Cosmos-sdk: sdk.Dec JSON Marshal to String()

[faboweb]

Summary of Bug

sdk.Dec of the value 1000 marshalls to a string representation 1000000000000. 1000000000000 is an internal precision representation. The marshalled value should be 1000.000000000.

Steps to Reproduce

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[alexanderbez]

One thing to note is that if we go with marshalling using String() we'll probably need to use NewDecFromStr() which has a bigger performance hit than simply using big int's MarshalText/UnmarshalText.

[cwgoes]

I don't really agree, why would we add a decimal?

In JSON that might lead to reduced precision due to floating-point arithmetic.

Perhaps the LCD should expose the constant precision factor via API to enable frontends to convert easily.

[ValarDragon]

There's two encodings here, JSON and amino. This proposal is basically asking about switching from encoding the number directly to instead encode the number as a string / bytes. I have no problem with marshalling as a string with the decimal in JSON. That seems like a much better approach. This then improves the clarity, and ease of integrating. There is no fear of floating point arithmetic, as it would encoded as a string essentially.

For amino I don't think we should do this. Part of the efficiency of protobuf is that you know the type at the field, so you don't have to do stuff like this.

[rigelrozanski]

Yeah, I'm pretty sure we can marshal differently for json/amino - we should totally marshal json decimal to a string 👍

[cwgoes]

Marshaling to a string with a decimal is fine but is that what @faboweb is asking for?

[ValarDragon]

I guess there were two ways to interpet marshal as string, marshalling to the string type, and marshalling to the string representation (with the decimal point). I actually meant both in my comment, but I should've clarified. I believe fabo is asking for both as well.

[faboweb]

I am only asking for marshalling to string not amino.

[ValarDragon]

FYI were switching to ints here once fee distribution is merged, so this shouldn't be a problem. I still agree with changing this anyway though, as it will be needed when handling stuff for fee distribution.

[faboweb]

Nice!