github.com/99designs/gqlgen@v0.17.45/graphql/omittable.go (about)

     1  package graphql
     2  
     3  import "encoding/json"
     4  
     5  // Omittable is a wrapper around a value that also stores whether it is set
     6  // or not.
     7  type Omittable[T any] struct {
     8  	value T
     9  	set   bool
    10  }
    11  
    12  var (
    13  	_ json.Marshaler   = Omittable[struct{}]{}
    14  	_ json.Unmarshaler = (*Omittable[struct{}])(nil)
    15  )
    16  
    17  func OmittableOf[T any](value T) Omittable[T] {
    18  	return Omittable[T]{
    19  		value: value,
    20  		set:   true,
    21  	}
    22  }
    23  
    24  func (o Omittable[T]) Value() T {
    25  	if !o.set {
    26  		var zero T
    27  		return zero
    28  	}
    29  	return o.value
    30  }
    31  
    32  func (o Omittable[T]) ValueOK() (T, bool) {
    33  	if !o.set {
    34  		var zero T
    35  		return zero, false
    36  	}
    37  	return o.value, true
    38  }
    39  
    40  func (o Omittable[T]) IsSet() bool {
    41  	return o.set
    42  }
    43  
    44  func (o Omittable[T]) MarshalJSON() ([]byte, error) {
    45  	if !o.set {
    46  		return []byte("null"), nil
    47  	}
    48  	return json.Marshal(o.value)
    49  }
    50  
    51  func (o *Omittable[T]) UnmarshalJSON(bytes []byte) error {
    52  	err := json.Unmarshal(bytes, &o.value)
    53  	if err != nil {
    54  		return err
    55  	}
    56  	o.set = true
    57  	return nil
    58  }