feat(helper): 数据库分页

helper.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"math"
 
 	"github.com/doug-martin/goqu/v9"
 	"github.com/jmoiron/sqlx"
@@ -115,3 +116,63 @@ func Transaction(db *sqlx.DB, fn func(tx *sqlx.Tx) error) (err error) {
 
 	return fn(tx)
 }
+
+// Pagination 数据库分页计算
+type Pagination struct {
+	First    int `json:"first"`
+	Last     int `json:"last"`
+	Previous int `json:"previous"`
+	Current  int `json:"current"`
+	Next     int `json:"next"`
+	Size     int `json:"size"`
+	Items    int `json:"items"`
+}
+
+// NewPagination 计算分页页码
+func NewPagination(current, size, items int) Pagination {
+	if current <= 0 {
+		current = 1
+	}
+
+	p := Pagination{
+		First:   1,
+		Last:    1,
+		Current: current,
+	}
+
+	if size > 0 {
+		p.Size = size
+	}
+	if items > 0 {
+		p.Items = items
+	}
+
+	if items > 0 && size > 0 {
+		p.Last = int(math.Ceil(float64(p.Items) / float64(p.Size)))
+	}
+
+	if p.Current < p.First {
+		p.Current = p.First
+	} else if p.Current > p.Last {
+		p.Current = p.Last
+	}
+
+	if p.Current > p.First {
+		p.Previous = p.Current - 1
+	}
+	if p.Current < p.Last {
+		p.Next = p.Current + 1
+	}
+
+	return p
+}
+
+// Limit 数据库查询LIMIT值
+func (p Pagination) Limit() int {
+	return p.Size
+}
+
+// Offset 数据库查询OFFSET值
+func (p Pagination) Offset() int {
+	return (p.Current - 1) * p.Size
+}

helper_test.go

@@ -0,0 +1,67 @@
+package entity
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestPagination(t *testing.T) {
+	cases := []struct {
+		Actual   Pagination
+		Excepted Pagination
+	}{
+		{
+			Actual: Pagination{
+				First:   1,
+				Last:    1,
+				Current: 1,
+				Size:    10,
+				Items:   0,
+			},
+			Excepted: NewPagination(1, 10, 0),
+		},
+		{
+			Actual: Pagination{
+				First:   1,
+				Last:    1,
+				Current: 1,
+				Size:    10,
+				Items:   9,
+			},
+			Excepted: NewPagination(1, 10, 9),
+		},
+		{
+			Actual: Pagination{
+				First:   1,
+				Last:    2,
+				Current: 1,
+				Next:    2,
+				Size:    10,
+				Items:   11,
+			},
+			Excepted: NewPagination(1, 10, 11),
+		},
+		{
+			Actual: Pagination{
+				First:    1,
+				Last:     3,
+				Previous: 1,
+				Current:  2,
+				Next:     3,
+				Size:     10,
+				Items:    21,
+			},
+			Excepted: NewPagination(2, 10, 21),
+		},
+		{
+			Actual:   NewPagination(3, 10, 21),
+			Excepted: NewPagination(4, 10, 21),
+		},
+	}
+
+	for _, c := range cases {
+		if !reflect.DeepEqual(c.Actual, c.Excepted) {
+			t.Fatalf("Pagination, Actual=%+v, Excepted=%+v\n", c.Actual, c.Excepted)
+		}
+	}
+}