bug(web): Inform user when deleted topology is still used

This change fixes #135 which showed that trying to delete a topology
used by a scenario would result in nothing happening in the UI and a 500
error being returned by the server. We check whether a scenario still
references the topology and show an error to the user if that happens.

Fixes #135

2 files changed, 26 insertions, 0 deletions

diff --git a/opendc-web/opendc-web-server/src/main/java/org/opendc/web/server/rest/user/TopologyResource.java b/opendc-web/opendc-web-server/src/main/java/org/opendc/web/server/rest/user/TopologyResource.java
index 2b66b64b..71491801 100644
--- a/opendc-web/opendc-web-server/src/main/java/org/opendc/web/server/rest/user/TopologyResource.java
+++ b/opendc-web/opendc-web-server/src/main/java/org/opendc/web/server/rest/user/TopologyResource.java
@@ -22,10 +22,12 @@
 
 package org.opendc.web.server.rest.user;
 
+import io.quarkus.hibernate.orm.panache.Panache;
 import io.quarkus.security.identity.SecurityIdentity;
 import java.time.Instant;
 import java.util.List;
 import javax.annotation.security.RolesAllowed;
+import javax.persistence.PersistenceException;
 import javax.transaction.Transactional;
 import javax.validation.Valid;
 import javax.ws.rs.Consumes;
@@ -193,6 +195,14 @@ public final class TopologyResource {
 
         entity.updatedAt = Instant.now();
         entity.delete();
+
+        try {
+            // Flush the results, so we can check whether the constraints are not violated
+            Panache.flush();
+        } catch (PersistenceException e) {
+            throw new WebApplicationException("Topology is still in use", 403);
+        }
+
         return UserProtocol.toDto(entity, auth);
     }
 }
diff --git a/opendc-web/opendc-web-server/src/test/java/org/opendc/web/server/rest/user/TopologyResourceTest.java b/opendc-web/opendc-web-server/src/test/java/org/opendc/web/server/rest/user/TopologyResourceTest.java
index 21e35b09..c0746e7a 100644
--- a/opendc-web/opendc-web-server/src/test/java/org/opendc/web/server/rest/user/TopologyResourceTest.java
+++ b/opendc-web/opendc-web-server/src/test/java/org/opendc/web/server/rest/user/TopologyResourceTest.java
@@ -355,4 +355,20 @@ public final class TopologyResourceTest {
                 .statusCode(200)
                 .contentType(ContentType.JSON);
     }
+
+    /**
+     * Test to delete a topology that is still being used by a scenario.
+     */
+    @Test
+    @TestSecurity(
+            user = "owner",
+            roles = {"openid"})
+    public void testDeleteUsed() {
+        given().pathParam("project", "1")
+                .when()
+                .delete("/1") // Topology 1 is still used by scenario 1 and 2
+                .then()
+                .statusCode(403)
+                .contentType(ContentType.JSON);
+    }
 }