Greetings everyone! I am relatively new to prisma and wondering if I could get some highlight on the proper usage of prisma to kinda get match my expectations to the reality 🙂 Stack: apollo graphql + prisma + typegraphql (generating resolvers). schema.prisma: model SomeModel {… id… value Decimal…} model SomeAggregateModel {… id… aggregateValue Decimal…} business logic: (for example) - when SomeModel.value changes - do set SomeAggregateModel.aggregateValue=sum(all values from SomeModel.value) Use case • user in the frontend updates a value which gets updated in the backend through generated resolver UpdateSomeValueResolver • somehow the business logic gets triggered • upon update to SomeAggregateModel.aggregateValue the frontent gets notified and refreshes the display of aggregateValue to the user Questions: 1. Is it correct to expect the existence of ‘trigger’ mechanism which will initiate the business logic to run upon update to the SomeModel.value? 2. If such mechanism exists - would mind to point to some reading/manual/help/documentation reference as to how to enable this mechanism? 3. If such mechanism does NOT exist - what would be the most efficient way to implement the use case given the constraint of creating as less code as possible (i.e. in that case I guess there will have to be custom resolver I guess which front end will need to call to trigger the business logic of calculating the aggregatevalue) I would really appreciate advice on the use case above as I feel like the triggering must be there but so far not lucky enough to find it 🙈

Hello @Alexei Snisarenko thank you for posting your question and I glad that you're experimenting with Prisma. From your description this sounds like a use case for Prisma Middleware: https://www.prisma.io/docs/concepts/components/prisma-client/middleware @Joël , @Ryan might have more input for you!

Thank you @Vladi Stevanovic. It would really be helpful for me as I am trying to wrap my head around and grasp on this use case

@Alexei Snisarenko 👋 In this case, you can go for GraphQL subscriptions. This will make sure that any value that changes in your

SomeModel

for that you could perform an update in

SomeAggregateModel

. Another option is to use database triggers for the same. You can write a trigger in the Migration

.sql

file. This will be persisted in the database and would automatically run based on the condition that you provide in the trigger 🙂

Thank you @Ryan That’s where I was looking - subscriptions. Just wanted to make sure I’m digging in right direction. Still what would be your thought for is the prisma middleware useful for my case though?

Middleware’s would work as well in this case. You just would need to add a condition if the model being updated it the one you want.

Thanks for all the information!

Let me know how it goes and if you face any issues 🙂