diff --git a/src/datasources/db/cargobikeAPI.ts b/src/datasources/db/cargobikeAPI.ts
index 27c3d24..6cd8304 100644
--- a/src/datasources/db/cargobikeAPI.ts
+++ b/src/datasources/db/cargobikeAPI.ts
@@ -6,6 +6,7 @@ import { BikeEvent } from '../../model/BikeEvent';
 import { Equipment } from '../../model/Equipment';
 import { Engagement } from '../../model/Engagement';
 import { Provider } from '../../model/Provider';
+import { TimeFrame } from '../../model/TimeFrame';
 
 /**
  * extended datasource to feed resolvers with data about cargoBikes
@@ -56,6 +57,14 @@ export class CargoBikeAPI extends DataSource {
             .loadMany();
     }
 
+    async cargoBikeByTimeFrameId (id: number) {
+        return await this.connection.getRepository(TimeFrame)
+            .createQueryBuilder('timeframe')
+            .relation(TimeFrame, 'cargoBike')
+            .of(id)
+            .loadOne();
+    }
+
     async lockCargoBike (id: number, req: any, dataSources: any) {
         if (await this.lockEntity(CargoBike, 'cargobike', id, req, dataSources)) {
             return this.findCargoBikeById(id);
diff --git a/src/datasources/db/lendingstationAPI.ts b/src/datasources/db/lendingstationAPI.ts
index c371cff..614c704 100644
--- a/src/datasources/db/lendingstationAPI.ts
+++ b/src/datasources/db/lendingstationAPI.ts
@@ -42,6 +42,14 @@ export class LendingStationAPI extends DataSource {
             .getOne().catch(() => { return null; });
     }
 
+    async lendingStationByTimeFrameId (id: number) {
+        await this.connection.getRepository(TimeFrame)
+            .createQueryBuilder('timeframe')
+            .relation(TimeFrame, 'lendingStation')
+            .of(id)
+            .loadOne();
+    }
+
     async timeFrames (offset: number, limit: number) {
         return await this.connection.getRepository(TimeFrame)
             .createQueryBuilder('timeframe')
@@ -127,28 +135,32 @@ export class LendingStationAPI extends DataSource {
 
     async createTimeFrame (timeFrame: any) {
         let inserts: any;
-        await this.connection.transaction(async (entityManager: EntityManager) => {
-            if (timeFrame.to === undefined) {
-                timeFrame.to = '';
-            }
-            timeFrame.dateRange = '[' + timeFrame.from + ',' + timeFrame.to + ')';
-            inserts = await entityManager.getRepository(TimeFrame)
-                .createQueryBuilder('timeframe')
-                .insert()
-                .returning('*')
-                .values([timeFrame])
-                .execute();
-            await entityManager.getRepository(TimeFrame)
-                .createQueryBuilder()
-                .relation(TimeFrame, 'cargoBike')
-                .of(inserts.identifiers[0].id)
-                .set(timeFrame.cargoBikeId);
-            await entityManager.getRepository(TimeFrame)
-                .createQueryBuilder()
-                .relation(TimeFrame, 'lendingStation')
-                .of(inserts.identifiers[0].id)
-                .set(timeFrame.lendingStationId);
-        });
+        try {
+            await this.connection.transaction(async (entityManager: EntityManager) => {
+                if (timeFrame.to === undefined) {
+                    timeFrame.to = '';
+                }
+                timeFrame.dateRange = '[' + timeFrame.from + ',' + timeFrame.to + ')';
+                inserts = await entityManager.getRepository(TimeFrame)
+                    .createQueryBuilder('timeframe')
+                    .insert()
+                    .returning('*')
+                    .values([timeFrame])
+                    .execute();
+                await entityManager.getRepository(TimeFrame)
+                    .createQueryBuilder()
+                    .relation(TimeFrame, 'cargoBike')
+                    .of(inserts.identifiers[0].id)
+                    .set(timeFrame.cargoBikeId);
+                await entityManager.getRepository(TimeFrame)
+                    .createQueryBuilder()
+                    .relation(TimeFrame, 'lendingStation')
+                    .of(inserts.identifiers[0].id)
+                    .set(timeFrame.lendingStationId);
+            });
+        } catch (e) {
+            return new GraphQLError('Transaction could not be completed');
+        }
         inserts.generatedMaps[0].id = inserts.identifiers[0].id;
         return inserts.generatedMaps[0];
     }
diff --git a/src/resolvers/lendingstationResolvers.ts b/src/resolvers/lendingstationResolvers.ts
index 7b43d0f..10fe8e3 100644
--- a/src/resolvers/lendingstationResolvers.ts
+++ b/src/resolvers/lendingstationResolvers.ts
@@ -45,7 +45,14 @@ export default {
             return (parent.dateRange as string).split(',')[0].replace('[', '');
         },
         to (parent: any, __: any, { dataSources, req }: { dataSources: any, req: any }) {
-            return (parent.dateRange as string).split(',')[1].replace(')', '');
+            const str = (parent.dateRange as string).split(',')[1].replace(')', '');
+            return (str.length > 0) ? str : null;
+        },
+        cargoBike (parent: any, __: any, { dataSources, req }: { dataSources: any, req: any }) {
+            return dataSources.cargoBikeAPI.cargoBikeByTimeFrameId(parent.id);
+        },
+        lendingStation (parent: any, __: any, { dataSources, req }: { dataSources: any, req: any }) {
+            return dataSources.lendingStationAPI.lendingStationByTimeFrameId(parent.id);
         }
     },
     Mutation: {
diff --git a/src/schema/type-defs.ts b/src/schema/type-defs.ts
index 4b4da45..7827638 100644
--- a/src/schema/type-defs.ts
+++ b/src/schema/type-defs.ts
@@ -659,7 +659,9 @@ input LoanPeriodsInput {
 "(dt. Zeitscheibe) When was a bike where"
 type TimeFrame {
     id: ID!
+    "format YYYY-MM-dd"
     from: Date!
+    "formmat YYYY-MM-dd"
     to: Date
     note: String
     lendingStation: LendingStation!
@@ -670,8 +672,8 @@ input TimeFrameCreateInput {
     from: Date!
     to: Date
     note: String
-    lendingStationID: ID!
-    cargoBikeID: ID!
+    lendingStationId: ID!
+    cargoBikeId: ID!
 }
 
 input TimeFrameUpdateInput {