Access specific fields in json file (C++)

Asked Apr 05 '18 at 06:56

Active Apr 05 '18 at 07:42

Viewed 107 times

char c;
std::cout<<"Hello World";
std::ifstream people_file("query.json");
while(people_file.get(c)){
    std::cout<<c;
}

This is my code, tho I am able to print whole json file. But I don't know how to access specific columns in it. Under given is a snapshot of the .json file.Suppose I want to access "_id" and "duration" fields.

asked Apr 05 '18 at 06:56

Lieutenant. X

Are you using MongoDB – Xay Apr 05 '18 at 06:57
FYI: that isn't a proper JSON formatted file. Anyway, you need to _parse_ it. – Aluan Haddad Apr 05 '18 at 06:57
1

Try to use a JSON parsing library instead of doing it all yourself. Parsing and handling JSON is far from trivial, and there are already libraries which will handle all the tricky bits for you. – Some programmer dude Apr 05 '18 at 06:57
@AkshayRohilla yes, MongoDB – Lieutenant. X Apr 05 '18 at 06:58
@AluanHaddad I have exported this file from mongo, haven't made any changes in it. So, it should be a json file. – Lieutenant. X Apr 05 '18 at 06:59
This might help you https://stackoverflow.com/questions/31121378/json-cpp-how-to-initialize-from-string-and-get-string-value – Gaurav Apr 05 '18 at 06:59
@Someprogrammerdude Just guide me, how to do it. I am new to using json with C++ – Lieutenant. X Apr 05 '18 at 06:59
@Lieutenant.X no. It is a MongoDB formatted file. A standard JSON parser will fail to parse it. – Aluan Haddad Apr 05 '18 at 07:00
@AluanHaddad I have to use this file for my work, any suggestions. How my problem can be solved if other stuffs can be used? – Lieutenant. X Apr 05 '18 at 07:02
You need to have Mongo output something else or you need to transform it. For example you can quote all of the non-JSON values like changing `NumberInt(18)` to `"NumberInt(18)"` – Aluan Haddad Apr 05 '18 at 07:03
@AluanHaddad I can even use csv, tell me which file would be easy to read and parse in C++ – Lieutenant. X Apr 05 '18 at 07:09

Access specific fields in json file (C++)

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