Steps to replicate the issue (include links if applicable):
- Install ArrayFunctions
- Create the following Lua module:
local p = {}
function p.example()
local json = '["a", "b", "c", "d", "e", "f", "g", "h"]';
local arr = mw.text.jsonDecode(json);
return mw.af.export(arr);
end
return p- Observe the result of invoking this module:
What happens?:
The order of the table is random.
What should have happened instead?:
The order of the table is preserved.
Software version (skip for WMF-hosted wikis like Wikipedia):
MediaWiki: 1.39.4
Lua: 5.1.5 (standalone)
Other information (browser name/version, screenshots, etc.):
This seems to happen because pairs (as opposed to ipairs) is used in the MWServer:serialize function. Looping over the table using pairs in Lua directly shows this:
local p = {}
function p.example()
local json = '["a", "b", "c", "d", "e", "f", "g", "h"]';
local arr = mw.text.jsonDecode(json);
for k, v in pairs(arr) do
mw.log(k, v);
end
end
return p6 f 2 b 8 h 3 c 1 a 4 d 5 e 7 g
Using ipairs gives the correct (ordered) result. Interestingly, building a new table from the old one fixes the problem:
local p = {}
function p.test()
local json = '["a", "b", "c", "d", "e", "f", "g", "h"]';
local arr = mw.text.jsonDecode(json);
local new_arr = {};
for k, v in pairs(arr) do
new_arr[k] = v;
end
for k, v in pairs(new_arr) do
mw.log(k, v)
end
end
return p1 a 2 b 3 c 4 d 5 e 6 f 7 g 8 h