图计算Dgraph系列1-学习环境搭建

一. 开发环境搭建

     因为是学习，所以选择docker的方式，操作命令如下：

docker pull dgraph/standalone

docker run --rm -it -p 8080:8080 -p 9080:9080 -p 8000:8000 -v ~/dgraph:/dgraph dgraph/standalone:latest

     url地址访问：http://localhost:8000/?latest

二. 代码开发

     主要使用java和go语言开发的方式

1. 搭建java开发环境

<dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

            <version>1.18.12</version>

        </dependency>

        <dependency>

            <groupId>com.google.code.gson</groupId>

            <artifactId>gson</artifactId>

            <version>2.8.5</version>

        </dependency>

        <dependency>

            <groupId>io.dgraph</groupId>

            <artifactId>dgraph4j</artifactId>

            <version>20.03.0</version>

        </dependency>

操作文档：https://github.com/dgraph-io/dgraph4j

2. 编写java代码

2.1 第一个demo

import com.am.Dgraph.bean.People;
import com.am.Dgraph.bean.Person;
import com.google.gson.Gson;
import com.google.protobuf.ByteString;
import io.dgraph.DgraphClient;
import io.dgraph.DgraphGrpc;
import io.dgraph.DgraphProto.Mutation;
import io.dgraph.DgraphProto.Operation;
import io.dgraph.DgraphProto.Response;
import io.dgraph.Transaction;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;

import java.util.Collections;
import java.util.Map;

public class OptDgraph{
    public static void main(String[] args) {
        opDgraph();
    }



    public static void opDgraph() {
        final DgraphClient dgraphClient = getDgraphClient();
        //删除schema + 数据
        dgraphClient.alter(Operation.newBuilder().setDropAll(true).build());

        String schema = "name: string @index(exact) .";
        Operation operation = Operation.newBuilder().setSchema(schema).build();
        dgraphClient.alter(operation);

        Gson gson = new Gson(); // For JSON encode/decode
        Transaction txn = dgraphClient.newTransaction();

        // Create data
        Person p = new Person();
        p.setName("Alice");

        // Serialize
        String json = gson.toJson(p);

        try {
            Mutation mutation = Mutation.newBuilder().setSetJson(ByteString.copyFromUtf8(json)).build();

            txn.mutate(mutation);
            txn.commit();
        } finally {
            txn.discard();
        }

        // Query
        String query =
                "query all($a: string){\n" + "all(func: eq(name, $a)) {\n" + "    name\n" + "  }\n" + "}";
        System.out.println(query);
        Map<String, String> vars = Collections.singletonMap("$a", "Alice");
        Response res = dgraphClient.newTransaction().queryWithVars(query, vars);

        // {"all":[{"name":"Alice"}]}, 这里的all主要是all(func: eq(name, $a) 的all控制，是个数组格式
        System.out.println(res.getJson().toStringUtf8());

        // Deserialize
//        //不符合Person的构造，所以返回Person(name=null)有问题
//        final Person person = gson.fromJson(res.getJson().toStringUtf8(), Person.class);
//        System.out.println(person);

        // Deserialize
        People ppl = gson.fromJson(res.getJson().toStringUtf8(), People.class);
//
//        // Print results
        System.out.printf("people found: %d\n", ppl.getAll().size());
        ppl.getAll().forEach(person -> System.out.println(person.getName()));
    }


    public static DgraphClient getDgraphClient() {
        ManagedChannel channel =
                ManagedChannelBuilder.forAddress("localhost",9080).usePlaintext().build();

        DgraphGrpc.DgraphStub stub = DgraphGrpc.newStub(channel);

        DgraphClient dgraphClient = new DgraphClient(stub);
        return  dgraphClient;
    }

}

输出展示：

query all($a: string){

all(func: eq(name, $a)) {

    name

  }

}

{"all":[{"name":"Alice"}]}

people found: 1

Alice

3. go语言开发

3.1 环境

go get -u github.com/dgraph-io/dgo/v2

下载依赖模块，成功后产生go.mod

3.2 demo开发

import (

	"context"

	"encoding/json"

	"flag"

	"fmt"

	"log"



	"github.com/dgraph-io/dgo/v2"

	"github.com/dgraph-io/dgo/v2/protos/api"

	"google.golang.org/grpc"

)



var (

	dgraph = flag.String("d", "localhost:9080", "Dgraph Alpha address")

)



func main() {

	optDgraph()

}





func optDgraph() {

	flag.Parse()

	conn, err := grpc.Dial(*dgraph, grpc.WithInsecure())

	if err != nil {

		log.Fatal(err)

	}



	client := dgo.NewDgraphClient(api.NewDgraphClient(conn))

	ctx := context.Background()

	err =  client.Alter(ctx, &api.Operation{DropAll: true})

	if err != nil {

		log.Fatal(err)

	}



	schema := "name: string @index(term) . \n" +

		      "age: int .\n" +

		     "type Person {\n" +

					"\tname\n" +

					"\tage\n" +

		     "}"

	err =  client.Alter(ctx, &api.Operation{Schema: schema})

	if err != nil {

		log.Fatal(err)

	}



	person := &Person{

		Name: "Alice",

		Age: 24,

	}



	mu := &api.Mutation{CommitNow: true}

	pb, err := json.Marshal(person)

	if err != nil {

		log.Fatal(err)

	}



	mu.SetJson = pb

	_, err = client.NewTxn().Mutate(ctx, mu)

	if err != nil {

		log.Fatal(err)

	}



	queryAll := `{

				  all(func: has(name)) {

					uid,

					name,

					age

				  }

				}`



	res, err :=  client.NewTxn().Query(ctx, queryAll)

	if err != nil {

		log.Fatal(err)

	}

	fmt.Println(res)



	queryAs := `query eq($name: string){ eq(func: eq(name, $name)) {

					uid,

					name,

					age

				  } 

				}`

	res, err = client.NewTxn().QueryWithVars(ctx, queryAs,  map[string]string{"$name": "Alice"})

	if err != nil {

		log.Fatal(err)

	}

	fmt.Println(res)

}



type Person struct {

	Uid     string   `json:"uid"`

	Name    string   `json:"name"`

	Age     int      `json:"age"`

}