java - Java 中的 Dgraph。如何运行原始字符串变异查询？

Question

我需要能够在不使用 newBuilder() 的情况下运行原始字符串突变查询:

Gson gson = new Gson();
String json = gson.toJson(newEmployer);
Transaction newTransaction = this.dgraphClient.newTransaction();
Mutation mu = Mutation.newBuilder().setSetJson(ByteString.copyFromUtf8(json.toString())).build();
newTransaction.mutate(mu);

我想运行:

String email = "ba@a.aa";
String userType = "JOB_SEEKER";
Transaction newTransaction = this.dgraphClient.newTransaction();
String query = 
        "{\n" +
        "    set { \n" +
        "       _:user <label> \"USER\" . \n" +
        "      _:user <userType> \"" + email + "\" . \n" +
        "      _:user <email> \"" + userType + "\" . \n" +
        "    }\n" +
        "}";
Mutation mu = Mutation.parseFrom(ByteString.copyFromUtf8(query));
newTransaction.mutate(mu);

但是我在运行时收到错误:“在解析协议(protocol)消息时，输入在字段中间意外结束。这可能意味着输入已被截断，或者嵌入式消息误报了自己的长度”

Answer 1

在 gRPC 客户端(例如 dgraph4j)中为突变设置 N-Quad 三元组时，您只需指定换行符分隔的三元组本身并将它们传递给 Mutation#setSetNquads。它们没有被 set 包围。换句话说，而不是这个:

{
  set {
    _:user <label> "USER" .
    _:user <userType> "USER_TYPE" .
    _:user <email> "ba@a.aa" .
  }
}

您只需要三元组:

_:user <label> "USER" .
_:user <userType> "USER_TYPE" .
_:user <email> "ba@a.aa" .

它在 Java 代码中的样子如下:

String email = "ba@a.aa";
String userType = "JOB_SEEKER";
Transaction newTransaction = this.dgraphClient.newTransaction();
String triples = 
        "_:user <label> \"USER\" .\n" +
        "_:user <userType> \"" + email + "\" .\n" +
        "_:user <email> \"" + userType + "\" .";
Mutation mu =
    Mutation.newBuilder()
        .setSetNquads(ByteString.copyFromUtf8(triples))
        .build();
Assigned assigned = newTransaction.mutate(mu);

第一个带有 { set { ... } } 的突变格式适用于 HTTP 客户端，其中包括 Dgraph Ratel 内的突变或带有 curl 的突变。

有关 Dgraph 突变的更多信息可在突变文档中找到:https://docs.dgraph.io/mutations/