cjson.encode() modified order #66

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1. dannygueta commented on Mar 1, 2021

   

   dannygueta

   on Mar 1, 2021

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   Hi,

   same problem here, any lead ?

   Thanks.
2. libing0526 commented on Sep 10, 2021

   

   libing0526

   on Sep 10, 2021

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   I hava the same problem，anybody knows why？
3. doujiang24 commented on Sep 10, 2021

   

   doujiang24

   on Sep 10, 2021

   Member

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   cjson.encode can not have the fixed order since Lua table doesn't have a fixed order for keys.
   otherwise, cjson.encode have to sort for the keys, it will hit bad performance then.
4. travisbell commented on Sep 10, 2021

   

   travisbell

   on Sep 10, 2021

   Last edited by travisbell

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   There is a PR on the original mpx/lua-cjson repo here, that adds support for this. It only took a few small tweaks to get working with the latest openresty/lua-cjson. I have a working branch of this here.

   Just configure OpenResty with the --without-lua_cjson flag, and then you can just build and require your own custom cjson (I'm using LuaRocks for this) in your project. I've been using this in production for almost a year with no problems. Performance is still great.
5. libing0526 commented on Sep 13, 2021

   

   libing0526

   on Sep 13, 2021

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   There is a PR on the original mpx/lua-cjson repo here, that adds support for this. It only took a few small tweaks to get working with the latest openresty/lua-cjson. I have a working branch of this here.

   Just configure OpenResty with the --without-lua_cjson flag, and then you can just build and require your own custom cjson (I'm using LuaRocks for this) in your project. I've been using this in production for almost a year with no problems. Performance is still great.

   This is a good method, but it seems that it can only be applied to a small amount of data. The number of citations Lua stack is limited to 20
6. libing0526 commented on Sep 24, 2021

   

   libing0526

   on Sep 24, 2021

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   https://plain.blog.csdn.net/article/details/120364853
   it seems like a good method
7. edo888 commented on Apr 16, 2022

   

   edo888

   on Apr 16, 2022

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   You can possibly define the order you want in __order metatable and use the forked version: https://github.com/edo888/lua-cjson

   local cjson = require "cjson.safe"
   cjson.decode_save_key_order(true)
   
   local json = {name="yhc",age=40,birthday="1985"}
   setmetatable(json, {
       __order = {"name", "age", "birthday"}
   })
   print(cjson.encode(json))
   

   Output:

   {"name":"yhc","age":40,"birthday":"1985"}
8. arkriny

   added a commit that references this issue on Sep 20, 2025

   feature: add option to sort encoded object keys

   ...

   This issue will close once commit 7819ac4 is merged into the 'master' branch.

   7819ac4
9. arkriny

   added a commit that references this issue on Feb 9, 2026

   feature: add option to sort encoded object keys

   ...

   This issue will close once commit f945fde is merged into the 'master' branch.

   f945fde
10. zhuizhuhaomeng

    closed this as completedin #115on Sep 6, 2026