cjson.encode() modified order

[yhc19850706]

when i use cjson.encode(table), the table is modified order ,why? e.g: local json = cjson.encode({name="yhc",age=40,birthday="1985"})

print(json) -- {"birthday":"1985","name":"yhc","age":40}

i don't want to change,how to do?

[dannygueta]

Hi,

same problem here, any lead ?

Thanks.

[libing0526]

I hava the same problem，anybody knows why？

[doujiang24]

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.

[travisbell]

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.

[libing0526]

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

[libing0526]

https://plain.blog.csdn.net/article/details/120364853 it seems like a good method

[edo888]

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"}