Use exact capitalization from field names overridden in config

[ianling]

Closes #1447

Behavior prior to this PR: given the following schema and gqlgen config:

Schema:

type RenameFieldTest {
    badName: String!
    otherField: String!
}

gqlgen.yml:

models:
  RenameFieldTest:
    fields:
      badName:
        fieldName: GOODnaME

gqlgen generates the following Go struct:

type RenameFieldTest struct {
	GOODnaMe   string `json:"badName"`  // <----- field name should be GOODnaME, but e is lowercase
	OtherField string `json:"otherField"`
}

Behavior after this PR (modelgen strictly adheres to field names overridden in the config):

type RenameFieldTest struct {
	GOODnaME   string `json:"badName"` // <----- the 'e' is now correctly capitalized
	OtherField string `json:"otherField"`

Field names that are not overridden in the config will be exactly the same as before this PR, so users will only see different behavior if they had an overridden name that happened to fall into one of these funny capitalization edge cases.

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs) (not necessary)

[coveralls]

Coverage increased (+0.03%) to 75.157% when pulling 75e7089 on ianling:capitalization into 3a64078 on 99designs:master.

[StevenACoffman]

Thanks! Nice catch!

[carldunham]

So is this because of a bug in the go filter?

[ianling]

Nope, the go filter was just being erroneously applied in situations where the field name and its capitalization were being explicitly overridden in the gqlgen config. This was a problem because that filter changes the capitalization of field names that are already valid in Go in a slightly opinionated way, which was unwanted behavior in this case.

[carldunham]

Got it. Cool.

[YogeshLele]

@ianling Is there a way (in config or otherwise) to disable this?

[ianling]

@YogeshLele disable what exactly? If you want to specify a particular capitalization for a field in your schema, this PR made it so you can do so without gqlgen overriding it.

[MohitVachhani]

Will this work for the cases of enums ?