enahs · January 4, 2022 23:52 · Jan 4, 2022 · Jan 4, 2022 · Jan 4, 2022
diff --git a/nullstring.go b/nullstring.go
@@ -7,7 +7,7 @@ import (
 )
 
 // make a json'able null string
-// - respects omitempty
+// - doesn't respect omitempty
 // - null ~> null, valid = false
 // - "" ~> "" , valid = true
 // - "val" = "val", valid = true

diff --git a/nullstring.go b/nullstring.go
@@ -0,0 +1,113 @@
+package main
+
+import (
+	"database/sql"
+	"encoding/json"
+	"fmt"
+)
+
+// make a json'able null string
+// - respects omitempty
+// - null ~> null, valid = false
+// - "" ~> "" , valid = true
+// - "val" = "val", valid = true
+
+const Null = "null"
+
+type NullString struct {
+	sql.NullString
+}
+
+func NewNullString(s *string) NullString {
+	var str string
+	if s == nil {
+		str = Null
+	} else {
+		str = *s
+	}
+	return NullString{
+		sql.NullString{
+			String: str,
+			Valid:  s != nil,
+		},
+	}
+
+}
+
+func (ns NullString) MarshalJSON() ([]byte, error) {
+
+	var value string
+	if ns.Valid == true {
+		value = fmt.Sprintf("\"%s\"", ns.String)
+	} else {
+		value = Null
+	}
+
+	return []byte(value), nil
+}
+
+func (ns *NullString) UnmarshalJSON(b []byte) error {
+	var s *string
+	if err := json.Unmarshal(b, &s); err != nil {
+		return err
+	}
+	if s == nil {
+		ns.String = Null
+		ns.Valid = false
+	} else {
+		ns.String = *s
+		ns.Valid = true
+	}
+	return nil
+}
+
+type T struct {
+	Reg           string     `json:"reg"`
+	Nullish       NullString `json:"nullish"`
+	OmitReg       string     `json:"omitreg,omitempty"`
+	OmitNullish   NullString `json:"omitnull,omitempty"`
+	expectedValue string     `json:"-"`
+}
+
+func main() {
+	emptyStr := ""
+	fullStr := "yadda yadda"
+	var PtrToStr *string
+	testers := []T{
+		// empty string
+		T{
+			Reg:           emptyStr,
+			Nullish:       NewNullString(&emptyStr),
+			OmitReg:       emptyStr,
+			OmitNullish:   NewNullString(&emptyStr),
+			expectedValue: `{"reg":"","nullish":"","omitnull":""}`,
+		},
+		// regular string
+		T{
+			Reg:           fullStr,
+			Nullish:       NewNullString(&fullStr),
+			OmitReg:       fullStr,
+			OmitNullish:   NewNullString(&fullStr),
+			expectedValue: `{"reg":"yadda yadda","nullish":"yadda yadda","omitreg":"yadda yadda","omitnull":"yadda yadda"}`,
+		},
+		// pointer to string that is null
+		T{
+			Reg:           Null,
+			Nullish:       NewNullString(PtrToStr),
+			OmitReg:       Null,
+			OmitNullish:   NewNullString(PtrToStr),
+			expectedValue: `{"reg":"null","nullish":null,"omitreg":"null","omitnull":null}`,
+		},
+	}
+	for _, t := range testers {
+		b, _ := json.Marshal(t)
+		fmt.Println(string(b))
+		newT := T{}
+		err := json.Unmarshal([]byte(t.expectedValue), &newT)
+		if err != nil {
+			fmt.Println("error", err)
+		}
+		fmt.Printf("thing:\n%#v\n", newT)
+	}
+
+}
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