv_title       = uniqid('inv-');
+        $invoice->inv_total       = 50.00;
+        $invoice->inv_created_at  = date('Y-m-d H:i:s');
+
+        $this->assertNotFalse($invoice->create());
+
+        $stored = Invoices::findFirst();
+
+        $this->assertNotNull($stored);
+        $this->assertGreaterThan(0, (int) $stored->inv_id);
+        $this->assertEquals($stored->inv_id, $invoice->inv_id);
+        $this->assertSame((int) $stored->inv_id, (int) $invoice->inv_id);
+    }
+
+    /**
+     * On SQLite, an identity of 0 is stored as given; the model reads it
+     * back with lastInsertId(), which returns it as a string.
+     *
+     * @issue  https://github.com/phalcon/cphalcon/issues/17689
+     * @author Phalcon Team <team@phalcon.io>
+     * @since  2026-10-26
+     */
+    #[DataProvider('zeroIdentityProvider')]
+    #[Group('sqlite')]
+    public function testMvcModelCreateWithZeroIdentitySqlite(int|string $zero): void
+    {
+        $invoice                  = new Invoices();
+        $invoice->inv_id          = $zero;
+        $invoice->inv_cst_id      = 2;
+        $invoice->inv_status_flag = 1;
+        $invoice->inv_title       = uniqid('inv-');
+        $invoice->inv_total       = 50.00;
+        $invoice->inv_created_at  = date('Y-m-d H:i:s');
+
+        $this->assertNotFalse($invoice->create());
+
+        $stored = Invoices::findFirst();
+
+        $this->assertNotNull($stored);
+        $this->assertSame(0, (int) $stored->inv_id);
+        $this->assertSame('0', $invoice->inv_id);
+    }
 }