Loading a style (.qml) via PyQGIS

Question

I want to load a (.qml) style file to a specific layer, I tried this:

layer = QgsProject.instance().mapLayersByName(layer_name)
if layer.wkbType() == QGis.WKBLineString:
 layer.loadNamedStyle('styles/lines.qml')
layer.triggerRepaint()

Also, I tried this:

layer = QgsProject.instance().mapLayersByName(layer_name)
if layer.geometryType() == QgsWkbTypes.LineGeometry:
 layer.loadNamedStyle('styles/lines.qml')
layer.triggerRepaint()

But I get this error:

if layer.wkbType() == QGis.WKBLineString:
# AttributeError: 'list' object has no attribute 'wkbType'

• ThomasG77: FYI QGis.WKBLineString was in QGIS old series 1.x and 2.x. layer.wkbType() == QGis.WKBLineString: should be now layer.wkbType() == QgsWkbTypes.LineString. See doc at qgis.org/api/… @ben-w has already answered for your overall issue

Answer 1

The method mapLayersByName() returns a list. To return a layer object you need to index the list to access its first element (assuming there is only one layer by that name in your project) e.g.

layer = QgsProject.instance().mapLayersByName(layer_name)[0]
if layer.geometryType() == 1:#Line geometry
 layer.loadNamedStyle('path\\to\\style_file.qml')

• etrimaille: Correct about the list. I would really keep if layer.geometryType() == QgsWkbTypes.LineGeometry:. It makes the code more readable instead of having to keep an index.