jsoncpp。通过匹配值在数组中查找对象 [英] jsoncpp. find object in array by matching value
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问题描述
我有这个JSON对象:
I have this JSON object:
{"books":[
{
"author" : "Petr",
"book_name" : "Test1",
"pages" : 200,
"year" : 2002
},
{
"author" : "Petr",
"book_name" : "Test2",
"pages" : 0,
"year" : 0
},
{
"author" : "STO",
"book_name" : "Rocks",
"pages" : 100,
"year" : 2002
}
]
}
例如,我需要找一本书) author
键等于 Petr
。我如何做到这一点?现在我有这段代码:
For example, I need to find a book(s) which author
key is equal to Petr
. How can I do this? Right now I have this piece of code:
Json::Value findBook(){
Json::Value root = getRoot();
cout<<root["books"].toStyledString()<<endl; //Prints JSON array of books mentioned above
string searchKey;
cout<<"Enter search key: ";
cin>>searchKey;
string searchValue;
cout<<"Enter search value: ";
cin>>searchValue;
Json::Value foundBooks = root["books"]???; // How can I get here a list of books where searchKey is equal to searchValue?
}
提前感谢。
推荐答案
这样的操作应该是:
std::vector<Json::Value> booksByPeter(const Json::Value& root) {
std::vector<Json::Value> res;
for (const Json::Value& book : root["books"]) // iterate over "books"
{
if (book["author"].asString() == "Petr") // if by "Petr"
{
res.push_back(book); // take a copy
}
}
return res; // and return
}
如果不是C ++ 11, :
If not C++11, will instead have to do:
const Json::Value& books = root["books"];
for (Json::ValueConstIterator it = books.begin(); it != books.end(); ++it)
{
const Json::Value& book = *it;
// rest as before
}
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