- Qt Creator Manual
- Using QML Modules with Plugins
- Qt Creator Manual 8.0.2

UI Files ◦ Developing Widget Based Applications

# Using QML Modules with Plugins

QML modules may use C++ plugins to expose components defined in C++ to QML applications.

To create a QML module:

1. Create custom components and place all the `.qml` files in a directory dedicated to your module. For example: `imports\asset_imports`.
2. For Qt Quick UI projects (.qmlproject), specify the path to the directory that contains the module in the .qmlproject file of the application where you want to use the module as a value of the `importPaths` variable. For example `importPaths: [ "imports", "asset_imports" ]`.
3. Create a `qmldir` file for your module and place it in the module directory. For more information, see Module Definition qmldir Files.
4. Create a `qmltypes` file, as instructed in Generating Type Description Files.
5. Create a directory named `designer` in your module directory.
6. Create a `.metainfo` file for your module and place it in the `designer` directory. Use a metainfo file delivered with Qt, such as `qtquickcontrols2.metainfo`, as an example.
7. Import the module into the project, as instructed in Importing QML Modules.

## Generating Type Description Files

When registering QML types, make sure that the QML module has a `plugins.qmltypes` file. Ideally, it should be located in the same directory as the `qmldir` file. The `qmltypes` file contains a description of the components exported by the module's plugins and is loaded by Qt Creator when the module is imported.

For more information, see Type Description Files.

### Dumping Plugins Automatically

If a module with plugins lacks the `qmltypes` file, Qt Creator tries to generate a temporary file itself by running the `qmldump` program in the background. However, this automatic dumping is a fallback mechanism with many points of failure and you cannot rely upon it.

## Importing QML Modules

By default, Qt Creator will look in the QML import path of Qt for QML modules.

If you use qmake and your application adds additional import paths that Qt Creator should use, specify them using `QML_IMPORT_PATH` in the `.pro` file of your application: `QML_IMPORT_PATH += path/to/module`.

If you use CMake, add the following command to the CMakeLists.txt file to set the QML import path:

     set(QML_IMPORT_PATH ${CMAKE_SOURCE_DIR}/qml ${CMAKE_BINARY_DIR}/imports CACHE STRING "" FORCE)

The import path affects all the targets built by the CMake project.

UI Files ◦ Developing Widget Based Applications