open-source-parsers/jsoncpp

Keep order of fields as they are added, not sorting alphabetically

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#1,202 opened on Jul 9, 2020

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enhancementhelp wanted

Description

To use json files in a context where human readability makes sense, order of the fields insertion can make sense. As jsoncpp is sorting them alphabetically, it becomes hard to read the file and find related fields in ddifferent ends of the object. For example Json::Value root; root["name"] = "Test;" root["host"] = "127.0.0.1"; root["port"] = 80;

would be nice to have printed as

{ "name" : "Test, "host" : "127.0.0.1", "port" : 80 }

and not as

{ "host" : "127.0.0.1", "name" : "Test, "port" : 80 }

I actually succeeded to have this feature by replacing a container used by Json::Value with a custom one.

Contributor guide

Tech stack
cpp
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++ knowledgejsoncpp internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Investigate the internal storage of Json::Value, likely currently using std::map which sorts keys alphabetically. The issue proposes replacing with an ordered container (e.g., std::vector of key value pairs or boost::container::flat map) to preserve insertion order. Review comments in issue #1202 for proposed implementations and potential performance trade offs. Key files to examine: include/json/value.h and src/lib json/json value.cpp.