sq

types/nullable_new_test.go

@@ -0,0 +1,109 @@
+package types_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+/* ...... */
+// Adapted from https://www.calhoun.io/how-to-determine-if-a-json-key-has-been-set-to-null-or-not-provided/
+type Nullable[T any] struct {
+	// Value contains the underlying value of the field. If `Set` is true, and `Null` is false, **??**
+	Value *T
+	// Set will be true if the field was sent
+	Set bool
+	// Valid will be true if the value is a valid type - either a value of T or as an explicit `null`
+	Valid bool
+}
+
+func (t *Nullable[T]) UnmarshalJSON(data []byte) error {
+	// If this method is called, there was a value explicitly sent, which was either <nil> or a value of `T`
+	t.Set = true
+
+	// we received an explicit value of null
+	if string(data) == "null" {
+		// which is deemed valid, because we allow either <nil> or a value of `T`
+		t.Valid = true
+		t.Value = nil
+		return nil
+	}
+
+	// we received a value of `T`
+	var temp T
+	if err := json.Unmarshal(data, &temp); err != nil {
+		return fmt.Errorf("couldn't unmarshal JSON: %w", err)
+	}
+	t.Value = &temp
+	t.Valid = true
+	return nil
+}
+
+/* </adapted from https://www.calhoun.io/how-to-determine-if-a-json-key-has-been-set-to-null-or-not-provided/> */
+/* ...... */
+
+func (t Nullable[T]) IsSet() bool {
+	return t.Set
+}
+
+func (t Nullable[T]) IsValid() bool {
+	return t.Valid
+}
+
+func TestNullable2(t *testing.T) {
+	obj := struct {
+		ID Nullable[int] `json:"id"`
+	}{}
+
+	// when unset
+	obj.ID = Nullable[int]{}
+	assert.False(t, obj.ID.IsSet())
+	assert.False(t, obj.ID.IsValid())
+	assert.Nil(t, obj.ID.Value)
+
+	// when empty body
+	obj.ID = Nullable[int]{}
+	err := json.Unmarshal([]byte("{}"), &obj)
+	require.NoError(t, err)
+	fmt.Printf("empty\t%v: %v %v\n", obj.ID, obj.ID.IsSet(), obj.ID.IsValid())
+
+	assert.False(t, obj.ID.IsSet())
+	assert.False(t, obj.ID.IsValid())
+	assert.Nil(t, obj.ID.Value)
+
+	// when explicit null body
+	obj.ID = Nullable[int]{}
+	err = json.Unmarshal([]byte(`{"id": null}`), &obj)
+	require.NoError(t, err)
+	fmt.Printf("null\t%v: %v %v\n", obj.ID, obj.ID.IsSet(), obj.ID.IsValid())
+
+	assert.True(t, obj.ID.IsSet())
+	assert.True(t, obj.ID.IsValid())
+	assert.Nil(t, obj.ID.Value)
+
+	// when explicit zero value
+	obj.ID = Nullable[int]{}
+	err = json.Unmarshal([]byte(`{"id": 0}`), &obj)
+	require.NoError(t, err)
+	fmt.Printf("zero\t%v: %v %v\n", obj.ID, obj.ID.IsSet(), obj.ID.IsValid())
+	assert.True(t, obj.ID.IsSet())
+	assert.True(t, obj.ID.IsValid())
+	if assert.NotNil(t, obj.ID.Value) {
+		assert.Equal(t, 0, *obj.ID.Value)
+	}
+
+	// when explicit value
+	obj.ID = Nullable[int]{}
+	err = json.Unmarshal([]byte(`{"id": 1230}`), &obj)
+	require.NoError(t, err)
+	fmt.Printf("val\t%v: %v %v\n", obj.ID, obj.ID.IsSet(), obj.ID.IsValid())
+	assert.True(t, obj.ID.IsSet())
+	assert.True(t, obj.ID.IsValid())
+	if assert.NotNil(t, obj.ID.Value) {
+		assert.Equal(t, 1230, *obj.ID.Value)
+	}
+	assert.True(t, obj.ID.Valid)
+}