Add prune images endpoint.

Use many-to-many relationship between images and templates.

gns3server/db/models/images.py

@@ -15,10 +15,18 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from sqlalchemy import Column, String, Integer, BigInteger
+from sqlalchemy import Table, Column, String, Integer, ForeignKey, BigInteger
 from sqlalchemy.orm import relationship
 
-from .base import BaseTable
+from .base import Base, BaseTable, GUID
+
+
+image_template_link = Table(
+    "images_templates_link",
+    Base.metadata,
+    Column("image_id", Integer, ForeignKey("images.id", ondelete="CASCADE")),
+    Column("template_id", GUID, ForeignKey("templates.template_id", ondelete="CASCADE"))
+)
 
 
 class Image(BaseTable):
@@ -32,4 +40,4 @@ class Image(BaseTable):
     path = Column(String)
     checksum = Column(String)
     checksum_algorithm = Column(String)
-    templates = relationship("Template")
+    templates = relationship("Template", secondary=image_template_link, back_populates="images")

gns3server/db/models/templates.py

@@ -17,8 +17,10 @@
 
 
 from sqlalchemy import Boolean, Column, String, Integer, ForeignKey, PickleType
+from sqlalchemy.orm import relationship
 
 from .base import BaseTable, generate_uuid, GUID
+from .images import image_template_link
 
 
 class Template(BaseTable):
@@ -34,8 +36,7 @@ class Template(BaseTable):
     compute_id = Column(String)
     usage = Column(String)
     template_type = Column(String)
-
-    image_id = Column(Integer, ForeignKey('images.id', ondelete="CASCADE"))
+    images = relationship("Image", secondary=image_template_link, back_populates="templates")
 
     __mapper_args__ = {
         "polymorphic_identity": "templates",