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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 (21 comments) (7 reactions) (0 assignees)C++ (2,602 forks)batch import
enhancementhelp wanted

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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

Research direction
Investigate the internal representation of Json::Value objects. The current implementation uses an ordered map (likely std::map) for object members, which sorts keys alphabetically. To preserve insertion order, you need to replace the container with one that maintains insertion order, such as a vector of key value pairs or a custom ordered map. Study the Value class layout and the methods for adding/iterating members.
Tech stack
cpp
Domain
apibackend
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.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++JSON
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65