new /x/jsonx and /x/mathx util sub-packages

x/jsonx/simple_date.go

@@ -0,0 +1,113 @@
+package jsonx
+
+import (
+	"database/sql/driver"
+	"fmt"
+	"strconv"
+	"time"
+)
+
+// SimpleDateLayout represents the "year-month-day" Go time format.
+const SimpleDateLayout = "2006-01-02"
+
+// SimpleDate holds a json "year-month-day" time.
+type SimpleDate time.Time
+
+// ParseSimpleDate reads from "s" and returns the SimpleDate time.
+func ParseSimpleDate(s string) (SimpleDate, error) {
+	if s == "" || s == "null" {
+		return SimpleDate{}, nil
+	}
+
+	var (
+		tt  time.Time
+		err error
+	)
+
+	tt, err = time.Parse(SimpleDateLayout, s)
+	if err != nil {
+		return SimpleDate{}, err
+	}
+
+	return SimpleDate(tt.UTC()), nil
+}
+
+// UnmarshalJSON binds the json "data" to "t" with the `SimpleDateLayout`.
+func (t *SimpleDate) UnmarshalJSON(data []byte) error {
+	if isNull(data) {
+		return nil
+	}
+
+	data = trimQuotes(data)
+	dataStr := string(data)
+	if len(dataStr) == 0 {
+		return nil // as an excepption here, allow empty "" on simple dates, as the server would render it on a response: https://endomedical.slack.com/archives/D02BF660JA1/p1630486704048100.
+	}
+
+	tt, err := time.Parse(SimpleDateLayout, dataStr)
+	if err != nil {
+		return err
+	}
+
+	*t = SimpleDate(tt)
+	return nil
+}
+
+// MarshalJSON returns the json representation of the "t".
+func (t SimpleDate) MarshalJSON() ([]byte, error) {
+	if s := t.String(); s != "" {
+		s = strconv.Quote(s)
+		return []byte(s), nil
+	}
+
+	return emptyQuoteBytes, nil
+}
+
+// IsZero reports whether "t" is zero time.
+// It completes the pg.Zeroer interface.
+func (t SimpleDate) IsZero() bool {
+	return t.ToTime().IsZero()
+}
+
+// ToTime returns the standard time type.
+func (t SimpleDate) ToTime() time.Time {
+	return time.Time(t)
+}
+
+func (t SimpleDate) Value() (driver.Value, error) {
+	return t.String(), nil
+}
+
+// String returns the text representation of the date
+// formatted based on the `SimpleDateLayout`.
+// If date is zero it returns an empty string.
+func (t SimpleDate) String() string {
+	tt := t.ToTime()
+	if tt.IsZero() {
+		return ""
+	}
+
+	return tt.Format(SimpleDateLayout)
+}
+
+// Scan completes the pg and native sql driver.Scanner interface
+// reading functionality of a custom type.
+func (t *SimpleDate) Scan(src interface{}) error {
+	switch v := src.(type) {
+	case time.Time: // type was set to timestamp
+		if v.IsZero() {
+			return nil // don't set zero, ignore it.
+		}
+		*t = SimpleDate(v)
+	case string:
+		tt, err := ParseSimpleDate(v)
+		if err != nil {
+			return err
+		}
+		*t = tt
+	default:
+		return fmt.Errorf("SimpleDate: unknown type of: %T", v)
+	}
+
+	return nil
+}