first commit

pkg/database/tool.go

@@ -0,0 +1,88 @@
+package database
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"encoding/json"
+	"fmt"
+	"gorm.io/gorm"
+	"reflect"
+)
+
+type NullTime sql.NullTime
+
+func (n *NullTime) Scan(value any) error {
+	return (*sql.NullTime)(n).Scan(value)
+}
+
+func (n NullTime) Value() (driver.Value, error) {
+	if !n.Valid {
+		return nil, nil
+	}
+	return n.Time, nil
+}
+
+func (n NullTime) MarshalJSON() ([]byte, error) {
+	if n.Valid {
+		return json.Marshal(n.Time)
+	}
+	return json.Marshal(nil)
+}
+
+func (n *NullTime) UnmarshalJSON(b []byte) error {
+	if string(b) == "null" {
+		n.Valid = false
+		return nil
+	}
+	err := json.Unmarshal(b, &n.Time)
+	if err == nil {
+		n.Valid = true
+	}
+	return err
+}
+
+/*-----------------------------------------------------------*/
+
+type PaginateList struct {
+	Page  int64 `json:"page"`
+	Size  int64 `json:"size"`
+	Total int64 `json:"total"`
+	List  any   `json:"list"`
+}
+
+func Paginate(db *gorm.DB, model any, page, size int64) (*PaginateList, error) {
+	ptr := reflect.ValueOf(model)
+	if ptr.Kind() != reflect.Ptr {
+		return nil, fmt.Errorf("model must be pointer")
+	}
+
+	var total int64
+	err := db.Model(model).Count(&total).Error
+	if err != nil {
+		return &PaginateList{
+			Page:  page,
+			Size:  size,
+			Total: total,
+			List:  make([]any, 0),
+		}, err
+	}
+
+	offset := size * (page - 1)
+	err = db.Limit(int(size)).Offset(int(offset)).Find(model).Error
+
+	if err != nil {
+		return &PaginateList{
+			Page:  page,
+			Size:  size,
+			Total: total,
+			List:  make([]any, 0),
+		}, err
+	}
+
+	return &PaginateList{
+		Page:  page,
+		Size:  size,
+		Total: total,
+		List:  model,
+	}, nil
+}