devid checked to be not existent on creation

app/app.log

 [2020-09-13 17:53:00,310] INFO in views: Logged in superuser admin
 [2020-09-13 17:55:00,520] INFO in views: superuser admin created new application THSO 49f4d289
 [2020-09-13 17:58:38,291] INFO in views: superuser admin added new device ESP32 for application 49f4d289
+[2020-10-01 15:08:14,780] INFO in views: Logged in superuser admin
+[2020-10-01 15:08:37,331] INFO in views: Logged in superuser admin
+[2020-10-01 15:10:09,547] INFO in views: superuser admin failed to add new device tricky for application 8cc6f4b1. Cause: existing devid
+[2020-10-01 15:11:29,771] INFO in views: superuser admin failed to add new device tricky for application 8cc6f4b1. Cause: existing devid
+[2020-10-01 15:11:42,083] INFO in views: superuser admin added new device tricky for application 8cc6f4b1
+[2020-10-01 15:11:55,695] INFO in views: superuser admin deleted for application 8cc6f4b1 device 2

app/app/dao/device/device.py

@@ -136,6 +136,7 @@ def get(cur, appkey, dev_id):
         dev[3] = json.loads(dev[3].tobytes())
         return (True, dev)
 
+
 @with_psql
 def update(cur, appkey, devid, name, desc):
     tn = 'devices_'+appkey
@@ -221,3 +222,20 @@ def get_count_by_user(cur, username):
         count += cur.fetchone()[0]
 
     return count
+
+
+@with_psql
+def check_devid(cur, appkey, dev_id):
+    tn = 'devices_' +str(appkey)
+    query = """
+    SELECT dev_id FROM 
+        {}
+    WHERE
+        dev_id = %s
+    """
+    cur.execute(
+        sql.SQL(query).format(sql.Identifier(tn)), [dev_id])
+    dev = cur.fetchone()
+   
+    return dev is None
+

app/app/views.py

@@ -217,24 +217,29 @@ def application_add_device(appkey):
         dev_list = dd.get_list(appkey)
         return render_template('views/public/add-device.html', app=ap[1], free_ids=misc.prep_id_range(dev_list[1]), models=ddm.MODELS)
     elif request.method == 'POST':
-        ddmin = ddm.extract(request)
-       
-        res = dd.create_ddm(request.form['devname'], request.form['devid'], appkey, request.form['devdesc'], ddmin)
-        if not res[0]:
-            app.logger.error('%s %s failed to add device for application %s - %s', session['role'], session['name'], appkey, res[1])
-            flash('Error: {}'.format(res[1]), 'danger')
-            return redirect(request.url)
-        else:
-            res = data.create_table_ddm(appkey, request.form['devid'])
+        if dd.check_devid(appkey, request.form['devid']):
+            ddmin = ddm.extract(request)
+           
+            res = dd.create_ddm(request.form['devname'], request.form['devid'], appkey, request.form['devdesc'], ddmin)
             if not res[0]:
                 app.logger.error('%s %s failed to add device for application %s - %s', session['role'], session['name'], appkey, res[1])
-                dd.delete(session['appkey'], request.form['devid'])
                 flash('Error: {}'.format(res[1]), 'danger')
                 return redirect(request.url)
             else:
-                app.logger.info('%s %s added new device %s for application %s', session['role'], session['name'], request.form['devname'], appkey)
-                flash('Device added', 'success')
-                return redirect(url_for('application', appkey=appkey))
+                res = data.create_table_ddm(appkey, request.form['devid'])
+                if not res[0]:
+                    app.logger.error('%s %s failed to add device for application %s - %s', session['role'], session['name'], appkey, res[1])
+                    dd.delete(session['appkey'], request.form['devid'])
+                    flash('Error: {}'.format(res[1]), 'danger')
+                    return redirect(request.url)
+                else:
+                    app.logger.info('%s %s added new device %s for application %s', session['role'], session['name'], request.form['devname'], appkey)
+                    flash('Device added', 'success')
+                    return redirect(url_for('application', appkey=appkey))
+        else:
+            app.logger.info('%s %s failed to add new device %s for application %s. Cause: existing devid', session['role'], session['name'], request.form['devname'], appkey)
+            flash('Error: Selected Device ID already used, pick another one.', 'danger')
+            return redirect(request.url)
 
 
 @app.route('/application/<appkey>/device/<devid>/delete')

app/app/views_admin.py

@@ -135,25 +135,30 @@ def administration_user_application_add_device(name, appkey):
         dev_list = dd.get_list(appkey)
         return render_template('views/admin/user-application-add-device.html', app=ap[1], free_ids=misc.prep_id_range(dev_list[1]), models=ddm.MODELS, user=name)
     elif request.method == 'POST':
-        ddmin = ddm.extract(request)
-        res = dd.create_ddm(request.form['devname'], request.form['devid'], appkey, request.form['devdesc'], ddmin)
+        if dd.check_devid(appkey, request.form['devid']):
+            ddmin = ddm.extract(request)
+            res = dd.create_ddm(request.form['devname'], request.form['devid'], appkey, request.form['devdesc'], ddmin)
 
-        if not res[0]:
-            app.logger.error('Administrator %s failed to add device application %s for %s - %s', session['name'], appkey, name, res[1])
-            flash('Error: {}'.format(res[1]), 'danger')
-            return redirect(request.url)
-        
-        res = data.create_table_ddm(appkey, request.form['devid'])
-    
-        if not res[0]:
-            dd.delete(appkey, request.form['devid'])
-            app.logger.error('Administrator %s failed to add device application %s for %s - %s', session['name'], appkey, name, res[1])
-            flash('Error: {}'.format(res[1]), 'danger')
-            return rendirect(request.url)
-        
-        app.logger.warning('Administrator %s added new device %s application %s for %s', session['name'], request.form['devid'], appkey, name)
+            if not res[0]:
+                app.logger.error('Administrator %s failed to add device application %s for %s - %s', session['name'], appkey, name, res[1])
+                flash('Error: {}'.format(res[1]), 'danger')
+                return redirect(request.url)
+            
+            res = data.create_table_ddm(appkey, request.form['devid'])
         
-        return redirect(url_for('administration_user_application', name=name, appkey=appkey))
+            if not res[0]:
+                dd.delete(appkey, request.form['devid'])
+                app.logger.error('Administrator %s failed to add device application %s for %s - %s', session['name'], appkey, name, res[1])
+                flash('Error: {}'.format(res[1]), 'danger')
+                return rendirect(request.url)
+            
+            app.logger.warning('Administrator %s added new device %s application %s for %s', session['name'], request.form['devid'], appkey, name)
+            
+            return redirect(url_for('administration_user_application', name=name, appkey=appkey))
+        else:
+            app.logger.info('%s %s failed to add new device %s for application %s. Cause: existing devid', session['role'], session['name'], request.form['devname'], appkey)
+            flash('Error: Selected Device ID already used, pick another one.', 'danger')
+            return redirect(request.url)
 
 
 @app.route('/administration/<name>/application/<appkey>/device/<devid>')