when db configuration is cancelled don't create config file

debian/template/postinst

@@ -46,16 +46,20 @@ case "$1" in
 
     . /etc/minerva/db.sh
     
-    if [ -z "$dbport" ]
-    then
-      dbport=5432
-    fi
+    # when configuration was cancelled don't create config file
+  	if [ ! -z "$dbuser" ]
+  	then
+      if [ -z "$dbport" ]
+      then
+        dbport=5432
+      fi
     
-    #create db configuration file 
-    echo "database.uri=jdbc:postgresql://$dbserver:$dbport/$dbname" > /etc/minerva/db.properties
-    echo "database.username=$dbuser" >> /etc/minerva/db.properties
-    echo "database.password=$dbpass" >> /etc/minerva/db.properties
+      #create db configuration file 
+      echo "database.uri=jdbc:postgresql://$dbserver:$dbport/$dbname" > /etc/minerva/db.properties
+      echo "database.username=$dbuser" >> /etc/minerva/db.properties
+      echo "database.password=$dbpass" >> /etc/minerva/db.properties
     
+    fi
     rm /etc/minerva/db.sh
 
     #we have to restart tomcat, because application was started on the old database and it might crash during deployment