rapidjson - change key to another value

Question

Here is the hello world of rapidjson. How can I change key "hello" to "goodbye" and get string from the json? I mean I want to parse json, change some keys and get json string back like {"goodbye" : "world"}.

const char json[] = "{ \"hello\" : \"world\" }";

rapidjson::Document d;
d.Parse<0>(json);

ArtemGr · Accepted Answer · 2014-06-16T14:05:22.570

8

  const char *json = R"({"hello": "world"})";
  rapidjson::Document d;
  d.Parse<0> (json);

  rapidjson::Value::Member* hello = d.FindMember ("hello"); if (hello) {
    d.AddMember ("goodbye", hello->value, d.GetAllocator());
    d.RemoveMember ("hello");
  }

  typedef rapidjson::GenericStringBuffer<rapidjson::UTF8<>, rapidjson::MemoryPoolAllocator<>> StringBuffer;
  StringBuffer buf (&d.GetAllocator());
  rapidjson::Writer<StringBuffer> writer (buf, &d.GetAllocator());
  d.Accept (writer);
  json = buf.GetString();

P.S. You should probably copy the json afterwards because its memory will be freed together with d.

P.P.S. You can also replace the field name in-place, without removing it:

rapidjson::Value::Member* hello = d.FindMember ("hello");
if (hello) hello->name.SetString ("goodbye", d.GetAllocator());

Or during iteration:

for (auto it = d.MemberBegin(); it != d.MemberEnd(); ++it)
  if (strcmp (it->name.GetString(), "hello") == 0) it->name.SetString ("goodbye", d.GetAllocator());

edited Jun 16 '14 at 14:05

answered Jun 13 '14 at 15:59

ArtemGr

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What if I iterated and found the member already. I just need to rename the key. – Narek Jun 16 '14 at 06:43
Updated with in-place examples. – ArtemGr Jun 16 '14 at 14:06
you use Rapidjson 0.2 right as you have a public `FindMember` method. Where I can find the code for it? – Narek Mar 24 '15 at 07:24
@Narek, I'm using this repo: https://github.com/miloyip/rapidjson. It's been long since I last updated, but from what I see at https://github.com/miloyip/rapidjson/blob/master/include/rapidjson/document.h the `FindMember` still seems to be public. What version are you using? – ArtemGr Mar 24 '15 at 08:28
the one that comes with cocos2d-x latest version which should be 0.11 where `FindMember` is not a public method. – Narek Mar 24 '15 at 09:37

score 2 · Answer 2 · edited Jun 17 '14 at 11:40

2

In my case there is a key dictionary named keyDict which stores the values that object keys should be replaced with.

std::string line;
std::map<std::string, int>  keyDict;

.....................
.........................

rapidjson::Document         doc;
doc.Parse<0>(line.c_str());
rapidjson::Value::MemberIterator itr;


for (itr = doc.MemberonBegin(); itr != doc.MemberonEnd(); ++itr)
{
    std::string keyCode = std::to_string(keyDict[itr->name.GetString()]);
    itr->name.SetString(keyCode.c_str(), keyCode.size(), doc.GetAllocator());
}

edited Jun 17 '14 at 11:40

ArtemGr

11,684
3
52
85

answered Jun 16 '14 at 06:51

Narek

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It is a question. I have asked, you answered me, but then I have figured out this way, and wanted to check if it is OK or not. Thanks for you answeres. – Narek Jun 16 '14 at 16:55
@dasblinkenlight as you could note my answer is a complete answer too. And I undeleted my post as far I have a case ArtemGr does not. I mean when you set string using not literals, but local variable. – Narek Jun 16 '14 at 16:57

rapidjson - change key to another value

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