DeepCopy? CMake?

[ArtemGr]

Hi, Philipp!

Would you mind accepting a pull request of this patch
https://github.com/scanlime/rapidjson/commit/0c69df5ac098640018d9232ae71ed1036c692187 ?

Also, what do you think of Git and CMake patches at https://github.com/rjeczalik/rapidjson ? Would it be feasible to integrate these in order to have both your fixes and Git submodules and CMake?

[pah]

Thanks for your suggestions (and for mentioning this fork in the upstream issue tracker).
In general, I'm not happy with the current proliferation of source repositories, although I didn't help by forking myself. ;-)

Would you mind accepting a pull request of this patch scanlime/rapidjson@0c69df5 ?

I'm not sure. In general, deep-copying is a valuable addition, but I don't like the API of this proposal. A couple of weeks ago, I have built a similar solution which I didn't publish on GitHub so far.

I have now pushed it and opened the pull-request #2 for it. What do you think? Adding a DeepCopy function to GenericDocument to follow the patch in scanlime/rapidjson@0c69df5 would be possible.

@scanlime, what do you think? Is there an upstream issue reported for this?

Also, what do you think of Git and CMake patches at https://github.com/rjeczalik/rapidjson ?
Would it be feasible to integrate these in order to have both your fixes and Git submodules and CMake?

I would certainly accept and merge the Cmake integration. Although I don't use the Rapidjson build infrastructure at all (instead maintain the Rapidjson sources directly within our projects), this may be useful for some people.

I can see the value of the Git submodules approach, but I want to follow upstream on this (see svn/trunk branch). I would accept patches to update the thirdparty sources, though.

[ArtemGr]

Your version of DeepCopy looks good!
Seen your other Tencent/rapidjson#1. Much appreciated. Wasn't aware that Milo had a repository here.

CMake integration isn't as important as I've initially thought, because it's mostly used to build the unit tests. With your Tencent/rapidjson#1 I'd rather wait for Milo reaction.

[michcleary]

Is this DeepCopy in rapidjson version 1.1.0? Is there a good example of it? Otherwise I might just use http://stackoverflow.com/questions/22707814/perform-a-copy-of-document-object-of-rapidjson the copyDocument comment/answer.

[pah]

Yes, all of the changes in this repository are upstreamed by now. DeepCopy is called CopyFrom in the upstream API:

You can find the CopyFrom documentation here and an example in the tutorial.

[michcleary]

CopyFrom doesn't look like a good solution for getting a deep copy to me.  I'd have to iterate over my entire (very large) json, store each value separately into a new value object, then use copyFrom.  The example you show is overly simplified.   It might be easier to just re-parse it. Yes, all of the changes in this repository are upstreamed by now. DeepCopy is called CopyFrom in the upstream API:You can find the CopyFrom documentation here and an example in the tutorial.— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[pah]

CopyFrom already does the traversal, as does the explicit copy constructor (which requires an allocator for the allocation of the string and value copies).

Just use something like

Document src;
src.Parse(...);

Document dst;
dst.CopyFrom(src, dst.GetAllocator());
// dst holds the same values (recursively) as src

Submitted upstream by myself as Tencent/rapidjson#20.

[michcleary]

Thank you so much!!  I hadn't realized that.  It's much better than the copy/re-parse thing I was doing. CopyFrom already does the traversal, as does the explicit copy constructor (which requires an allocator for the allocation of the string and value copies).Just use something likeDocument src; src.Parse(...); Document dst; dst.CopyFrom(src, dst.GetAllocator()); // dst holds the same values (recursively) as srcSubmitted upstream by myself as Tencent/rapidjson#202.— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[michcleary]

I'm not sure if you would have time to answer another rapidjson question. I'm trying to retrieve nested json values like they show in the rapidjson tutorial link.  The only way I can do that is by using a string buffer, but that doesn't really return what the value of m_x is, it just returns the contents of m_position, which is a string (not good use of json to get value).   My json looks like this:{ "type": "SlxROI", "m_position": { "m_x": 16, "m_y": 32, "m_z": 0 }, "m_size": { "m_widt h ":64," m_height ":128," m_depth ":3}} This is what it looks like as a c string:static const std::string& JSON2()    {        static const std::string j =            "{\"type\":\"SlxROI\",\"m_position\":{\"m_x\":16,\"m_y\":32,\"m_z\":0},\"m_size\":{\"m_width\":64,\"m_height\":128,\"m_depth\":3}}";        return j;    } I know it's valid because it doesn't return an error when I parse it. rapidjson::StringStream strStream(JSON2().c_str());rapidjson::Document origDocument; rapidjson::ParseResult result = origDocument.ParseStream(strStream); assert(newDocument.IsObject());rapidjson::StringBuffer sb;rapidjson::Writer<rapidjson::StringBuffer> writer (sb);newDocument["m_position"].Accept(writer);std::string temp  = sb.GetString(); //this works and I see the nested part inside m_position, but I'm not sure how to retrieve m_x from this without putting the buffer into a rapidjson document  //it would be better to retrieve specific value in nested json but it's not workingrapidjson::Value& mpos = newDocument["m_position"];assert(mpos.IsArray()); //this doesn't work (asserts), but this is what people do in what I'm seeing online....shouldn't it?assert(newDocument.HasMember("m_x")); //this doesn't work either...assert How can I retrieve the nested value?  All examples I'm seeing aren't working, and I'm assuming it's because of that rapidjson_disableif_return, although it does seem to be showing a bad pointer (n).   I was looking at this example (Tencent/rapidjson#336), but what they are discussing doesn't seem to work, when trying to retrieve specific things (see above):Value& parameterB = document["parameterB"]; assert(parameterB.IsArray()); I was looking at this too (http://stackoverflow.com/questions/40816266/rapidjson-how-to-receive-member-object-when-using-findmember)but for me, it doesn't seem to be the case:rapidjson::Pointer keyPointer("m_position");if(newDocument.IsArray()) { //it's not an array so doesn't fall in here        for(rapidjson::SizeType i=0; i<newDocument.Size(); i++) {            if (rapidjson::Value* m_pos = keyPointer.Get(newDocument[i])) {                assert(m_pos->HasMember("m_x"));            }        }} I'm not seeing how to retrieve the value of the nested item.  I can't get it to work no matter what I try.  Any help would be greatly appreciated. Thank you very much. CopyFrom already does the traversal, as does the explicit copy constructor (which requires an allocator for the allocation of the string and value copies).Just use something likeDocument src; src.Parse(...); Document dst; dst.CopyFrom(src, dst.GetAllocator()); // dst holds the same values (recursively) as srcSubmitted upstream by myself as Tencent/rapidjson#202.— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[pah]

Hi Michele,

I would appreciate if you could try adding some formatting to your answer. It's very hard to parse it here.

Starting from your original JSON:

{ 
  "type": "SlxROI",
  "m_position": { "m_x": 16, "m_y": 32, "m_z": 0 },
  "m_size": { "m_width ":64," m_height ":128," m_depth ":3}
}

you can access the m_position member (assuming you know it's there), via

   using namespace rapidjson;
   Document origDocument; 
    // ...
   assert( origDocument.IsObject() && origDocument.HasMember("m_position");
   Value& m_pos = origDocument["m_position"];
   assert( m_pos.IsObject() );
   for (Value::ConstMemberIterator itr = m_pos.MemberBegin(); itr != m_pos.MemberEnd(); ++itr)
   {
        printf("Value of 'm_position' member '%s' is %u\n",
            itr->name.GetString(), itr->value.GetUint());
   }

Dereferencing the ConstMemberIterator returns a Member object, which essentially contains a name and a value element.

Hope that helps,
Philipp

[michcleary]

Thank you so much Philipp!!  That is very helpful.  Have a great weekend! Hi Michele,I would appreciate if you could try adding some formatting to your answer. It's very hard to parse it here.Starting from your original JSON:{ "type": "SlxROI", "m_position": { "m_x": 16, "m_y": 32, "m_z": 0 }, "m_size": { "m_width ":64," m_height ":128," m_depth ":3} }you can access the m_position member (assuming you know it's there), via using namespace rapidjson; Document origDocument; // ... assert( origDocument.IsObject() && origDocument.HasMember("m_position"); Value& m_pos = origDocument["m_position"]; assert( m_pos.IsObject() ); for (Value::ConstMemberIterator itr = m_pos.MemberBegin(); itr != m_pos.MemberEnd(); ++itr) { printf("Value of 'm_position' member '%s' is %u\n", itr->name.GetString(), itr->value.GetUint()); }Dereferencing the ConstMemberIterator returns a Member object, which essentially contains a name and a value element.Hope that helps, Philipp— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[michcleary]

Thanks a lot.  If I want to copy a node at this point and not a document, it looks like GetAllocator can't be used for that...Is there another way to copy a Value?  static void copyValue(rapidjson::Value & newNode,   const rapidjson::Value & originalNode)  {                 //better way to copy                std::cout << "SlxJson2Impl::copyValue...." << std::endl;                newNode.CopyFrom(originalNode, newNode.GetAllocator());  } CopyFrom already does the traversal, as does the explicit copy constructor (which requires an allocator for the allocation of the string and value copies).Just use something likeDocument src; src.Parse(...); Document dst; dst.CopyFrom(src, dst.GetAllocator()); // dst holds the same values (recursively) as srcSubmitted upstream by myself as Tencent/rapidjson#202.— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[michcleary]

By the way, I want to copy the Value without making a Document.  We are trying to keep the DOM concept out of our design for now (except for error checking) and just create Nodes/Values.  That would be great if you could let me know a good way to do this.  I'm sure you would have a copy concept for this like you do for the Document. Thanks a lot.  If I want to copy a node at this point and not a document, it looks like GetAllocator can't be used for that...Is there another way to copy a Value?  static void copyValue(rapidjson::Value & newNode,   const rapidjson::Value & originalNode)  {                 //better way to copy                std::cout << "SlxJson2Impl::copyValue...." << std::endl;                newNode.CopyFrom(originalNode, newNode.GetAllocator());  } CopyFrom already does the traversal, as does the explicit copy constructor (which requires an allocator for the allocation of the string and value copies).Just use something likeDocument src; src.Parse(...); Document dst; dst.CopyFrom(src, dst.GetAllocator()); // dst holds the same values (recursively) as srcSubmitted upstream by myself as Tencent/rapidjson#202.— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[pah]

By the way, I want to copy the Value without making a Document. We are trying to keep the DOM concept out of our design for now (except for error checking) and just create Nodes/Values. That would be great if you could let me know a good way to do this. I'm sure you would have a copy concept for this like you do for the Document.

You can't have a Value without an Allocator. With an Allocator, you can use the same concept even without a Document. A Document is more or less just a combination of an allocator and a (root) Value.