Move back Precision to string type

[masci]

#179 Changed the type of Precision fields for various struct from *string to *json.Number but I can't make it work due to the fact that "*" is a valid value, meaning "full precision". Please notice acceptance tests don't expose the issue since Precision field for Widget (the one used in the tests) is still a string:

go-datadog-api/screen_widgets.go

Line 109 in ae3affd

Precision *string `json:"precision,omitempty"`

Not sure what was the rationale around #179 since it mentions the API might return int for precision sometimes but if that's the case we should fix the issue on the Datadog side, normalizing all the things to strings.

This is blocking an important fix for https://github.com/terraform-providers/terraform-provider-datadog/issues/117

[nyanshak]

I made a small playground link to demonstrate why it should be *json.Number rather than string: https://play.golang.org/p/6TAkg8WrJsg.

Namely, Datadog can return "precision": 1 (int) rather than "precision": "1" (string), which will cause errors with *string, but not *json.Number.

For that reason, I'm rejecting this change.

[masci]

@nyanshak try to add Precision: datadog.JsonNumber(json.Number("*")), to any TileDef in TestWidgets to expose the problem. Currently the integration tests don't exercise changes from #179.

Can you please keep this open for discussion, or should I move this to an issue? The current state of the client is half broken (in any case,

go-datadog-api/screen_widgets.go

Line 109 in ae3affd

Precision *string `json:"precision,omitempty"`

is still a *string).

[nyanshak]

I think you're right that Precision field in Widget being a different type than in TileDef isn't quite right. I have raised #194 to address it. Could you provide feedback there letting me know if that is sufficient?

[masci]

Superseded by #194