Class: QgsLayerMetadata¶

A structured metadata store for a map layer.

QgsLayerMetadata handles storage and management of the metadata for a QgsMapLayer. This class is an internal QGIS format with a common metadata structure, which allows for code to access the metadata properties for layers in a uniform way.

The metadata store is designed to be compatible with the Dublin Core metadata specifications, and will be expanded to allow compatibility with ISO specifications in future releases. However, the QGIS internal schema does not represent a superset of all existing metadata schemas and accordingly conversion from specific metadata formats to QgsLayerMetadata may result in a loss of information.

This class is designed to follow the specifications detailed in the schema definition available at resources/qgis-resource-metadata.xsd within the QGIS source code.

Metadata can be validated through the use of QgsLayerMetadataValidator subclasses. E.g. validating against the native QGIS metadata schema can be performed using QgsNativeMetadataValidator.

Class Hierarchy¶

Base classes¶

QgsAbstractMetadataBase

An abstract base class for metadata stores.

Subclasses¶

QgsLayerMetadataProviderResult

Result record of layer metadata provider search.

Methods

`addConstraint`	Adds an individual constraint to the existing constraints.
`constraints`	Returns a list of constraints associated with using the resource.
`contains`	Returns `True` if the metadata identifier, title, abstract, keywords or categories contain searchString using case-insensitive search.
`crs`	Returns the coordinate reference system described by the layer's metadata.
`encoding`	Returns the character encoding of the data in the resource.
`extent`	Returns the spatial and temporal extents associated with the resource.
`fees`	Returns any fees associated with using the resource.
`licenses`	Returns a list of licenses associated with the resource (examples: http://opendefinition.org/licenses/).
`matches`	Returns `True` if the metadata identifier, title, abstract, keywords or categories matches any regular expression from searchReList.
`readFromLayer`	Reads the metadata state from a layer's custom properties (see `QgsMapLayer.customProperty()` ).
`rights`	Returns a list of attribution or copyright strings associated with the resource.
`saveToLayer`	Saves the metadata to a layer's custom properties (see `QgsMapLayer.setCustomProperty()` ).
`setConstraints`	Sets the list of constraints associated with using the resource.
`setCrs`	Sets the coordinate reference system for the layer's metadata.
`setEncoding`	Sets the character encoding of the data in the resource.
`setExtent`	Sets the spatial and temporal extents associated with the resource.
`setFees`	Sets the fees associated with using the resource.
`setLicenses`	Sets a list of licenses associated with the resource.
`setRights`	Sets a list of rights (attribution or copyright strings) associated with the resource.

class qgis.core.QgsLayerMetadata[source]¶

Bases: QgsAbstractMetadataBase

class Constraint¶

Bases: object

Metadata constraint structure.

constraint: str¶: Free-form constraint string.

class Extent¶

Bases: object

Metadata extent structure.

setSpatialExtents(self, extents: Iterable[QgsLayerMetadata.SpatialExtent])¶

Sets the spatial extents of the resource.

See also

spatialExtents()

Parameters:: extents (Iterable[QgsLayerMetadata.SpatialExtent])

setTemporalExtents(self, extents: Iterable[QgsDateTimeRange])¶

Sets the temporal extents of the resource.

See also

temporalExtents()

Parameters:: extents (Iterable[QgsDateTimeRange])

spatialExtents(self) → List[QgsLayerMetadata.SpatialExtent]¶

Spatial extents of the resource.

See also

setSpatialExtents()

Return type:: List[QgsLayerMetadata.SpatialExtent]

temporalExtents(self) → List[QgsDateTimeRange]¶

Temporal extents of the resource. Use QgsDateTimeRange.isInstant() to determine whether the temporal extent is a range or a single point in time. If QgsDateTimeRange.isInfinite() returns True then the temporal extent is considered to be indeterminate and continuous.

See also

setTemporalExtents()

Return type:: List[QgsDateTimeRange]

class SpatialExtent¶

Bases: object

Metadata spatial extent structure.

bounds: QgsBox3D¶

Geospatial extent of the resource. X and Y coordinates are in the CRS defined by the metadata (see extentCrs).

While the spatial extent can include a Z dimension, this is not compulsory.

See also

extentCrs()

extentCrs: QgsCoordinateReferenceSystem¶: Coordinate reference system for spatial extent. The CRS should match the CRS defined in the QgsLayerMetadata CRS property.

See also

QgsLayerMetadata.crs()

See also

spatial()

addConstraint(self, constraint: QgsLayerMetadata.Constraint)[source]¶

Adds an individual constraint to the existing constraints.

See also

constraints()

See also

setConstraints()

Parameters:: constraint (QgsLayerMetadata.Constraint)

constraints(self) → List[QgsLayerMetadata.Constraint][source]¶

Returns a list of constraints associated with using the resource.

See also

setConstraints()

Return type:: List[QgsLayerMetadata.Constraint]

contains(self, searchString: str | None) → bool[source]¶

Returns True if the metadata identifier, title, abstract, keywords or categories contain searchString using case-insensitive search.

If searchString is empty this method returns False.

Added in version 3.28.

Parameters:: searchString (Optional[str])
Return type:: bool

crs(self) → QgsCoordinateReferenceSystem[source]¶

Returns the coordinate reference system described by the layer’s metadata.

Note that this has no link to QgsMapLayer.crs(). While in most cases these two systems are likely to be identical, it is possible to have a layer with a different CRS described by it’s accompanying metadata versus the CRS which is actually used to display and manipulate the layer within QGIS. This may be the case when a layer has an incorrect CRS within its metadata and a user has manually overridden the layer’s CRS within QGIS.

The CRS described here should either match the CRS from the layer QgsMapLayer.crs() or the CRS from the data provider.

This property should also match the CRS property used in the spatial extent.

See also

setCrs()

Return type:: QgsCoordinateReferenceSystem

encoding(self) → str[source]¶

Returns the character encoding of the data in the resource. An empty string will be returned if no encoding is set.

See also

setEncoding()

Return type:: str

extent(self) → QgsLayerMetadata.Extent¶

Returns the spatial and temporal extents associated with the resource.

See also

setExtent()

Return type:: QgsLayerMetadata.Extent

fees(self) → str[source]¶

Returns any fees associated with using the resource. An empty string will be returned if no fees are set.

See also

setFees()

Return type:: str

licenses(self) → List[str][source]¶

Returns a list of licenses associated with the resource (examples: http://opendefinition.org/licenses/).

See also

setLicenses()

Return type:: List[str]

matches(self, searchReList: Iterable[QRegularExpression]) → bool[source]¶

Returns True if the metadata identifier, title, abstract, keywords or categories matches any regular expression from searchReList.

Added in version 3.28.

Parameters:: searchReList (Iterable[QRegularExpression])
Return type:: bool

readFromLayer(self, layer: QgsMapLayer | None)[source]¶

Reads the metadata state from a layer’s custom properties (see QgsMapLayer.customProperty() ).

See also

saveToLayer()

Parameters:: layer (Optional[QgsMapLayer])

rights(self) → List[str][source]¶

Returns a list of attribution or copyright strings associated with the resource.

See also

setRights()

Return type:: List[str]

saveToLayer(self, layer: QgsMapLayer | None)[source]¶

Saves the metadata to a layer’s custom properties (see QgsMapLayer.setCustomProperty() ).

See also

readFromLayer()

Parameters:: layer (Optional[QgsMapLayer])

setConstraints(self, constraints: Iterable[QgsLayerMetadata.Constraint])[source]¶

Sets the list of constraints associated with using the resource.

See also

constraints()

Parameters:: constraints (Iterable[QgsLayerMetadata.Constraint])

setCrs(self, crs: QgsCoordinateReferenceSystem)[source]¶

Sets the coordinate reference system for the layer’s metadata.

Note that this has no link to QgsMapLayer.setCrs(). Setting the layer’s CRS via QgsMapLayer.setCrs() does not affect the layer’s metadata CRS, and changing the CRS from the metadata will not change the layer’s CRS or how it is projected within QGIS.

While ideally these two systems are likely to be identical, it is possible to have a layer with a different CRS described by it’s accompanying metadata versus the CRS which is actually used to display and manipulate the layer within QGIS. This may be the case when a layer has an incorrect CRS within its metadata and a user has manually overridden the layer’s CRS within QGIS.

The CRS described here should either match the CRS from the layer QgsMapLayer.crs() or the CRS from the data provider.

This property should also match the CRS property used in the spatial extent.

See also

crs()