增加实现和readme说明

Author: xfali

.gitignore

@@ -13,3 +13,6 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+
+*.zip
+/.idea/

README.md

@@ -0,0 +1,42 @@
+# pagehelper
+
+## 介绍
+
+pagehelper是与[gobatis](https://github.com/xfali/gobatis)配套的分页工具
+
+## 待完成项
+
+select查询返回的result还未能携带page、pageSize、total信息，需要自己组装。
+
+（此功能需gobatis支持，暂未实现）
+
+## 使用
+
+### 1、使用pagehelper的Factory生成SessionManager
+
+```cassandraql
+    fac := factory.DefaultFactory{
+        Host:     "localhost",
+        Port:     3306,
+        DBName:   "test",
+        Username: "root",
+        Password: "123",
+        Charset:  "utf8",
+
+        MaxConn:     1000,
+        MaxIdleConn: 500,
+
+        Log: logging.DefaultLogf,
+    }
+    sessMgr := gobatis.NewSessionManager(pagehelper.New(&fac))
+```
+
+### 2、配置分页参数
+```cassandraql
+    session := sessMgr.NewSession()
+    ctx, _ := context.WithTimeout(context.Background(), 2*time.Second)
+    ctx = pagehelper.StartPage(1, 2, ctx)
+
+    var ret []TestTable
+    session.SetContext(ctx).Select("SELECT * FROM TBL_TEST").Param().Result(&ret)
+```

go.mod

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+module github/xfali/pagehelper
+
+go 1.12
+
+require github.com/xfali/gobatis v0.0.4

go.sum

@@ -0,0 +1,3 @@
+github.com/go-sql-driver/mysql v1.4.1/go.mod h1:zAC/RDZ24gD3HViQzih4MyKcchzm+sOG5ZlKdlhCg5w=
+github.com/xfali/gobatis v0.0.4 h1:rBR8m18xMQAL58jDIr+i9zj8RYC+Mfa9rOw4ZB3shf0=
+github.com/xfali/gobatis v0.0.4/go.mod h1:hXP3PcXMSYpYFHQejG04qQjSQJtrt8jWpslftkUMBrg=

pagehelper.go

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+/**
+ * Copyright (C) 2019, Xiongfa Li.
+ * All right reserved.
+ * @author xiongfa.li
+ * @version V1.0
+ * Description:
+ */
+
+package pagehelper
+
+import (
+    "context"
+    "fmt"
+    "github.com/xfali/gobatis/executor"
+    "github.com/xfali/gobatis/factory"
+    "github.com/xfali/gobatis/reflection"
+    "github.com/xfali/gobatis/transaction"
+    "strings"
+)
+
+const (
+    pageHelperValue = "_page_helper_value"
+)
+
+type PageParam struct {
+    Page     int
+    PageSize int
+}
+
+func New(f *factory.DefaultFactory) *PageHelperFactory {
+    return &PageHelperFactory{*f}
+}
+
+type PageHelperFactory struct {
+    factory.DefaultFactory
+}
+
+type PageHelperExecutor struct {
+    executor.SimpleExecutor
+}
+
+func StartPage(page, pageSize int, ctx context.Context) context.Context {
+    return context.WithValue(ctx, pageHelperValue, &PageParam{Page: page, PageSize: pageSize})
+}
+
+func (exec *PageHelperExecutor) Query(ctx context.Context, result reflection.Object, sql string, params ...interface{}) error {
+    p := ctx.Value(pageHelperValue)
+    if p != nil {
+        if param, ok := p.(*PageParam); ok {
+            sql = modifySql(sql, param)
+        }
+    }
+
+    return exec.SimpleExecutor.Query(ctx, result, sql, params...)
+}
+
+func (f *PageHelperFactory) CreateExecutor(transaction transaction.Transaction) executor.Executor {
+    return &PageHelperExecutor{*executor.NewSimpleExecutor(transaction)}
+}
+
+func modifySql(sql string, p *PageParam) string {
+    b := strings.Builder{}
+    b.WriteString(sql)
+    b.WriteString(fmt.Sprintf(" OFFSET %d LIMIT %d ", p.Page*p.PageSize, p.PageSize))
+    return b.String()
+}

pagehelper_test.go

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+/**
+ * Copyright (C) 2019, Xiongfa Li.
+ * All right reserved.
+ * @author xiongfa.li
+ * @version V1.0
+ * Description:
+ */
+
+package pagehelper
+
+import (
+    "context"
+    "github.com/xfali/gobatis"
+    "github.com/xfali/gobatis/factory"
+    "github.com/xfali/gobatis/logging"
+    "testing"
+    "time"
+)
+
+type TestTable struct {
+    TestTable gobatis.ModelName "test_table"
+    Id        int64             `xfield:"id"`
+    Username  string            `xfield:"username"`
+    Password  string            `xfield:"password"`
+}
+
+func TestPageHelper(t *testing.T) {
+    ctx, _ := context.WithTimeout(context.Background(), 2*time.Second)
+    ctx = StartPage(1, 2, ctx)
+
+    p := ctx.Value(pageHelperValue)
+    printV(t, p)
+
+    select {
+    case <-ctx.Done():
+        break
+    }
+    printV(t, p)
+}
+
+func TestPageHelper2(t *testing.T) {
+    fac := factory.DefaultFactory{
+        Host:     "localhost",
+        Port:     3306,
+        DBName:   "test",
+        Username: "root",
+        Password: "123",
+        Charset:  "utf8",
+
+        MaxConn:     1000,
+        MaxIdleConn: 500,
+
+        Log: logging.DefaultLogf,
+    }
+    sessMgr := gobatis.NewSessionManager(New(&fac))
+    session := sessMgr.NewSession()
+    ctx, _ := context.WithTimeout(context.Background(), 2*time.Second)
+    ctx = StartPage(1, 2, ctx)
+
+    session.SetContext(ctx)
+
+    var ret []TestTable
+    session.Select("SELECT * FROM TBL_TEST").Param().Result(&ret)
+}
+
+func TestModify(t *testing.T) {
+    sql := modifySql("select * from x", &PageParam{1, 2})
+    t.Log(sql)
+}
+
+func printV(t *testing.T, p interface{}) {
+    if p, ok := p.(*PageParam); ok {
+        t.Logf("param: %d %d", p.Page, p.PageSize)
+    } else {
+        t.Fail()
+    }
+}
+
+func TestContext(t *testing.T) {
+    ctx, _ := context.WithTimeout(context.Background(), 2*time.Second)
+    ctx = context.WithValue(ctx, "1", "a")
+
+    t.Log(ctx.Value("1"))
+    select {
+    case <-ctx.Done():
+        break
+    }
+    t.Log(ctx.Value("1"))
+}
+
+type A struct{ I int }
+type B struct{ A }
+
+func TestStruct(t *testing.T) {
+    a := &A{10}
+    b := B{*a}
+    t.Logf("b:%d\n", b.I)
+    if b.I != 10 {
+        t.Fail()
+    }
+}