學(xué)習(xí)來源：https://github.com/dgraph-io/pydgraph
dgraph說明文檔https://dgraph.io/docs/get-started/

安裝pydgraph

pip install pydgraph

官方文檔說明骚亿，為了避免在添加復(fù)合憑據(jù)或使用客戶端授權(quán)時出現(xiàn)問題沪哺，請安裝gRPC 1.19.0版本:

pip install grpcio==1.19.0

我直接pip install grpcio了漫雷，沒設(shè)置版本
安裝完成后在自己的環(huán)境中驗(yàn)證一下是否安裝成功

import pydgraph
pydgraph.VERSION

連接到dgraph

鏈接dgraph之前先啟動zero和alpha湃崩，ratel可以做實(shí)驗(yàn)的時候查看效果用
啟動之后創(chuàng)建client_stub和client，類似py2neo里的Graph連接到neo4j

client_stub = pydgraph.DgraphClientStub('localhost:9080')
client = pydgraph.DgraphClient(client_stub)

刪除dgraph中所有數(shù)據(jù)

client.alter(pydgraph.Operation(drop_all=True))

創(chuàng)建SCHEMA

schema = """
    name: string @index(exact) .
    friend: [uid] @reverse .
    age: int .
    married: bool .
    loc: geo .
    dob: datetime .
    type Person {
        name
        friend
        age
        married
        loc
        dob
    }
    """
client.alter(pydgraph.Operation(schema=schema))

這里的schema和dgraph中編輯的schema是相同格式的（注意三引號银择，否則報(bào)錯）

Edit Schema File

用rdf格式創(chuàng)建數(shù)據(jù)

后幾行()小括號里面的是邊屬性斑司，不可設(shè)置中文

txbb = '''
<_:person001> <name> "丁丁" .
<_:person001> <'顏色'> "紫色" .
<_:person001> <antenna_shape> "三角形" .
<_:person001> <height> "304" .
<_:person002> <name> "迪西" .
<_:person002> <color> "綠色" .
<_:person002> <antenna_shape> "直線形" .
<_:person002> <height> "259" .
<_:person003> <name> "拉拉" .
<_:person003> <color> "黃色" .
<_:person003> <antenna_shape> "螺旋" .
<_:person002> <height> "245" .
<_:person004> <name> "小波" .
<_:person004> <color> "紅色" .
<_:person004> <antenna_shape> "圓形" .
<_:person004> <height> "182" .
<_:person001> <'朋友'> <_:person002> (friendship=1.0) . 
<_:person001> <friend> <_:person003> (friendship=0.9) . 
<_:person001> <friend> <_:person004> (friendship=0.8) . 
<_:person002> <friend> <_:person003> . 
<_:person002> <friend> <_:person004> . 
<_:person003> <friend> <_:person004> . 
'''
txn = client.txn()
txn.mutate(set_nquads=txbb)
txn.commit()

用json格式創(chuàng)建數(shù)據(jù)

def create_data(client):
    # Create a new transaction.
    txn = client.txn()
    try:
        # Create data.
        p = {
            'uid': '_:alice',
            'dgraph.type': 'Person',
            'name': 'Alice',
            'age': 26,
            'married': True,
            'loc': {
                'type': 'Point',
                'coordinates': [1.1, 2],
            },
            'dob': datetime.datetime(1980, 1, 1, 23, 0, 0, 0).isoformat(),
            'friend': [
                {
                    'uid': '_:bob',
                    'dgraph.type': 'Person',
                    'name': 'Bob',
                    'age': 24,
                }
            ],
            'school': [
                {
                    'name': 'Crown Public School',
                }
            ]
        }

        # Run mutation.
        response = txn.mutate(set_obj=p)

        # Commit transaction.
        txn.commit()

        # Get uid of the outermost object (person named "Alice").
        # response.uids returns a map from blank node names to uids.
        print('Created person named "Alice" with uid = {}'.format(response.uids['alice']))

    finally:
        # Clean up. Calling this after txn.commit() is a no-op and hence safe.
        txn.discard()

邊屬性在json中設(shè)置格式：（例如上例中friend關(guān)系）

'friend': [
                {
                    'uid': '_:bob',
                    'dgraph.type': 'Person',
                    'name': 'Bob',
                    'age': 24,
                    'friend|boyfriend': True,
                }
            ],

刪除數(shù)據(jù)

def delete_data(client):
    # Create a new transaction.
    txn = client.txn()
    try:
        query1 = """query all($a: string) {
            all(func: eq(name, $a)) {
               uid
            }
        }"""
        variables1 = {'$a': 'Bob'}
        res1 = client.txn(read_only=True).query(query1, variables=variables1)
        ppl1 = json.loads(res1.json)
        for person in ppl1['all']:
            print("Bob's UID: " + person['uid'])
            txn.mutate(del_obj=person)
            print('Bob deleted')
        txn.commit()

    finally:
        txn.discard()

查詢數(shù)據(jù)

數(shù)據(jù)以字典的格式返回

def query_alice(client):
    # Run query.
    query = """query all($a: string) {
        all(func: eq(name, $a)) {
            uid
            name
            age
            married
            loc
            dob
            friend {
                name
                age
            }
            school {
                name
            }
        }
    }"""

    variables = {'$a': 'Alice'}
    res = client.txn(read_only=True).query(query, variables=variables)
    ppl = json.loads(res.json)

    # Print results.
    print('Number of people named "Alice": {}'.format(len(ppl['all'])))
    return ppl

查詢并添加數(shù)據(jù)

query = """{
  u as var(func: eq(name, "Alice"))
}"""
nquad = """
  uid(u) <name> "Alice" .
  uid(u) <age> "25" .
  <_:tom> <name> "Tom" .
  uid(u) <boyfriend> <_:tom> (love=1) .
"""
txn = client.txn()
mutation = txn.create_mutation(set_nquads=nquad)
request = txn.create_request(query=query, mutations=[mutation], commit_now=True)
txn.do_request(request)