Dgraph

// Dgraph Node.js 클라이언트 (dgraph-js)
const dgraph = require('dgraph-js');
const grpc = require('@grpc/grpc-js');

// 클라이언트 연결
const clientStub = new dgraph.DgraphClientStub(
    'localhost:9080',
    grpc.credentials.createInsecure()
);
const dgraphClient = new dgraph.DgraphClient(clientStub);

async function setSchema() {
    const schema = `
        type Person {
            name: string @index(exact, term) .
            age: int @index(int) .
            email: string @index(exact) @upsert .
            friends: [Person] @reverse .
        }
    `;

    const op = new dgraph.Operation();
    op.setSchema(schema);
    await dgraphClient.alter(op);
    console.log('스키마 설정 완료');
}

async function createData() {
    const txn = dgraphClient.newTxn();

    try {
        const data = {
            uid: '_:alice',
            'dgraph.type': 'Person',
            name: 'Alice',
            age: 28,
            email: 'alice@example.com',
            friends: [
                {
                    uid: '_:bob',
                    'dgraph.type': 'Person',
                    name: 'Bob',
                    age: 32,
                    email: 'bob@example.com'
                }
            ]
        };

        const mu = new dgraph.Mutation();
        mu.setSetJson(data);
        mu.setCommitNow(true);

        const response = await txn.mutate(mu);
        console.log('생성된 UID:', response.getUidsMap().toObject());

        return response.getUidsMap();

    } finally {
        await txn.discard();
    }
}

async function queryData() {
    const query = `
    {
        people(func: has(name), orderasc: name) {
            uid
            name
            age
            email
            friends {
                name
                age
            }
        }
    }
    `;

    const txn = dgraphClient.newTxn({ readOnly: true });

    try {
        const response = await txn.query(query);
        const result = response.getJson();

        console.log('\n전체 사용자:');
        result.people.forEach(person => {
            console.log(`  ${person.name} (${person.age}세)`);
            if (person.friends) {
                person.friends.forEach(friend => {
                    console.log(`    → ${friend.name}`);
                });
            }
        });

    } finally {
        await txn.discard();
    }
}

async function graphqlMutation() {
    // GraphQL 엔드포인트 사용 (HTTP)
    const fetch = require('node-fetch');

    const mutation = `
        mutation AddPerson($input: AddPersonInput!) {
            addPerson(input: [$input]) {
                person {
                    uid
                    name
                    age
                }
            }
        }
    `;

    const variables = {
        input: {
            name: 'David',
            age: 35,
            email: 'david@example.com'
        }
    };

    const response = await fetch('http://localhost:8080/graphql', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ query: mutation, variables })
    });

    const result = await response.json();
    console.log('\nGraphQL 뮤테이션 결과:', result);
}

async function subscriptionExample() {
    // 실시간 구독 (WebSocket)
    const { SubscriptionClient } = require('subscriptions-transport-ws');
    const ws = require('ws');

    const client = new SubscriptionClient(
        'ws://localhost:8080/graphql',
        { reconnect: true },
        ws
    );

    const subscription = `
        subscription WatchPeople {
            queryPerson {
                name
                age
            }
        }
    `;

    client.request({ query: subscription }).subscribe({
        next: data => console.log('변경 감지:', data),
        error: err => console.error('구독 오류:', err)
    });
}

// 실행
(async () => {
    await setSchema();
    await createData();
    await queryData();
    await graphqlMutation();
    clientStub.close();
})();

# ============================================
# GraphQL 스키마 정의
# ============================================

type Person {
    id: ID!
    name: String! @search(by: [exact, term])
    age: Int @search(by: [int])
    email: String! @id  # 유니크 식별자
    friends: [Person] @hasInverse(field: friends)
    posts: [Post] @hasInverse(field: author)
}

type Post {
    id: ID!
    title: String! @search(by: [fulltext])
    content: String
    author: Person!
    tags: [String] @search(by: [exact])
    createdAt: DateTime!
}


# ============================================
# GraphQL 쿼리 예제
# ============================================

# 모든 사용자와 친구 조회
query {
    queryPerson {
        name
        age
        friends {
            name
        }
    }
}

# 필터링과 페이지네이션
query {
    queryPerson(
        filter: { age: { ge: 25 } }
        order: { asc: name }
        first: 10
        offset: 0
    ) {
        name
        age
        email
    }
}


# ============================================
# DQL (Dgraph Query Language) 예제
# ============================================

# 기본 쿼리
{
    people(func: type(Person), orderasc: name, first: 10) {
        uid
        name
        age
        email
    }
}

# 그래프 순회 - 친구의 친구 찾기
{
    alice(func: eq(name, "Alice")) {
        name
        friends {
            name
            friends {
                name
            }
        }
    }
}

# 재귀 쿼리 - N단계 관계 탐색
{
    connections(func: eq(name, "Alice")) @recurse(depth: 3) {
        name
        friends
    }
}

# 필터와 집계
{
    stats(func: type(Person)) @filter(ge(age, 25)) {
        count(uid)
        avg_age: avg(age)
        min_age: min(age)
        max_age: max(age)
    }
}

# 전문 검색
{
    search(func: alloftext(content, "machine learning AI")) {
        title
        content
        author {
            name
        }
    }
}

# 지리공간 쿼리
{
    nearby(func: near(location, [37.5665, 126.9780], 5000)) {
        name
        location
    }
}


# ============================================
# 뮤테이션 예제
# ============================================

# GraphQL 뮤테이션
mutation {
    addPerson(input: [{
        name: "Eve"
        age: 30
        email: "eve@example.com"
        friends: { name: "Alice" }
    }]) {
        person {
            id
            name
        }
    }
}

# DQL 뮤테이션 (RDF 형식)
{
    set {
        _:eve  "Person" .
        _:eve  "Eve" .
        _:eve  "30"^^ .
        _:eve  "eve@example.com" .
    }
}