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qt_query_qml_module

Retrieve information about a QML module.

The command is defined in the Qml component of the Qt6 package, which can be loaded like so:

 find_package(Qt6 REQUIRED COMPONENTS Qml)

This command was introduced in Qt 6.3.

Synopsis

 qt_query_qml_module(
     target
     [URI uri_var]
     [VERSION version_var]
     [PLUGIN_TARGET plugin_target_var]
     [TARGET_PATH target_path_var]
     [MODULE_RESOURCE_PATH module_resource_path_var]
     [QMLDIR qmldir_var]
     [TYPEINFO typeinfo_var]
     [QML_FILES qml_files_var]
     [QML_FILES_DEPLOY_PATHS qml_files_deploy_paths_var]
     [QML_FILES_PREFIX_OVERRIDES qml_files_prefix_overrides_var]
     [RESOURCES resources_var]
     [RESOURCES_DEPLOY_PATHS resources_deploy_paths_var]
     [RESOURCES_PREFIX_OVERRIDES resources_prefix_overrides_var]
 )

If versionless commands are disabled, use qt6_query_qml_module() instead. It supports the same set of arguments as this command.

Description

This command is used to obtain information about a QML module target. That target must have previously been created by or passed to an earlier call to qt_add_qml_module(). The target cannot be an imported target.

The information provided by this command enables the caller to deploy all parts of a single QML module. The project should install the target and the associated plugin target (if the module has one and it is separate from the backing target) using the standard install(TARGETS) command. Everything else can be deployed with install(FILES).

Arguments

Each of the optional arguments specifies the name of a variable in which to store the corresponding QML module property.

URI and VERSION provide the module's uri and version respectively.

PLUGIN_TARGET can be used to obtain the name of the plugin target for the QML module. Not all QML modules have a plugin, so the value returned for this option could be an empty string. If the QML module has no separate backing target, then target will be the same as the plugin target.

TARGET_PATH is the URI with dots (.) replaced by forward slashes (/). It represents the path below the base QML module installation directory where this QML module's qmldir file (and possibly others) should be deployed. The QML module installation directory serves as a QML import path where the QML engine will look for QML modules. The default base QML module installation directory used by qt_generate_deploy_qml_app_script() is qml. A project using a deployment script can use QT_DEPLOY_QML_DIR rather than hard-coding this location (also see QT_DEPLOY_PREFIX).

MODULE_RESOURCE_PATH provides the resource path under which the QML module's compiled-in files can be found. It is formed from qt_add_qml_module()'s RESOURCE_PREFIX concatenated with the module's TARGET_PATH. The queried value should not be used for deployment, but may be helpful in matching up resource paths with file system locations, if needed.

QMLDIR provides the path to the qmldir file. When deploying the QML module, this file should be copied to the target path. In a deployment script, this location can be obtained using ${QT_DEPLOY_PREFIX}/${QT_DEPLOY_QML_DIR}.

TYPEINFO provides the path to the module's typeinfo file, if it has one. It will be an empty string if the module has no typeinfo file. The typeinfo file should be deployed to the same path as the qmldir file.

QML_FILES provides a list of all files added to the QML module through one of the following methods:

All files will be recorded with absolute paths.

QML_FILES_DEPLOY_PATHS provides a list with exactly the same number of elements as QML_FILES. Each element of the QML_FILES_DEPLOY_PATHS list is the path below the target path where the corresponding element of QML_FILES should be deployed. The paths in QML_FILES_DEPLOY_PATHS include the file name, since this could be different to the file name in QML_FILES due to the use of resource aliases (see QT_RESOURCE_ALIAS).

Entries in QML_FILES_DEPLOY_PATHS can also be an empty string. Any file added using qt_target_qml_sources() with a custom PREFIX will have no deploy path, since using a custom prefix typically means the file sits outside of the QML module's target path.

QML_FILES_PREFIX_OVERRIDES provides another list with exactly the same number of elements as QML_FILES. Where a file has been added with a custom prefix as described in the preceding paragraph, its corresponding entry in the QML_FILES_PREFIX_OVERRIDES list will contain the custom prefix used. For all other files, their list entries will be an empty string.

Note: As a special case, if there is only one file in the QML_FILES list, then QML_FILES_DEPLOY_PATHS or QML_FILES_PREFIX_OVERRIDES may be an empty string depending on whether that file has a custom prefix. This is because CMake's way of representing lists and strings means that it is impossible to distinguish between an empty string and a list with a single empty element.

The RESOURCES, RESOURCES_DEPLOY_PATHS, and RESOURCES_PREFIX_OVERRIDES options are analogous to those for QML_FILES discussed above. RESOURCES provides a list of all files added to the QML module as RESOURCES arguments to either qt_add_qml_module() or qt_target_qml_sources(). All paths will be absolute. The meaning and usage of RESOURCES_DEPLOY_PATHS and RESOURCES_PREFIX_OVERRIDES follows the same patterns as QML_FILES_DEPLOY_PATHS and QML_FILES_PREFIX_OVERRIDES respectively.

Example

 cmake_minimum_required(VERSION 3.16...3.22)
 project(MyThings)

 find_package(Qt6 6.3 REQUIRED COMPONENTS Core Qml)

 set(module_name "MyThings")
 qt_add_qml_module(${module_name}
     URI My.Things
     VERSION 1.3
     RESOURCE_PREFIX org.mycompany/imports
     QML_FILES
         First.qml
         Second.qml
     RESOURCES
         Third.txt
 )

 qt_query_qml_module(${module_name}
     URI module_uri
     VERSION module_version
     PLUGIN_TARGET module_plugin_target
     TARGET_PATH module_target_path
     QMLDIR module_qmldir
     TYPEINFO module_typeinfo
     QML_FILES module_qml_files
     QML_FILES_DEPLOY_PATHS qml_files_deploy_paths
     RESOURCES module_resources
     RESOURCES_DEPLOY_PATHS resources_deploy_paths
 )

 message("My QML module URI is: ${module_uri}")
 message("My QML module version is: ${module_version}")

 # Install the QML module backing library
 set(staging_prefix "staging")
 install(TARGETS ${module_name}
     ARCHIVE DESTINATION "${staging_prefix}/${CMAKE_INSTALL_LIBDIR}"
     LIBRARY DESTINATION "${staging_prefix}/${CMAKE_INSTALL_LIBDIR}"
     RUNTIME DESTINATION "${staging_prefix}/${CMAKE_INSTALL_BINDIR}"
 )
 set(module_dir "${staging_prefix}/qml/${module_target_path}")

 # Install the QML module runtime loadable plugin
 install(TARGETS "${module_plugin_target}"
     LIBRARY DESTINATION "${module_dir}"
     RUNTIME DESTINATION "${module_dir}"
 )

 # Install the QML module meta information.
 install(FILES "${module_qmldir}"   DESTINATION "${module_dir}")
 install(FILES "${module_typeinfo}" DESTINATION "${module_dir}")

 # Install QML files, possibly renamed.
 list(LENGTH module_qml_files num_files)
 math(EXPR last_index "${num_files} - 1")
 foreach(i RANGE 0 ${last_index})
     list(GET module_qml_files       ${i} src_file)
     list(GET qml_files_deploy_paths ${i} deploy_path)
     get_filename_component(dst_name "${deploy_path}" NAME)
     get_filename_component(dest_dir "${deploy_path}" DIRECTORY)
     install(FILES "${src_file}" DESTINATION "${module_dir}/${dest_dir}" RENAME "${dst_name}")
 endforeach()

 # Install resources, possibly renamed.
 list(LENGTH module_resources num_files)
 math(EXPR last_index "${num_files} - 1")
 foreach(i RANGE 0 ${last_index})
     list(GET module_resources       ${i} src_file)
     list(GET resources_deploy_paths ${i} deploy_path)
     get_filename_component(dst_name "${deploy_path}" NAME)
     get_filename_component(dest_dir "${deploy_path}" DIRECTORY)
     install(FILES "${src_file}" DESTINATION "${module_dir}/${dest_dir}" RENAME "${dst_name}")
 endforeach()

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