def checkJoinExists(layername, fieldname, targetlayer, targetfield):
"""
Returns True if vector layer has a join with a
target layer using the specified field and target field
:param layername: vector layer name
:param fieldname: join field name
:param targetlayer: target vector layer name
:param targetfield: target join field name
:return: Boolean
"""
layer = layerFromName(layername)
tlayer = layerFromName(targetlayer)
# check if layers exist
if layer is None or tlayer is None:
return False
# check if join fields exist
if fieldname not in [f.name() for f in layer.pendingFields()] or \
targetfield not in [f.name() for f in tlayer.pendingFields()]:
return False
join_settings = (tlayer.id(), unicode(targetfield), unicode(fieldname))
for j in layer.vectorJoins():
if (j.joinLayerId, j.joinFieldName,
j.targetFieldName) == join_settings:
return True
return False
def checkFieldValue(layername, field, value):
"""
Return True if all features have a certain value for a
particular field. If the layer has selected features, only those will be
taken in account
:param layername: Layer's name as in the layers panel
:param field: Field name
:param value: value to confirm
:return: Boolean
"""
layer = layerFromName(layername)
if layer is None:
return False
if layer.selectedFeatureCount():
features = layer.selectedFeatures()
else:
features = layer.getFeatures()
for feature in features:
if feature.attribute(field) != value:
return False
return True
def selectByRectangle(layername, xmin, ymin, xmax, ymax):
"""
Select features in rectangle
:param layername: Layer's name as in the layers panel
:return: None
"""
layer = layerFromName(layername)
if layer is not None and layer.type() == QgsMapLayer.VectorLayer:
layer.selectByRect(QgsRectangle(xmin, ymin, xmax, ymax))
def isLayerSaved(layername):
"""
Returns True if no changes were made in the layer after the last save
:param layername: Layer name as in the layers panel
:return: Boolean
"""
layer = layerFromName(layername)
return layer is not None and layer.type() == QgsMapLayer.VectorLayer and \
not layer.isModified()
def checkLayerInProject(layername):
layer = layerFromName(layername)
return layer is not None
def checkEdited(layername):
layer = layerFromName(layername)
if layer:
return len(hasLocalChanges(layer)) > 0
else:
return False
def isLayerEditable(*args):
"""Returns True if layer with given name is in editable mode.
NOTE: layer should be of the vector type and be loaded into project.
"""
layer = layerFromName(args[0])
return layer is not None and layer.isEditable()