多值屬性

• Gremlin語法中對頂點提供了多值屬性支持，在添加或者更新屬性時可以通過cardinality參數指定屬性的類型。

• Gremlin提供了兩種類型的多值屬性：set和list。GDB從1.0.20版本開始支持set屬性。

注意事項

• 只有頂點支持多值屬性，邊不支持。

• 一個set屬性的多個value可以是不同類型，但是GDB在判斷值是否相同時是按照語義進行比較的，類型不同但是值相等的兩個value會被認為是相同的（例如1和1.0），因而只會保留一個。

• 屬性的cardinality可以改變，以最后一次調用property()更新屬性為準。set屬性更新為single類型后，只保留后者的值；single屬性更新為set類型后，前后兩個值都保留。

• set屬性查詢結果中的多個值是按照語義排序的。如果是數值型，按值升序排列；如果是字符串型，按字典序排列。

• set屬性和single屬性一樣，會自動建立索引，查詢性能跟single屬性相近。

Set屬性用法

_Console

• 設置屬性

  g.addV('person').
  property(id, '11111').
  property('name', 'marko').
  property(set, 'email', 'marko@a.com').
  property(set, 'email', 'marko@b.com')

• 查詢屬性

  g.V('11111').properties('email')
  ==>vp[email->marko@a.com]
  ==>vp[email->marko@b.com]

• 刪除一個值

  g.V('11111').properties('email').hasValue('marko@a.com').drop()

• 刪除所有值

  g.V('11111').properties('email').drop()

_Java

package com.gdb.alibaba;

import org.apache.tinkerpop.gremlin.driver.Cluster;
import org.apache.tinkerpop.gremlin.driver.Client;
import org.apache.tinkerpop.gremlin.driver.Result;
import org.apache.tinkerpop.gremlin.driver.ResultSet;
import org.apache.tinkerpop.gremlin.structure.util.detached.DetachedVertex;
import org.apache.tinkerpop.gremlin.structure.util.detached.DetachedVertexProperty;

import java.util.List;
import java.util.Map;
import java.util.HashMap;
import java.io.File;

public class Test {
  public static void main(String[] args) {
    try {
      if (args.length != 1) {
        System.out.println("gdb-remote.yaml path needed");
        return;
      }
      String yaml = args[0];
      Cluster cluster = Cluster.build(new File(yaml)).create();
      Client client = cluster.connect().init();
      String dsl = "g.addV(yourLabel).property(propertyKey, propertyValue).property(set, setPropertyKey, setPropertyValue0).property(set, setPropertyKey, setPropertyValue1)";
      Map<String, Object> parameters = new HashMap<>();
      parameters.put("yourLabel", "person");
      parameters.put("propertyKey", "name");
      parameters.put("propertyValue", "marko");
      parameters.put("setPropertyKey", "email");
      parameters.put("setPropertyValue0", "marko@a.com");
      parameters.put("setPropertyValue1", "marko@b.com");
      ResultSet results = client.submit(dsl, parameters);
      List<Result> result = results.all().join();
      if (result.size() > 0) {
        String vertexId = (String) ((DetachedVertex) result.get(0).getObject()).id();
        parameters.put("yourId", vertexId);
      }

      dsl = "g.V(yourId).properties(setPropertyKey)";
      results = client.submit(dsl, parameters);
      result = results.all().join();
      result.forEach(r -> {
        Object element = r.getObject();
        if (element instanceof DetachedVertexProperty) {
          DetachedVertexProperty property = (DetachedVertexProperty) element;
          System.out.println(property.key() + ": " + property.value());
        }
      });

      cluster.close();
    } catch (Exception e) {
      System.out.println(e.getMessage());
    }
  }
}

_Python

• 用法1：

  from gremlin_python.process.anonymous_traversal import traversal
  from gremlin_python.driver.driver_remote_connection import DriverRemoteConnection
  from gremlin_python.process.traversal import T, Cardinality
  
  g = traversal().withRemote(
      DriverRemoteConnection('ws://HOST:PORT/gremlin',
                             'g',
                             username=USER,
                             password=PASS))
  
  v = g.addV('person').property(T.id_, "123").property("name", "marko") \
      .property(Cardinality.set_, "email", "marko@gmail.com") \
      .property(Cardinality.set_, "email", "marko@hotmail.com").iterate()
  
  properties = g.V('123').properties('email')
  for prop in properties:
      print(prop.key + ": " + str(prop.value))
  
  g.V('123').drop().iterate()

• 用法2：

  from gremlin_python.driver import client
  
  client = client.Client('ws://HOST:PORT/gremlin',
                         'g',
                         username=USER,
                         password=PASS)
  
  dsl = 'g.addV("person").property(id, "123").property("name", "marko").property(set, "email", "marko@a.com").property(set, "email", "marko@b.com")'
  callback = client.submitAsync(dsl)
  for result in callback.result():
      print(result)
  
  dsl = 'g.V("123").properties("email")'
  callback = client.submitAsync(dsl)
  for result in callback.result():
      for prop in result:
          print(prop.key + ": " + str(prop.value))

_Go

    bindings := make(map[string]interface{})
    bindings["GDB___id"] = "22"
    bindings["GDB___label"] = "goTest"
    bindings["GDB___PK"] = "name"
    bindings["GDB___PV"] = "Jack"
    bindings["GDB___PK_PHONE"] = "phone"
    bindings["GDB___PV_PHONE1"] = "111111"
    bindings["GDB___PV_PHONE2"] = "222222"

    dsl := "g.addV(GDB___label).property(id, GDB___id).property(GDB___PK, GDB___PV).property(set, GDB___PK_PHONE, GDB___PV_PHONE1).property(set, GDB___PK_PHONE, GDB___PV_PHONE2)"
    results, err := client.SubmitScriptBound(dsl, bindings)
    if err != nil {
        log.Fatalf("Error while querying: %s\n", err.Error())
    }

    // get response, add vertex should return a Vertex
    for _, result := range results {
        v := result.GetVertex()
        log.Printf("get vertex: %s", v.String())

        // read vertex property
        for _, p := range v.VProperties() {
            log.Printf("prop: %s", p.String())
        }
    }

_Javascript

const gremlin = require('gremlin');
const DriverRemoteConnection = gremlin.driver.DriverRemoteConnection;
const Graph = gremlin.structure.Graph;
const __ = gremlin.process.statics;
const t = gremlin.process.t;
const cardinality = gremlin.process.cardinality
const authenticator =
    new gremlin.driver.auth.PlainTextSaslAuthenticator(USER, PASS);

const graph = new Graph();
const g = graph.traversal().withRemote(
    new DriverRemoteConnection('ws://HOST:PORT/gremlin', {authenticator}));

g.addV('person')
      .property(t.id, '2222')
      .property('name', 'james')
      .property(cardinality.set, 'phone', '111111')
      .property(cardinality.set, 'phone', '222222')
      .iterate()
      .then(data => {
        g.V('2222').properties().toList().then(
            properties => { console.log(properties); });
      });