Cannot set value in [uid] predicate in golang: "Input for predicate "predicate_name" of type uid is scalar"

Users Dgraph
5

I finally did it.
I can refer to dgo/example_set_object_test.go at master · dgraph-io/dgo · GitHub.
There every one who wonder can see how to link nodes.

There is my working prototype. Is that Go way to do this?

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"

	"github.com/dgraph-io/dgo/v210"
	"github.com/dgraph-io/dgo/v210/protos/api"
	"google.golang.org/grpc"
)

const schema = `rule.name: string @index(exact) .
device.name: string @index(exact) .
device.rules: [uid] .
`

type Rule struct {
	Uid  int    `json:"uid,omitempty"`
	Name string `json:"rule.name,omitempty"`
}
type Device struct {
	Uid   int    `json:"uid,omitempty"`
	Name  string `json:"device.name,omitempty"`
	Rules []Rule `json:"device.rules,omitempty"`
}

var ctx = context.TODO()

func main() {
	// Set db connection
	conn, err := grpc.Dial("localhost:9080", grpc.WithInsecure())
	if err != nil {
		log.Fatal(err)
	}
	defer conn.Close()
	dgraphClient := dgo.NewDgraphClient(api.NewDgraphClient(conn))

	op := &api.Operation{
		Schema: schema,
	}
	err = dgraphClient.Alter(ctx, op)
	if err != nil {
		panic(err)
	}

	// Create rule
	txn := dgraphClient.NewTxn()
	defer txn.Discard(ctx)

	r := Rule{
		Uid:  1,
		Name: "Rule1",
	}

	pb, err := json.Marshal(r)
	if err != nil {
		log.Fatal(err)
	}

	mu := &api.Mutation{
		SetJson:   pb,
		CommitNow: true,
	}
	res, err := txn.Mutate(ctx, mu)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(res)

	// Create Device
	txn = dgraphClient.NewTxn()
	defer txn.Discard(ctx)

	d := Device{
		Uid:   2,
		Name:  "Device1",
		Rules: []Rule{{Uid: 1}},
	}

	pb, err = json.Marshal(d)
	if err != nil {
		log.Fatal(err)
	}

	mu = &api.Mutation{
		SetJson:   pb,
		CommitNow: true,
	}
	res, err = txn.Mutate(ctx, mu)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(res)
}

As I understood it will not fully copy rule in the device but just write it uid in device.rules.