def create(self, parent, layer):
container = QgsAttributeEditorContainer(self.name)
container.setIsGroupBox(True)
container.setColumnCount(self.columns)
for child in self.children:
container.addChildElement(child, layer)
return container
def create(self, parent, layer):
container = QgsAttributeEditorContainer(self.name, parent)
container.setIsGroupBox(False)
for child in self.children:
container.addChildElement(child.create(container, layer))
return container
def import_in_qgis(gmlas_uri, provider, schema=None):
"""Imports layers from a GMLAS file in QGIS with relations and editor widgets
@param gmlas_uri connection parameters
@param provider name of the QGIS provider that handles gmlas_uri parameters (postgresql or spatialite)
@param schema name of the PostgreSQL schema where tables and metadata tables are
"""
if schema is not None:
schema_s = schema + "."
else:
schema_s = ""
ogr.UseExceptions()
drv = ogr.GetDriverByName(provider)
ds = drv.Open(gmlas_uri)
if ds is None:
raise RuntimeError("Problem opening {}".format(gmlas_uri))
# get list of layers
sql = "select o.*, g.f_geometry_column, g.srid from {}_ogr_layers_metadata o left join geometry_columns g on g.f_table_name = o.layer_name".format(
schema_s)
couches = ds.ExecuteSQL(sql)
layers = {}
for f in couches:
ln = f.GetField("layer_name")
if ln not in layers:
layers[ln] = {
"uid": f.GetField("layer_pkid_name"),
"category": f.GetField("layer_category"),
"xpath": f.GetField("layer_xpath"),
"parent_pkid": f.GetField("layer_parent_pkid_name"),
"srid": f.GetField("srid"),
"geometry_column": f.GetField("f_geometry_column"),
"1_n": [], # 1:N relations
"layer_id": None,
"layer_name": ln,
"layer": None,
"fields": [],
}
else:
# additional geometry columns
g = f.GetField("f_geometry_column")
k = "{} ({})".format(ln, g)
layers[k] = dict(layers[ln])
layers[k]["geometry_column"] = g
# collect fields with xlink:href
href_fields = {}
for ln, layer in layers.items():
layer_name = layer["layer_name"]
for f in ds.ExecuteSQL(
"select field_name, field_xpath from {}_ogr_fields_metadata where layer_name='{}'"
.format(schema_s, layer_name)):
field_name, field_xpath = f.GetField("field_name"), f.GetField(
"field_xpath")
if field_xpath and field_xpath.endswith("@xlink:href"):
if ln not in href_fields:
href_fields[ln] = []
href_fields[ln].append(field_name)
# with unknown srid, don't ask for each layer, set to a default
settings = QgsSettings()
projection_behavior = settings.value("Projections/defaultBehavior")
projection_default = settings.value("Projections/layerDefaultCrs")
settings.setValue("Projections/defaultBehavior", "useGlobal")
settings.setValue("Projections/layerDefaultCrs", "EPSG:4326")
# add layers
crs = QgsCoordinateReferenceSystem("EPSG:4326")
for ln in sorted(layers.keys()):
lyr = layers[ln]
g_column = lyr["geometry_column"] or None
couches = _qgis_layer(
gmlas_uri,
schema,
lyr["layer_name"],
g_column,
provider,
ln,
lyr["xpath"],
lyr["uid"],
)
if not couches.isValid():
raise RuntimeError("Problem loading layer {} with {}".format(
ln, couches.source()))
if g_column is not None:
if lyr["srid"]:
crs = QgsCoordinateReferenceSystem("EPSG:{}".format(
lyr["srid"]))
couches.setCrs(crs)
QgsProject.instance().addMapLayer(couches)
layers[ln]["layer_id"] = couches.id()
layers[ln]["layer"] = couches
# save fields which represent a xlink:href
if ln in href_fields:
couches.setCustomProperty("href_fields", href_fields[ln])
# save gmlas_uri
couches.setCustomProperty("ogr_uri", gmlas_uri)
couches.setCustomProperty("ogr_schema", schema)
# change icon the layer has a custom viewer
xpath = no_ns(couches.customProperty("xpath", ""))
for viewer_cls, _ in get_custom_viewers().values():
tag = no_prefix(viewer_cls.xml_tag())
if tag == xpath:
lg = CustomViewerLegend(viewer_cls.name(), viewer_cls.icon())
couches.setLegend(lg)
# restore settings
settings.setValue("Projections/defaultBehavior", projection_behavior)
settings.setValue("Projections/layerDefaultCrs", projection_default)
# add 1:1 relations
relations_1_1 = []
sql = """
select
layer_name, field_name, field_related_layer, r.child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.parent_element_name = f.field_name
where
field_category in ('PATH_TO_CHILD_ELEMENT_WITH_LINK', 'PATH_TO_CHILD_ELEMENT_NO_LINK')
and field_max_occurs=1
""".format(schema_s)
couches = ds.ExecuteSQL(sql)
if couches is not None:
for f in couches:
rel = QgsRelation()
rel.setId("1_1_" + f.GetField("layer_name") + "_" +
f.GetField("field_name"))
rel.setName("1_1_" + f.GetField("layer_name") + "_" +
f.GetField("field_name"))
# parent layer
rel.setReferencingLayer(
layers[f.GetField("layer_name")]["layer_id"])
# child layer
rel.setReferencedLayer(
layers[f.GetField("field_related_layer")]["layer_id"])
# parent, child
rel.addFieldPair(f.GetField("field_name"),
f.GetField("child_pkid"))
# rel.generateId()
if rel.isValid():
relations_1_1.append(rel)
# add 1:N relations
relations_1_n = []
sql = """
select
layer_name, r.parent_pkid, field_related_layer as child_layer, r.child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category in ('PATH_TO_CHILD_ELEMENT_WITH_LINK', 'PATH_TO_CHILD_ELEMENT_NO_LINK')
and field_max_occurs>1
-- junctions - 1st way
union all
select
layer_name, r.parent_pkid, field_junction_layer as child_layer, 'parent_pkid' as child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category = 'PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE'
-- junctions - 2nd way
union all
select
field_related_layer as layer_name, r.child_pkid, field_junction_layer as child_layer, 'child_pkid' as child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category = 'PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE'
""".format(schema_s)
couches = ds.ExecuteSQL(sql)
if couches is not None:
for f in couches:
parent_layer = f.GetField("layer_name")
child_layer = f.GetField("child_layer")
if parent_layer not in layers or child_layer not in layers:
continue
rel = QgsRelation()
rel.setId("1_n_" + f.GetField("layer_name") + "_" +
f.GetField("child_layer") + "_" +
f.GetField("parent_pkid") + "_" +
f.GetField("child_pkid"))
rel.setName(f.GetField("child_layer"))
# parent layer
rel.setReferencedLayer(layers[parent_layer]["layer_id"])
# child layer
rel.setReferencingLayer(layers[child_layer]["layer_id"])
# parent, child
rel.addFieldPair(f.GetField("child_pkid"),
f.GetField("parent_pkid"))
# rel.addFieldPair(f.GetField('child_pkid'), 'ogc_fid')
if rel.isValid():
relations_1_n.append(rel)
# add relation to layer
layers[f.GetField("layer_name")]["1_n"].append(rel)
for rel in relations_1_1 + relations_1_n:
QgsProject.instance().relationManager().addRelation(rel)
# add "show form" option to 1:1 relations
for rel in relations_1_1:
couches = rel.referencingLayer()
idx = rel.referencingFields()[0]
s = QgsEditorWidgetSetup(
"RelationReference",
{
"AllowNULL": False,
"ReadOnly": True,
"Relation": rel.id(),
"OrderByValue": False,
"MapIdentification": False,
"AllowAddFeatures": False,
"ShowForm": True,
},
)
couches.setEditorWidgetSetup(idx, s)
# setup form for layers
for layer, lyr in layers.items():
couche = lyr["layer"]
fc = couche.editFormConfig()
fc.clearTabs()
fc.setLayout(QgsEditFormConfig.TabLayout)
# Add fields
c = QgsAttributeEditorContainer("Main", fc.invisibleRootContainer())
c.setIsGroupBox(False) # a tab
for idx, f in enumerate(couche.fields()):
c.addChildElement(QgsAttributeEditorField(f.name(), idx, c))
fc.addTab(c)
# Add 1:N relations
c_1_n = QgsAttributeEditorContainer("1:N links",
fc.invisibleRootContainer())
c_1_n.setIsGroupBox(False) # a tab
fc.addTab(c_1_n)
for rel in lyr["1_n"]:
c_1_n.addChildElement(
QgsAttributeEditorRelation(rel.name(), rel, c_1_n))
couche.setEditFormConfig(fc)
install_viewer_on_feature_form(couche)
def import_in_qgis(gmlas_uri, provider, schema = None):
"""Imports layers from a GMLAS file in QGIS with relations and editor widgets
@param gmlas_uri connection parameters
@param provider name of the QGIS provider that handles gmlas_uri parameters (postgresql or spatialite)
@param schema name of the PostgreSQL schema where tables and metadata tables are
"""
if schema is not None:
schema_s = schema + "."
else:
schema_s = ""
ogr.UseExceptions()
drv = ogr.GetDriverByName(provider)
ds = drv.Open(gmlas_uri)
if ds is None:
raise RuntimeError("Problem opening {}".format(gmlas_uri))
# get list of layers
sql = "select o.*, g.f_geometry_column, g.srid from {}_ogr_layers_metadata o left join geometry_columns g on g.f_table_name = o.layer_name".format(schema_s)
l = ds.ExecuteSQL(sql)
layers = {}
for f in l:
ln = f.GetField("layer_name")
if ln not in layers:
layers[ln] = {
'uid': f.GetField("layer_pkid_name"),
'category': f.GetField("layer_category"),
'xpath': f.GetField("layer_xpath"),
'parent_pkid': f.GetField("layer_parent_pkid_name"),
'srid': f.GetField("srid"),
'geometry_column': f.GetField("f_geometry_column"),
'1_n' : [], # 1:N relations
'layer_id': None,
'layer_name' : ln,
'layer': None,
'fields' : []}
else:
# additional geometry columns
g = f.GetField("f_geometry_column")
k = "{} ({})".format(ln, g)
layers[k] = dict(layers[ln])
layers[k]["geometry_column"] = g
# collect fields with xlink:href
href_fields = {}
for ln, layer in layers.items():
layer_name = layer["layer_name"]
for f in ds.ExecuteSQL("select field_name, field_xpath from {}_ogr_fields_metadata where layer_name='{}'".format(schema_s, layer_name)):
field_name, field_xpath = f.GetField("field_name"), f.GetField("field_xpath")
if field_xpath and field_xpath.endswith("@xlink:href"):
if ln not in href_fields:
href_fields[ln] = []
href_fields[ln].append(field_name)
# with unknown srid, don't ask for each layer, set to a default
settings = QgsSettings()
projection_behavior = settings.value("Projections/defaultBehavior")
projection_default = settings.value("Projections/layerDefaultCrs")
settings.setValue("Projections/defaultBehavior", "useGlobal")
settings.setValue("Projections/layerDefaultCrs", "EPSG:4326")
# add layers
crs = QgsCoordinateReferenceSystem("EPSG:4326")
for ln in sorted(layers.keys()):
lyr = layers[ln]
g_column = lyr["geometry_column"] or None
l = _qgis_layer(gmlas_uri, schema, lyr["layer_name"], g_column, provider, ln, lyr["xpath"], lyr["uid"])
if not l.isValid():
raise RuntimeError("Problem loading layer {} with {}".format(ln, l.source()))
if g_column is not None:
if lyr["srid"]:
crs = QgsCoordinateReferenceSystem("EPSG:{}".format(lyr["srid"]))
l.setCrs(crs)
QgsProject.instance().addMapLayer(l)
layers[ln]['layer_id'] = l.id()
layers[ln]['layer'] = l
# save fields which represent a xlink:href
if ln in href_fields:
l.setCustomProperty("href_fields", href_fields[ln])
# save gmlas_uri
l.setCustomProperty("ogr_uri", gmlas_uri)
l.setCustomProperty("ogr_schema", schema)
# change icon the layer has a custom viewer
xpath = no_ns(l.customProperty("xpath", ""))
for viewer_cls, _ in get_custom_viewers().values():
tag = no_prefix(viewer_cls.xml_tag())
if tag == xpath:
lg = CustomViewerLegend(viewer_cls.name(), viewer_cls.icon())
l.setLegend(lg)
# restore settings
settings.setValue("Projections/defaultBehavior", projection_behavior)
settings.setValue("Projections/layerDefaultCrs", projection_default)
# add 1:1 relations
relations_1_1 = []
sql = """
select
layer_name, field_name, field_related_layer, r.child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.parent_element_name = f.field_name
where
field_category in ('PATH_TO_CHILD_ELEMENT_WITH_LINK', 'PATH_TO_CHILD_ELEMENT_NO_LINK')
and field_max_occurs=1
""".format(schema_s)
l = ds.ExecuteSQL(sql)
if l is not None:
for f in l:
rel = QgsRelation()
rel.setId('1_1_' + f.GetField('layer_name') + '_' + f.GetField('field_name'))
rel.setName('1_1_' + f.GetField('layer_name') + '_' + f.GetField('field_name'))
# parent layer
rel.setReferencingLayer(layers[f.GetField('layer_name')]['layer_id'])
# child layer
rel.setReferencedLayer(layers[f.GetField('field_related_layer')]['layer_id'])
# parent, child
rel.addFieldPair(f.GetField('field_name'), f.GetField('child_pkid'))
#rel.generateId()
if rel.isValid():
relations_1_1.append(rel)
# add 1:N relations
relations_1_n = []
sql = """
select
layer_name, r.parent_pkid, field_related_layer as child_layer, r.child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category in ('PATH_TO_CHILD_ELEMENT_WITH_LINK', 'PATH_TO_CHILD_ELEMENT_NO_LINK')
and field_max_occurs>1
-- junctions - 1st way
union all
select
layer_name, r.parent_pkid, field_junction_layer as child_layer, 'parent_pkid' as child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category = 'PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE'
-- junctions - 2nd way
union all
select
field_related_layer as layer_name, r.child_pkid, field_junction_layer as child_layer, 'child_pkid' as child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category = 'PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE'
""".format(schema_s)
l = ds.ExecuteSQL(sql)
if l is not None:
for f in l:
parent_layer = f.GetField("layer_name")
child_layer = f.GetField("child_layer")
if parent_layer not in layers or child_layer not in layers:
continue
rel = QgsRelation()
rel.setId('1_n_' + f.GetField('layer_name') + '_' + f.GetField('child_layer') + '_' + f.GetField('parent_pkid') + '_' + f.GetField('child_pkid'))
rel.setName(f.GetField('child_layer'))
# parent layer
rel.setReferencedLayer(layers[parent_layer]['layer_id'])
# child layer
rel.setReferencingLayer(layers[child_layer]['layer_id'])
# parent, child
rel.addFieldPair(f.GetField('child_pkid'), f.GetField('parent_pkid'))
#rel.addFieldPair(f.GetField('child_pkid'), 'ogc_fid')
if rel.isValid():
relations_1_n.append(rel)
# add relation to layer
layers[f.GetField('layer_name')]['1_n'].append(rel)
for rel in relations_1_1 + relations_1_n:
QgsProject.instance().relationManager().addRelation(rel)
# add "show form" option to 1:1 relations
for rel in relations_1_1:
l = rel.referencingLayer()
idx = rel.referencingFields()[0]
s = QgsEditorWidgetSetup("RelationReference", {'AllowNULL': False,
'ReadOnly': True,
'Relation': rel.id(),
'OrderByValue': False,
'MapIdentification': False,
'AllowAddFeatures': False,
'ShowForm': True})
l.setEditorWidgetSetup(idx, s)
# setup form for layers
for layer, lyr in layers.items():
l = lyr['layer']
fc = l.editFormConfig()
fc.clearTabs()
fc.setLayout(QgsEditFormConfig.TabLayout)
# Add fields
c = QgsAttributeEditorContainer("Main", fc.invisibleRootContainer())
c.setIsGroupBox(False) # a tab
for idx, f in enumerate(l.fields()):
c.addChildElement(QgsAttributeEditorField(f.name(), idx, c))
fc.addTab(c)
# Add 1:N relations
c_1_n = QgsAttributeEditorContainer("1:N links", fc.invisibleRootContainer())
c_1_n.setIsGroupBox(False) # a tab
fc.addTab(c_1_n)
for rel in lyr['1_n']:
c_1_n.addChildElement(QgsAttributeEditorRelation(rel.name(), rel, c_1_n))
l.setEditFormConfig(fc)
install_viewer_on_feature_form(l)
def import_in_qgis(gmlas_uri, provider, schema=None):
"""Imports layers from a GMLAS file in QGIS with relations and editor widgets
@param gmlas_uri connection parameters
@param provider name of the QGIS provider that handles gmlas_uri parameters (postgresql or spatialite)
@param schema name of the PostgreSQL schema where tables and metadata tables are
"""
if schema is not None:
schema_s = schema + "."
else:
schema_s = ""
ogr.UseExceptions()
drv = ogr.GetDriverByName(provider)
ds = drv.Open(gmlas_uri)
if ds is None:
raise RuntimeError("Problem opening {}".format(gmlas_uri))
# get list of layers
sql = "select o.*, g.f_geometry_column, g.srid from {}_ogr_layers_metadata o left join geometry_columns g on g.f_table_name = o.layer_name".format(
schema_s)
l = ds.ExecuteSQL(sql)
layers = {}
for f in l:
ln = f.GetField("layer_name")
if ln not in layers:
layers[ln] = {
'uid': f.GetField("layer_pkid_name"),
'category': f.GetField("layer_category"),
'xpath': f.GetField("layer_xpath"),
'parent_pkid': f.GetField("layer_parent_pkid_name"),
'srid': f.GetField("srid"),
'geometry_column': f.GetField("f_geometry_column"),
'1_n': [], # 1:N relations
'layer_id': None,
'layer_name': ln,
'layer': None,
'fields': []
}
else:
# additional geometry columns
g = f.GetField("f_geometry_column")
k = "{} ({})".format(ln, g)
layers[k] = dict(layers[ln])
layers[k]["geometry_column"] = g
crs = QgsCoordinateReferenceSystem("EPSG:4326")
for ln in sorted(layers.keys()):
lyr = layers[ln]
g_column = lyr["geometry_column"] or None
l = _qgis_layer(gmlas_uri,
schema,
lyr["layer_name"],
g_column,
provider,
qgis_layer_name=ln)
if not l.isValid():
raise RuntimeError("Problem loading layer {} with {}".format(
ln, l.source()))
if lyr["srid"]:
crs = QgsCoordinateReferenceSystem("EPSG:{}".format(lyr["srid"]))
l.setCrs(crs)
QgsProject.instance().addMapLayer(l)
layers[ln]['layer_id'] = l.id()
layers[ln]['layer'] = l
# add 1:1 relations
relations_1_1 = []
sql = """
select
layer_name, field_name, field_related_layer, r.child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.parent_element_name = f.field_name
where
field_category in ('PATH_TO_CHILD_ELEMENT_WITH_LINK', 'PATH_TO_CHILD_ELEMENT_NO_LINK')
and field_max_occurs=1
""".format(schema_s)
l = ds.ExecuteSQL(sql)
if l is not None:
for f in l:
rel = QgsRelation()
rel.setId('1_1_' + f.GetField('layer_name') + '_' +
f.GetField('field_name'))
rel.setName('1_1_' + f.GetField('layer_name') + '_' +
f.GetField('field_name'))
# parent layer
rel.setReferencingLayer(
layers[f.GetField('layer_name')]['layer_id'])
# child layer
rel.setReferencedLayer(
layers[f.GetField('field_related_layer')]['layer_id'])
# parent, child
rel.addFieldPair(f.GetField('field_name'),
f.GetField('child_pkid'))
#rel.generateId()
if rel.isValid():
relations_1_1.append(rel)
# add 1:N relations
relations_1_n = []
sql = """
select
layer_name, r.parent_pkid, field_related_layer as child_layer, r.child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category in ('PATH_TO_CHILD_ELEMENT_WITH_LINK', 'PATH_TO_CHILD_ELEMENT_NO_LINK')
and field_max_occurs>1
-- junctions - 1st way
union all
select
layer_name, r.parent_pkid, field_junction_layer as child_layer, 'parent_pkid' as child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category = 'PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE'
-- junctions - 2nd way
union all
select
field_related_layer as layer_name, r.child_pkid, field_junction_layer as child_layer, 'child_pkid' as child_pkid
from
{0}_ogr_fields_metadata f
join {0}_ogr_layer_relationships r
on r.parent_layer = f.layer_name
and r.child_layer = f.field_related_layer
where
field_category = 'PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE'
""".format(schema_s)
l = ds.ExecuteSQL(sql)
if l is not None:
for f in l:
rel = QgsRelation()
rel.setId('1_n_' + f.GetField('layer_name') + '_' +
f.GetField('child_layer') + '_' +
f.GetField('parent_pkid') + '_' +
f.GetField('child_pkid'))
rel.setName(f.GetField('child_layer'))
# parent layer
rel.setReferencedLayer(
layers[f.GetField('layer_name')]['layer_id'])
# child layer
rel.setReferencingLayer(
layers[f.GetField('child_layer')]['layer_id'])
# parent, child
rel.addFieldPair(f.GetField('child_pkid'),
f.GetField('parent_pkid'))
#rel.addFieldPair(f.GetField('child_pkid'), 'ogc_fid')
if rel.isValid():
relations_1_n.append(rel)
# add relation to layer
layers[f.GetField('layer_name')]['1_n'].append(rel)
QgsProject.instance().relationManager().setRelations(relations_1_1 +
relations_1_n)
# add "show form" option to 1:1 relations
for rel in relations_1_1:
l = rel.referencingLayer()
idx = rel.referencingFields()[0]
s = QgsEditorWidgetSetup(
"RelationReference", {
'AllowNULL': False,
'ReadOnly': True,
'Relation': rel.id(),
'OrderByValue': False,
'MapIdentification': False,
'AllowAddFeatures': False,
'ShowForm': True
})
l.setEditorWidgetSetup(idx, s)
# setup form for layers
for layer, lyr in layers.items():
l = lyr['layer']
fc = l.editFormConfig()
fc.clearTabs()
fc.setLayout(QgsEditFormConfig.TabLayout)
# Add fields
c = QgsAttributeEditorContainer("Main", fc.invisibleRootContainer())
c.setIsGroupBox(False) # a tab
for idx, f in enumerate(l.fields()):
c.addChildElement(QgsAttributeEditorField(f.name(), idx, c))
fc.addTab(c)
# Add 1:N relations
c_1_n = QgsAttributeEditorContainer("1:N links",
fc.invisibleRootContainer())
c_1_n.setIsGroupBox(False) # a tab
fc.addTab(c_1_n)
for rel in lyr['1_n']:
c_1_n.addChildElement(
QgsAttributeEditorRelation(rel.name(), rel, c_1_n))
l.setEditFormConfig(fc)