GH-43 Adds support for serialization of amount number as string

[AlexanderYastrebov]

Fixes #43

[whiskeysierra]

Needs some readme change.

[whiskeysierra]

Why?

[whiskeysierra]

Instead of using a boolean, can we use our own implementation of Jackson's Feature types?

[AlexanderYastrebov]

I initially implemented features the same way as jackson does, but then discarded it since I hope there will not be that many toggles at all

[whiskeysierra]

I'd still prefer a Feature enum.

[AlexanderYastrebov]

Do you mean own or Jackson's? With Jackson's we have to fail if someone requests other feature beside WRITE_NUMBERS_AS_STRINGS

[whiskeysierra]

We could implement ConfigFeature ourselves, but I think what would be a better fit would be an enum:

public enum Style {
    DECIMAL, STRING
}

[whiskeysierra]

I just found this: http://fasterxml.github.io/jackson-core/javadoc/2.8/com/fasterxml/jackson/core/JsonGenerator.Feature.html#WRITE_NUMBERS_AS_STRINGS

Feature that forces all Java numbers to be written as JSON strings. Default state is 'false', meaning that Java numbers are to be serialized using basic numeric serialization (as JSON numbers, integral or floating point). If enabled, all such numeric values are instead written out as JSON Strings.
One use case is to avoid problems with Javascript limitations: since Javascript standard specifies that all number handling should be done using 64-bit IEEE 754 floating point values, result being that some 64-bit integer values can not be accurately represent (as mantissa is only 51 bit wide).

Feature is disabled by default.

[AlexanderYastrebov]

I just found this

I have seen it.
It changes behavior for all numbers and we want only number-as-string within monetary amount.

[AlexanderYastrebov]

@whiskeysierra RFC

[whiskeysierra]

It changes behavior for all numbers and we want only number-as-string within monetary amount.

True, but client at least have an option right now already.

[AlexanderYastrebov]

@whiskeysierra I dont get your point, could you explain?

[whiskeysierra]

If somebody want to use strings instead of decimal number he/she can already use Jackson's built-in support for that (they might be ok with all numbers being strings).

[AlexanderYastrebov]

Ah, so you want default value to be inherited from that configured jackson feature?

[whiskeysierra]

Once WRITE_NUMBERS_AS_STRINGS is enabled it will overrule anything in this PR.

[AlexanderYastrebov]

Once WRITE_NUMBERS_AS_STRINGS is enabled it will overrule anything in this PR.

And this is desired, isnt it?

[AlexanderYastrebov]

Or do you want to say this feature is not needed at all?
The value is that it allows to serialize as strings only monetary amounts and leave other numerals intact

[whiskeysierra]

Or do you want to say this feature is not needed at all?

Well, I'm ambivalent. On the one hand I'd say it's not needed since Jackson kind of already supports it.

The value is that it allows to serialize as strings only monetary amounts and leave other numerals intact

On the other hand I see the value in that. That feature however could be understood in a more general concept: It would be nice to enable/disable certain features for certain types/subtypes/object graphs/...

It does not apply to monetary amounts alone, but could be useful to others as well. No idea how to tackle this, though.

[AlexanderYastrebov]

After some consideration we decided to implement it as an pluggable interface instead of feature toggle.
I will update PR.

[AlexanderYastrebov]

Closing in favor of #48