Documentation
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Index ¶
- type OptionalNullable
- func (n OptionalNullable[T]) Get() (*T, bool)
- func (n OptionalNullable[T]) GetOrZero() (T, bool)
- func (n OptionalNullable[T]) GetUntyped() (interface{}, bool)
- func (n OptionalNullable[T]) IsNull() bool
- func (n OptionalNullable[T]) IsSet() bool
- func (n OptionalNullable[T]) MarshalJSON() ([]byte, error)
- func (n *OptionalNullable[T]) Set(value *T)
- func (n *OptionalNullable[T]) UnmarshalJSON(data []byte) error
- func (n *OptionalNullable[T]) Unset()
- type OptionalNullableInterface
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type OptionalNullable ¶
OptionalNullable represents a field that can distinguish between three states: 1. Set to a value: field is present with a non-nil value 2. Set to nil: field is present but explicitly set to null in JSON 3. Unset: field is omitted from JSON entirely
This type is designed to work with JSON marshaling/unmarshaling and supports the `omitempty` struct tag to properly omit unset fields from JSON output.
Usage:
type User struct {
Name OptionalNullable[string] `json:"name,omitempty"`
Age OptionalNullable[int] `json:"age,omitempty"`
Tags OptionalNullable[[]string] `json:"tags,omitempty"`
}
// Set to value
name := "John"
user.Name = From(&name)
// Set to nil (will appear as "name": null in JSON)
user.Name = From[string](nil)
// Leave unset (will be omitted from JSON with omitempty)
user := User{}
WARNING: Do NOT use *OptionalNullable[T] as a field type. Always use OptionalNullable[T] directly. Using *OptionalNullable[T] will break the omitempty behavior and JSON marshaling.
The type is implemented as a map[bool]*T where: - nil map represents unset state - Map with true key represents set state (value may be nil)
func From ¶
func From[T any](value *T) OptionalNullable[T]
From creates a new OptionalNullable with the given value. Pass nil to create a OptionalNullable that is set to null. Pass a pointer to a value to create a OptionalNullable with that value.
Examples:
hello := "hello" From(&hello) // set to "hello" From[string](nil) // set to null
func (OptionalNullable[T]) Get ¶
func (n OptionalNullable[T]) Get() (*T, bool)
Get returns the internal pointer and whether the field was set.
Return values: - (ptr, true): field was set (ptr may be nil if set to null) - (nil, false): field was unset/omitted
This method provides direct access to the internal pointer representation.
func (OptionalNullable[T]) GetOrZero ¶
func (n OptionalNullable[T]) GetOrZero() (T, bool)
GetOrZero returns the value and whether it was set.
Return values: - (value, true): field was set to a non-nil value - (zero, true): field was explicitly set to nil - (zero, false): field was unset/omitted
Examples:
val, ok := nullable.GetOrZero()
if !ok {
// Field was unset/omitted
} else if nullable.IsNull() {
// Field was explicitly set to null
} else {
// Field has a value: val
}
func (OptionalNullable[T]) GetUntyped ¶
func (n OptionalNullable[T]) GetUntyped() (interface{}, bool)
GetUntyped returns the value as interface{} and whether it was set. This is useful for reflection-based code that needs to work with the value without knowing the specific type T.
Return values: - (value, true): field was set to a non-nil value - (nil, true): field was explicitly set to nil - (nil, false): field was unset/omitted
func (OptionalNullable[T]) IsNull ¶
func (n OptionalNullable[T]) IsNull() bool
IsNull returns true if the OptionalNullable is explicitly set to nil. Returns false if the OptionalNullable is unset or has a value.
Note: This differs from traditional null checks because unset fields return false, not true. Use IsSet() to check if a field was provided.
func (OptionalNullable[T]) IsSet ¶
func (n OptionalNullable[T]) IsSet() bool
IsSet returns true if the OptionalNullable has been explicitly set (to either a value or nil). Returns false if the OptionalNullable is unset (omitted from JSON).
This is the key method for distinguishing between: - Set to nil: IsSet() = true, IsNull() = true - Unset: IsSet() = false, IsNull() = false
func (OptionalNullable[T]) MarshalJSON ¶
func (n OptionalNullable[T]) MarshalJSON() ([]byte, error)
MarshalJSON implements json.Marshaler.
Behavior: - Unset fields: omitted from JSON when struct field has omitempty tag - Null fields: serialized as "null" - Value fields: serialized as the actual value
The omitempty behavior works because an empty map is considered a zero value by Go's JSON package.
func (*OptionalNullable[T]) Set ¶
func (n *OptionalNullable[T]) Set(value *T)
Set sets the OptionalNullable to the given value pointer. Pass nil to set the field to null. Pass a pointer to a value to set the field to that value.
Examples:
nullable.Set(ptrFrom("hello")) // set to "hello"
nullable.Set(nil) // set to null
func (*OptionalNullable[T]) UnmarshalJSON ¶
func (n *OptionalNullable[T]) UnmarshalJSON(data []byte) error
UnmarshalJSON implements json.Unmarshaler.
Behavior: - "null" in JSON: sets the field to null (IsSet=true, IsNull=true) - Any other value: sets the field to that value (IsSet=true, IsNull=false) - Missing from JSON: field remains unset (IsSet=false, IsNull=false)
func (*OptionalNullable[T]) Unset ¶
func (n *OptionalNullable[T]) Unset()
Unset removes the value, making the field unset/omitted. After calling Unset(), IsSet() will return false and the field will be omitted from JSON output when using omitempty.
type OptionalNullableInterface ¶
type OptionalNullableInterface interface {
GetUntyped() (interface{}, bool)
}
NullableInterface defines the interface that all OptionalNullable[T] types implement. This interface provides untyped access to optional nullable values for reflection-based code.
func AsOptionalNullable ¶
func AsOptionalNullable(v reflect.Value) (OptionalNullableInterface, bool)
AsOptionalNullable attempts to convert a reflect.Value to a OptionalNullableInterface. This is a helper function for reflection-based code that needs to check if a value implements the optional nullable interface pattern.
Returns: - (nullable, true): if the value implements OptionalNullableInterface - (nil, false): if the value does not implement OptionalNullableInterface
Example usage:
if nullable, ok := AsOptionalNullable(reflectValue); ok {
if value, isSet := nullable.GetUntyped(); isSet {
// Handle the nullable value
}
}
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