// 创建一个查询
tx := db.Where("name = ", "jinzhu")
// 添加更多条件
if someCondition {
 tx = tx.Where("age = ", 20)
} else {
 tx = tx.Where("age = ", 30)
}
if yetAnotherCondition {
 tx = tx.Where("active = ", 1)
}

func (xy *Topic) GetTopicListByTimeGenderAddress(createTime, gender int, date, cityName string, adsID int64) (TopicList []Topic) {
 //先创建一个查询
 tx := Db.Model(&xy).Where("ads_id = ", adsID)
 //分类
 if adsID > 0 {
 tx = tx.Where("ads_id = ", adsID)
 }
 //按照创建时间筛选
 if createTime > 0 {
 tx = tx.Order("create_time desc")
 } else {
 //按照活动时间筛选
 tx = tx.Order("date_timestamp asc")
 }
 if gender > 0 {
 tx = tx.Where("gender = ", gender)
 }
 if cityName != "" {
 tx = tx.Where("city_name = ", cityName)
 }
 tx = tx.Preload("TopicImagesList")
 tx.Find(&TopicList).RecordNotFound()
 return TopicList
}

type User struct {
  gorm.Model
  Birthday   time.Time
  Age     int
  Name     string `gorm:"size:255"`
  Num     int   `gorm:"AUTO_INCREMENT"`
  Sex     string `gorm:"size:"`
}

var db *gorm.DB  // 已经进行了db的初始化操作,db为全局变量
func getUsers(c *gin.Context) {
  users := make([]User, 0)
  Db := db   
  if age, isExist := c.GetQuery("age"); isExist == true {
    ageInt, _ := strconv.Atoi(age)
    Db = Db.Where("age = ", ageInt)
  }
  if num, isExist := c.GetQuery("num"); isExist == true {
    numInt, _ := strconv.Atoi(num)
    Db = Db.Where("num = ", numInt)
  }
  if name, isExist := c.GetQuery("name"); isExist == true {
    Db = Db.Where("name = ", name)
  }
  if err := Db.Find(&users).Error; err != nil {
    fmt.Println(err.Error())
  }
  c.JSON(http.StatusOK, gin.H{
    "data": users,
  })
}

[2018-09-03 18:47:26] [1.03ms] SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL AND ((age = '26') AND (name = 'zhangchi')) 
[13 rows affected or returned ] 
[GIN] 2018/09/03 - 18:47:26 | 200 |  1.263889ms |    127.0.0.1 | GET   /user/"htmlcode">

func getUsers(c *gin.Context) {
  users := make([]User, 0)
  Db := db
  page, _ := strconv.Atoi(c.Query("page"))
  pageSize, _ := strconv.Atoi(c.Query("page_size"))
  if age, isExist := c.GetQuery("age"); isExist == true {
    ageInt, _ := strconv.Atoi(age)
    Db = Db.Where("age = ", ageInt)
  }
  if num, isExist := c.GetQuery("num"); isExist == true {
    numInt, _ := strconv.Atoi(num)
    Db = Db.Where("num = ", numInt)
  }
  if name, isExist := c.GetQuery("name"); isExist == true {
    Db = Db.Where("name = ", name)
  }
  if page > 0 && pageSize > 0 {
    Db = Db.Limit(pageSize).Offset((page - 1) * pageSize)
  }
  if err := Db.Find(&users).Error; err != nil {
    fmt.Println(err.Error())
  }
  c.JSON(http.StatusOK, gin.H{
    "data": users,
  })
}



最核心的代码如下:


if page > 0 && pageSize > 0 {
  Db = Db.Limit(pageSize).Offset((page - 1) * pageSize)
}



limit定位每页大小, Offset定位偏移的查询位置.并且先进行条件筛选,最后做分页操作.
小结
分页和不定条件查询主要是配合前端的table进行操作,用户可以根据所需的条件进行筛选.为了提高访问效率,可以指定table的每页大小.
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。如有错误或未考虑完全的地方，望不吝赐教。