使用jsoncpp遍历JSON对象数组 [英] Iterate over an array of JSON objects with jsoncpp

问题描述

我有以下类型的JSON对象数组，jsonArr说:

I have an array of JSON objects, jsonArr say, of the following kind:

[
  { "attr1" : "somevalue",
    "attr2" : "someothervalue"
  },
  { "attr1" : "yetanothervalue",
    "attr2" : "andsoon"
  },
  ...
]

我使用jsoncpp尝试遍历数组，并检查每个对象是否都有成员"attr1"，在这种情况下，我想将相应的值存储在向量values中.

Using jsoncpp, I'm trying to iterate through the array and check whether each object has a member "attr1", in which case I would like to store the corresponding value in the vector values.

我尝试过类似的事情

Json::Value root;
Json::Reader reader;
Json::FastWriter fastWriter;
reader.parse(jsonArr, root);

std::vector<std::string> values;

for (Json::Value::iterator it=root.begin(); it!=root.end(); ++it) {
  if (it->isMember(std::string("attr1"))) {
    values.push_back(fastWriter.write((*it)["uuid"]));
  }
}

但不断收到错误消息

libc++abi.dylib: terminating with uncaught exception of type Json::LogicError: in Json::Value::find(key, end, found): requires objectValue or nullValue

推荐答案

很容易解释:

for (Json::Value::ArrayIndex i = 0; i != root.size(); i++)
    if (root[i].isMember("attr1"))
        values.push_back(root[i]["attr1"].asString());

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