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Make arrays use concrete types, not aliases.#1246

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jamietanna merged 1 commit intooapi-codegen:masterfrom
jkj:unaliased-types-for-arrays
Jan 25, 2024
Merged

Make arrays use concrete types, not aliases.#1246
jamietanna merged 1 commit intooapi-codegen:masterfrom
jkj:unaliased-types-for-arrays

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@jkj
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@jkj jkj commented Sep 8, 2023

Currently when you create an array type using something like:

components:
  schemas:
    my_item:
      type: object
      properties:
        name:
          type: string
        age:
          type: integer
    example:
      type: array
      items:
        $ref: '#/components/schemas/my_item'

the generator produces a type alias for the array:

// Example defines model for example.
type Example = []MyItem

This causes problems, particularly for defining methods. This patch ensures that when arrays are generated, they use a concrete type and not a type alias. For example:

// Example defines model for example.
type Example []MyItem

The following example indicates why aliases are bad:

type item struct {
        name string
        age int
}

type Alias = []item
type Concrete []item

// func (*Alias) wont_compile() {
//     invalid receiver type *[]item
// }

func (*Concrete) will_compile() {
}

This is especially problematic if you need to create methods for things like a JSON Scan() method or an SQL Value() method for the type.

@jkj jkj mentioned this pull request Sep 8, 2023
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@jamietanna jamietanna added this to the v1.16.0 milestone Sep 17, 2023
@jamietanna jamietanna modified the milestones: v1.16.0, v2.1.0 Oct 23, 2023
@jamietanna
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jamietanna commented Dec 13, 2023

Thanks for raising this @jkj - this will be a breaking change, so we'd need to mark this behind an output-options feature flag, so folks can opt-in to this behaviour. Would you be OK to make the change?

@zsolt-p
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zsolt-p commented Jan 24, 2024

need to create methods for things like a JSON Scan() method or an SQL Value() method for the type.

I have this same exact use case, too.

my workaround is:

  • add the schema to my spec anyway (I do this so I can still $ref the type, etc)
  • -exclude-schemas=mySchema when I generate
  • implement the concrete type by hand outside the genned code within the same package, where I can implement its methods, etc

@jamietanna jamietanna added enhancement New feature or request and removed awaiting reply labels Jan 25, 2024
@jkj @jamietanna
Allow disabling type aliases for arrays
081a800 
As noted in #1247, in some cases it can be useful to have arrays defined
as a concrete type, not a type alias, so you are able to extend them
with methods.

This produces a new opt-in output-option,
`disable-type-aliases-for-type`, which can be used to control this
behaviour

Right now, we only want to add support for `array`s, but the
configuration is extensible in the future.

This also introduces a test case to demonstrate the capabilities.

We need to introduce a `sliceContains` method to simplify this lookup,
as we don't yet have `slices.Contains` due to the Go versions we're
targeting.
@jamietanna jamietanna merged commit 5cdb559 into oapi-codegen:master Jan 25, 2024
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@jkj @jamietanna @zsolt-p