Client Extensions

[steebchen]

Discussion for client extensions in the Go client.

This is useful to add hooks for queries and features such as RLS.

Some general notes:

• read only actions (so just having a callback) will be fairly easy to implement
• write actions will be more tricky (i.e. modifying queries), both design and implementation wise
• the first basic implementation will already enable a lot of use cases, such as limiting mutations to only logged-in users, time tracking, logging
• in contrast to the JS client, you won't be able to add custom queries. You can just do that with Go features itself by embedding structs

[steebchen]

A syntax idea for the extension API, inspired by the JS client.

extended := client.Prisma.Extend( // <- golang generics, yay! :D
	db.OnAll(func(model Model, operation Operation, query Query, args Args) Result {
		log.Printf("on all: model: %s, operation: %s, args: %+v", model, operation, Args)

		switch model {
		case UserModelName:
			log.Printf("is user!")
		}

		// TODO: how would you modify the query? 🤔
		return query()
	}),
	// is this too generic?
	db.On([]Operation{extension.FindUnique}, []Model{UserModelName}, func(model Model, operation Operation, query Query, args Args) Result {
		return query()
	}),
	// alternatively or additionally, all operation and model combinations with fully type-safe args
	db.OnUserFindFirst(func (args UserArgs, query UserFindFirstQuery) UserFindFirstResult {
		if args.Password != nil {
			log.Printf("user changed their password!")
		}
		return query()
	})
)

[steebchen]

I'm playing around here regarding syntax, this is highly experimental and not functional:

prisma-client-go/test/features/extension/default_test.go

Lines 22 to 124 in 2ddbf5e

	}{{
	name: "disallow deletes",
	before: nil,
	run: func(t *testing.T, client *PrismaClient, ctx cx) {
	extended := client.Prisma.Extend(
	ext.OnAll(func(ctx context.Context, model Model, operation Operation, args Args, run Run) (*Result, error) {
	log.Printf("on all: model: %s, operation: %s", model, operation)
	switch operation {
	case extension.DeleteOne, extension.DeleteMany:
	return nil, fmt.Errorf("deletes are not allowed")
	}
	return run()
	}),
	)
	log.Printf("extended: %+v", extended)
	},
	}, {
	name: "disallow mutations from non-logged in user",
	before: nil,
	run: func(t *testing.T, client *PrismaClient, ctx cx) {
	GetViewer := func(ctx context.Context) (*struct{}, bool) {
	return nil, true
	}
	extended := client.Prisma.Extend(
	ext.OnMutation(func(ctx context.Context, model Model, operation Operation, args Args, run Run) (*Result, error) {
	// adapt this to how you retrieve the current user from your HTTP context
	_, ok := GetViewer(ctx)
	if !ok {
	return nil, fmt.Errorf("not logged in")
	}
	log.Printf("on all: model: %s, operation: %s", model, operation)
	return run()
	}),
	)
	log.Printf("extended: %+v", extended)
	},
	}, {
	name: "track timing",
	before: nil,
	run: func(t *testing.T, client *PrismaClient, ctx cx) {
	extended := client.Prisma.Extend(
	ext.OnAll(func(ctx context.Context, model Model, operation Operation, args Args, run Run) (*Result, error) {
	now := time.Now()
	defer func() {
	log.Printf("timing: %s %s %s", model, operation, time.Since(now))
	}()
	return run()
	}),
	)
	log.Printf("extended: %+v", extended)
	},
	}, {
	name: "on operation",
	before: nil,
	run: func(t *testing.T, client *PrismaClient, ctx cx) {
	extended := client.Prisma.Extend(
	ext.OnOperation([]Operation{extension.FindUnique}, func(ctx context.Context, model Model, args Args, run Run) (*Result, error) {
	log.Printf("on operation: model: %s", model)
	return run()
	}),
	)
	log.Printf("extended: %+v", extended)
	},
	}, {
	name: "on model",
	before: nil,
	run: func(t *testing.T, client *PrismaClient, ctx cx) {
	extended := client.Prisma.Extend(
	ext.OnModel([]Model{UserModelName}, func(ctx context.Context, operation Operation, args Args, run Run) (*Result, error) {
	log.Printf("on operation: operation: %s", operation)
	return run()
	}),
	)
	log.Printf("extended: %+v", extended)
	},
	}, {
	name: "on model and operation",
	before: nil,
	run: func(t *testing.T, client *PrismaClient, ctx cx) {
	extended := client.Prisma.Extend(
	ext.On([]Operation{extension.FindUnique}, []Model{UserModelName}, func(ctx context.Context, model Model, operation Operation, args Args, run Run) (*Result, error) {
	return run()
	}),
	)
	log.Printf("extended: %+v", extended)
	},
	}, {
	name: "individual extensions",
	before: nil,
	run: func(t *testing.T, client *PrismaClient, ctx cx) {
	t.Skipf("not implemented yet")
	//extended := client.Prisma.Extend(
	// TODO this needs a lot more work as all the params have to be adapted to the respective method
	//ext.OnUserDeleteMany(func(ctx context.Context, query UserWhereParam, run Run) (*Result, error) {
	// return run()
	//}),
	//)
	//log.Printf("extended: %+v", extended)
	},
	}}