AppendJson is a bit misleading

[liamsi]

While it sounds like it will append to the end, it uses a golang map internally. Hence, the passed key won't necessarily end up at the end (and the written JSON can have a completely different key ordering):

cosmos-sdk/server/util.go

Lines 126 to 136 in 270e216

	// append a new json field to existing json message
	func AppendJSON(cdc *wire.Codec, baseJSON []byte, key string, value json.RawMessage) (appended []byte, err error) {
	var jsonMap map[string]json.RawMessage
	err = cdc.UnmarshalJSON(baseJSON, &jsonMap)
	if err != nil {
	return nil, err
	}
	jsonMap[key] = value
	bz, err := wire.MarshalJSONIndent(cdc, jsonMap)
	return json.RawMessage(bz), err
	}

This might causes some confusion. Suggestions: either InsertKeyAndSortJSON (sort keys after including the new key) , or, IncludeJSON (keeps the introduced non-determinism but is clearly named).

See also:
tendermint/go-amino#171 (comment)
#983 (comment)

[alexanderbez]

Ahhh confusing indeed! I think we could have both solutions you suggested actually and leave it up to the client to choose which it wants 👍

[alexanderbez]

I'll address this in #983 :-)

[liamsi]

Just to make sure we won't do double the work: I'm currently adding a method that takes arbitary JSON and returns (semantically) the same JSON but sorted by keys.

[alexanderbez]

@liamsi perfect, I won't implement the sorted variant, I'll just rename the existing function. Also, fun fact, json.Marshal already sorts by keys, but I'm not sure how amino does it.

[liamsi]

I know, my idea was to take arbitrary json, decode into an interface{} and call json.Marshal. I still need to do some tests though: https://github.com/cosmos/cosmos-sdk/compare/develop...Liamsi:sorted_json?expand=1#diff-44da3d359afd2823a31e4fb048bdfdf4R142 (also we don't want the json to be indented by default)

Amino doesn't by key (like proto3 doesn't sort field names either; although map keys are sorted by proto3 IIRC).

[alexanderbez]

Closed via #1559