diff --git a/src/datasources/db/participantAPI.ts b/src/datasources/db/participantAPI.ts
index d480f9e..311ba26 100644
--- a/src/datasources/db/participantAPI.ts
+++ b/src/datasources/db/participantAPI.ts
@@ -179,7 +179,7 @@ export class ParticipantAPI extends DataSource {
                 .values([participant])
                 .returning('*')
                 .execute();
-            await entityManager.getRepository(Participant)
+            participant.workshopIds && await entityManager.getRepository(Participant)
                 .createQueryBuilder('w')
                 .relation(Participant, 'workshopIds')
                 .of(participant.id)
@@ -211,8 +211,8 @@ export class ParticipantAPI extends DataSource {
                 .update()
                 .set({ ...participant })
                 .where('id = :id', { id: participant.id })
-                .execute().then(value => { if (value.affected !== 1) { throw new GraphQLError('ID not found'); } });
-            await entityManager.getRepository(Participant)
+                .execute().then(value => { if (value.affected !== 1) { throw new UserInputError('ID not found'); } });
+            workshops && await entityManager.getRepository(Participant)
                 .createQueryBuilder('w')
                 .relation(Participant, 'workshopIds')
                 .of(participant.id)
diff --git a/src/resolvers/participantResolvers.ts b/src/resolvers/participantResolvers.ts
index ed058e1..89deb3e 100644
--- a/src/resolvers/participantResolvers.ts
+++ b/src/resolvers/participantResolvers.ts
@@ -113,13 +113,6 @@ export default {
                 return new GraphQLError('Insufficient Permissions');
             }
         },
-        from (parent: any) {
-            return (parent.dateRange as string).split(',')[0].replace('[', '');
-        },
-        to (parent: any) {
-            const str = (parent.dateRange as string).split(',')[1].replace(')', '');
-            return (str.length > 0) ? str : null;
-        },
         isLockedByMe: (parent: any, __: any, { req }: { req: any }) => isLockedByMe(parent, { req }),
         isLocked: (parent: any, __: any, { req }: { req: any }) => isLocked(parent, { req })
     },
diff --git a/src/schema/type-defs.ts b/src/schema/type-defs.ts
index afc7d7f..e72012c 100644
--- a/src/schema/type-defs.ts
+++ b/src/schema/type-defs.ts
@@ -550,8 +550,7 @@ export default gql`
     type Engagement {
         id: ID!
         engagementType: EngagementType!
-        from: Date!
-        to: Date
+        dateRange: DateRange!
         participant: Participant!
         cargoBike: CargoBike!
         isLocked: Boolean!
@@ -563,18 +562,14 @@ export default gql`
 
     input EngagementCreateInput {
         engagementTypeId: ID!
-        "will use CURRENT_DATE if not set"
-        from: Date
-        "will use infinit if not set"
-        to: Date
+        dateRange: DateRangeInput
         participantId: ID!
         cargoBikeId: ID!
     }
     input EngagementUpdateInput {
         id: ID!
         engagementTypeId: ID
-        from: Date
-        to: Date
+        dateRange: DateRangeInput
         participantId: ID
         cargoBikeId: ID
         keepLock: Boolean