QgsLayerDefinition class

The QgsLayerDefinition class holds generic methods for loading/exporting QLR files.

Reference
- Public types
- Public static functions

QLR files are an export of the layer xml including the style and datasource location. There is no link to the QLR file once loaded. Consider the QLR file a mini project file for layers and styles. QLR files also store the layer tree info for the exported layers, including group information.

Public types

class DependencySorter: Class used to work with layer dependencies stored in a XML project or layer definition file.

Public static functions

static auto exportLayerDefinition(QString path, const QList<QgsLayerTreeNode*>& selectedTreeNodes, QString& errorMessage) -> bool: Export the selected layer tree nodes to a QLR file.
static auto exportLayerDefinition(QDomDocument doc, const QList<QgsLayerTreeNode*>& selectedTreeNodes, QString& errorMessage, const QgsReadWriteContext& context) -> bool: Export the selected layer tree nodes to a QLR-XML document.
static auto exportLayerDefinitionLayers(const QList<QgsMapLayer*>& layers, const QgsReadWriteContext& context) -> QDomDocument: Returns the given layer as a layer definition document Layer definitions store the data source as well as styling and custom properties.
static auto loadLayerDefinition(const QString& path, QgsProject* project, QgsLayerTreeGroup* rootGroup, QString& errorMessage) -> bool: Loads the QLR at path into QGIS. New layers are added to given project into layer tree specified by rootGroup.
static auto loadLayerDefinition(QDomDocument doc, QgsProject* project, QgsLayerTreeGroup* rootGroup, QString& errorMessage, QgsReadWriteContext& context) -> bool: Loads the QLR from the XML document. New layers are added to given project into layer tree specified by rootGroup.
static auto loadLayerDefinitionLayers(QDomDocument& document, QgsReadWriteContext& context) -> QList<QgsMapLayer*>: Creates new layers from a layer definition document.
static auto loadLayerDefinitionLayers(const QString& qlrfile) -> QList<QgsMapLayer*>: Creates new layers from a layer definition file (.QLR) This is a low-level routine that does not resolve layer ID conflicts, dependencies and joins.

Function documentation

static QDomDocument QgsLayerDefinition::exportLayerDefinitionLayers(const QList<QgsMapLayer*>& layers, const QgsReadWriteContext& context)

Returns the given layer as a layer definition document Layer definitions store the data source as well as styling and custom properties.

Layer definitions can be used to load a layer and styling all from a single file.

This is a low-level routine that does not write layer tree.

static QList<QgsMapLayer*> QgsLayerDefinition::loadLayerDefinitionLayers(QDomDocument& document, QgsReadWriteContext& context)

Creates new layers from a layer definition document.

This is a low-level routine that does not resolve layer ID conflicts, dependencies and joins

static QList<QgsMapLayer*> QgsLayerDefinition::loadLayerDefinitionLayers(const QString& qlrfile)

Creates new layers from a layer definition file (.QLR) This is a low-level routine that does not resolve layer ID conflicts, dependencies and joins.