[1.7.x] Added Spatialite support to the new migration framework

Refs #22451.
Backport of 2ffa6ca73a from master.

2 files changed, 102 insertions, 0 deletions

diff --git a/django/contrib/gis/db/backends/spatialite/base.py b/django/contrib/gis/db/backends/spatialite/base.py
index 2efc274106..69d6d8e2df 100644
--- a/django/contrib/gis/db/backends/spatialite/base.py
+++ b/django/contrib/gis/db/backends/spatialite/base.py
@@ -9,6 +9,7 @@ from django.contrib.gis.db.backends.spatialite.client import SpatiaLiteClient
 from django.contrib.gis.db.backends.spatialite.creation import SpatiaLiteCreation
 from django.contrib.gis.db.backends.spatialite.introspection import SpatiaLiteIntrospection
 from django.contrib.gis.db.backends.spatialite.operations import SpatiaLiteOperations
+from django.contrib.gis.db.backends.spatialite.schema import SpatialiteSchemaEditor
 from django.utils import six
 
 
@@ -37,6 +38,10 @@ class DatabaseWrapper(SQLiteDatabaseWrapper):
         self.creation = SpatiaLiteCreation(self)
         self.introspection = SpatiaLiteIntrospection(self)
 
+    def schema_editor(self, *args, **kwargs):
+        "Returns a new instance of this backend's SchemaEditor"
+        return SpatialiteSchemaEditor(self, *args, **kwargs)
+
     def get_new_connection(self, conn_params):
         conn = super(DatabaseWrapper, self).get_new_connection(conn_params)
         # Enabling extension loading on the SQLite connection.
diff --git a/django/contrib/gis/db/backends/spatialite/schema.py b/django/contrib/gis/db/backends/spatialite/schema.py
new file mode 100644
index 0000000000..b1283c39af
--- /dev/null
+++ b/django/contrib/gis/db/backends/spatialite/schema.py
@@ -0,0 +1,97 @@
+from django.db.backends.sqlite3.schema import DatabaseSchemaEditor
+
+
+class SpatialiteSchemaEditor(DatabaseSchemaEditor):
+    sql_add_geometry_column = "SELECT AddGeometryColumn(%(table)s, %(column)s, %(srid)s, %(geom_type)s, %(dim)s, %(null)s)"
+    sql_add_spatial_index = "SELECT CreateSpatialIndex(%(table)s, %(column)s)"
+    sql_drop_spatial_index = "DROP TABLE idx_%(table)s_%(column)s"
+    sql_remove_geometry_metadata = "SELECT DiscardGeometryColumn(%(table)s, %(column)s)"
+    sql_update_geometry_columns = "UPDATE geometry_columns SET f_table_name = %(new_table)s WHERE f_table_name = %(old_table)s"
+
+    def __init__(self, *args, **kwargs):
+        super(SpatialiteSchemaEditor, self).__init__(*args, **kwargs)
+        self.geometry_sql = []
+
+    def geo_quote_name(self, name):
+        return self.connection.ops.geo_quote_name(name)
+
+    def column_sql(self, model, field, include_default=False):
+        from django.contrib.gis.db.models.fields import GeometryField
+        if not isinstance(field, GeometryField):
+            return super(SpatialiteSchemaEditor, self).column_sql(model, field, include_default)
+
+        # Geometry columns are created by the `AddGeometryColumn` function
+        self.geometry_sql.append(
+            self.sql_add_geometry_column % {
+                "table": self.geo_quote_name(model._meta.db_table),
+                "column": self.geo_quote_name(field.column),
+                "srid": field.srid,
+                "geom_type": self.geo_quote_name(field.geom_type),
+                "dim": field.dim,
+                "null": int(not field.null),
+            }
+        )
+
+        if field.spatial_index:
+            self.geometry_sql.append(
+                self.sql_add_spatial_index % {
+                    "table": self.quote_name(model._meta.db_table),
+                    "column": self.quote_name(field.column),
+                }
+            )
+        return None, None
+
+    def remove_geometry_metadata(self, model, field):
+        self.execute(
+            self.sql_remove_geometry_metadata % {
+                "table": self.quote_name(model._meta.db_table),
+                "column": self.quote_name(field.column),
+            }
+        )
+        self.execute(
+            self.sql_drop_spatial_index % {
+                "table": model._meta.db_table,
+                "column": field.column,
+            }
+        )
+
+    def create_model(self, model):
+        super(SpatialiteSchemaEditor, self).create_model(model)
+        # Create geometry columns
+        for sql in self.geometry_sql:
+            self.execute(sql)
+        self.geometry_sql = []
+
+    def delete_model(self, model):
+        from django.contrib.gis.db.models.fields import GeometryField
+        # Drop spatial metadata (dropping the table does not automatically remove them)
+        for field in model._meta.local_fields:
+            if isinstance(field, GeometryField):
+                self.remove_geometry_metadata(model, field)
+        super(SpatialiteSchemaEditor, self).delete_model(model)
+
+    def add_field(self, model, field):
+        from django.contrib.gis.db.models.fields import GeometryField
+        if isinstance(field, GeometryField):
+            # Populate self.geometry_sql
+            self.column_sql(model, field)
+            for sql in self.geometry_sql:
+                self.execute(sql)
+            self.geometry_sql = []
+        else:
+            super(SpatialiteSchemaEditor, self).add_field(model, field)
+
+    def remove_field(self, model, field):
+        from django.contrib.gis.db.models.fields import GeometryField
+        if isinstance(field, GeometryField):
+            self.remove_geometry_metadata(model, field)
+        super(SpatialiteSchemaEditor, self).remove_field(model, field)
+
+    def alter_db_table(self, model, old_db_table, new_db_table):
+        super(SpatialiteSchemaEditor, self).alter_db_table(model, old_db_table, new_db_table)
+        self.execute(
+            self.sql_update_geometry_columns % {
+                "old_table": self.quote_name(old_db_table),
+                "new_table": self.quote_name(new_db_table),
+            }
+        )