Request Unions
Unions are represented as a struct with fields prefixed by “Of” for each of its variants, only one field can be non-zero. The non-zero field will be serialized.
Sub-properties of the union can be accessed via methods on the union struct. These methods return a mutable pointer to the underlying data, if present.
Request Union Structure
// Only one field can be non-zero, use param.IsOmitted() to check if a field is set
type AnimalUnionParam struct {
OfCat *Cat `json:",omitzero,inline`
OfDog *Dog `json:",omitzero,inline`
}
Request Union Example
animal := AnimalUnionParam{
OfCat: &Cat{
Name: "Whiskers",
Owner: PersonParam{
Address: AddressParam{Street: "3333 Coyote Hill Rd", Zip: 0},
},
},
}
// Mutating a field
if address := animal.GetOwner().GetAddress(); address != nil {
address.ZipCode = 94304
}
Only one field of the union can be non-zero. Use param.IsOmitted() to check if a field is set.
Response Unions
In responses, unions are represented by a flattened struct containing all possible fields from each of the object variants.
To convert it to a variant use the .AsFooVariant() method or the .AsAny() method if present.
If a response value union contains primitive values, primitive fields will be alongside the properties but prefixed with Of and feature the tag json:"...,inline".
Response Union Structure
type AnimalUnion struct {
// From variants [Dog], [Cat]
Owner Person `json:"owner"`
// From variant [Dog]
DogBreed string `json:"dog_breed"`
// From variant [Cat]
CatBreed string `json:"cat_breed"`
// ...
JSON struct {
Owner respjson.Field
// ...
} `json:"-"`
}
Response Union Example
// If animal variant
if animal.Owner.Address.ZipCode == "" {
panic("missing zip code")
}
// Switch on the variant
switch variant := animal.AsAny().(type) {
case Dog:
case Cat:
default:
panic("unexpected type")
}
