fix: options merging bug what caused missing migrations error message with mysql

Author: rrd108

src/module.ts

@@ -60,7 +60,13 @@ export default defineNuxtModule<RuntimeModuleOptions>({
 
     // Add runtime config (server-side)
     // Priority: runtimeConfig (strongest) > top-level app config > default options (weakest)
-    const runtimeConfigOptions = defu(nuxt.options.runtimeConfig.nuxtUsers || {}, options, defaultOptions) as ModuleOptions
+    // Exclude connector from defaults to prevent mixing MySQL/PostgreSQL with SQLite settings
+    const { connector: _defaultConnector, ...defaultsWithoutConnector } = defaultOptions
+    const runtimeConfigOptions = defu(nuxt.options.runtimeConfig.nuxtUsers || {}, options, defaultsWithoutConnector) as ModuleOptions
+    
+    // Use the configured connector or fallback to default (don't merge connector options)
+    const configuredConnector = (nuxt.options.runtimeConfig.nuxtUsers as ModuleOptions)?.connector || options.connector
+    runtimeConfigOptions.connector = configuredConnector || defaultOptions.connector
 
     nuxt.options.runtimeConfig.nuxtUsers = {
       ...runtimeConfigOptions,

test/unit/module.connector-merging.test.ts

@@ -0,0 +1,64 @@
+import { describe, it, expect } from 'vitest'
+import { defu } from 'defu'
+import { defaultOptions } from '../../src/module'
+import type { ModuleOptions } from '../../src/types'
+
+/**
+ * Test to demonstrate the connector merging bug in module.ts
+ *
+ * When a user configures MySQL in runtimeConfig, defu merges it with defaultOptions
+ * which contains SQLite settings, resulting in MySQL config having a 'path' property.
+ */
+describe('Module connector merging bug', () => {
+  it('should demonstrate how defu mixes MySQL and SQLite configs (OLD BEHAVIOR)', () => {
+    // Simulate what the user has in their nuxt.config.ts
+    const userRuntimeConfig = {
+      connector: {
+        name: 'mysql' as const,
+        options: {
+          host: 'localhost',
+          port: 3306,
+          user: '',
+          password: '',
+          database: ''
+        }
+      }
+    }
+
+    // This is the OLD way (before the fix) - directly merging with defaultOptions
+    const runtimeConfigOptions = defu(userRuntimeConfig, {}, defaultOptions) as ModuleOptions
+
+    // BUG: The merged config INCORRECTLY has a path property for MySQL
+    console.log('Merged connector options (old way):', runtimeConfigOptions.connector.options)
+
+    // This demonstrates the bug - path should be undefined for MySQL but isn't
+    expect(runtimeConfigOptions.connector.options.path).toBe('./data/users.sqlite3')
+  })
+
+  it('should show the correct way to merge without mixing connectors', () => {
+    const userRuntimeConfig = {
+      connector: {
+        name: 'mysql' as const,
+        options: {
+          host: 'localhost',
+          port: 3306,
+          user: '',
+          password: '',
+          database: ''
+        }
+      }
+    }
+
+    // FIX: Exclude connector from defaults before merging
+    const { connector: _defaultConnector, ...defaultsWithoutConnector } = defaultOptions
+    const runtimeConfigOptions = defu(userRuntimeConfig, {}, defaultsWithoutConnector) as ModuleOptions
+
+    // Use the configured connector (don't merge with default)
+    runtimeConfigOptions.connector = userRuntimeConfig.connector || defaultOptions.connector
+
+    // This should pass - MySQL config should not have SQLite path
+    expect(runtimeConfigOptions.connector.options.path).toBeUndefined()
+    expect(runtimeConfigOptions.connector.name).toBe('mysql')
+    expect(runtimeConfigOptions.connector.options.host).toBe('localhost')
+  })
+})