动态生成SQL语句， 通用查询接口

很多时候，由于业务变化，使得同一数据表在不同业务模块中查询条件不同；例如：用户表在其模块管理页面中，需要根据用户名，真实姓名查询；而在课程报名时，则需要根据用户所在专业进修过滤。这种情况在后端查询接口中全部兼容，另外实现动态SQL语句生成，满足条件由前端进行根据需要进行配置。
1、查询条件配置如下：

{"groupOp":"AND", "rules":[{"field":"name","op":"cn","data":"1"},{"field":"major","op":"eq","data":"110"}], "groups":null}
// 表示 name like '%1%' and major = 110

同样也可以表示更复杂的条件，如下

		{
		    "groupOp":"AND",
		    "rules":[{"field":"major","op":"eq","data":"110"}],
		    "groups":[
				{
				    "groupOp":"OR",
				    "rules":[{"field":"name","op":"cn","data":"ad"},{"field":"login_id","op":"cn","data":"ad"}],
				    "groups":[]
				}
			]
		}
		// 表示 ( `major` = ? ) AND (( `name` LIKE ?  OR  `login_id` LIKE ? ))

2、后端解析
注意：后端用go语言，使用gin+xorm
2.1、实体对象：

type QueryResult struct {
	Page   int         `json:"page"`   //页码，从1开始
	TotalRows   int         `json:"totalRows"`   // 页行数
	TotalPages  int         `json:"totalPages"`  // 总页数
	Result interface{} `json:"result"` // 结果
}

type QueryParam struct {
	Rows       int           `form:"rows"json:"rows"`     // 页行数
	Page       int           `form:"page"json:"page"`     // 页码，从1开始
	Sort       string        `form:"sort"json:"sort"`     // 排序，类似与name,age desc
	Filter     sqlgen.Filter `form:"filter"json:"filter"` // 过滤条件
	Table      string        `form:"-"json:"-"`           // 表名
	Selects    []string      `form:"-"json:"-"`           // select 字段列表
	JoinParams []JoinParam   `form:"-"json:"-"`           // 连接表列表
}

2.2 解析

/**
 * @brief: 生成where条件语句
 * @ @param1 tableName: 表名
 * @return1: where条件语句
 * @return2: 条件值列表
 * @return3: u错误信息
 */
func (f *Filter) GenWhereStmt(tableName string) (string, []interface{}, error) {

	whereStatement := ""
	groupWhereStatement := ""
	datas := make([]interface{}, 0)

	isAnd := true
	if strings.ToLower(strings.TrimSpace(f.GroupOp)) == "or" {
		isAnd = false
	}

	if len(f.Rules) > 0 {
		whereStr, ruleDatas := f.GenRuleWhereStmt(tableName, f.Rules[0])
		if whereStr != "" {
			whereStatement = whereStr
			for _, ruleData := range ruleDatas {
				datas = append(datas, ruleData)
			}
		} else {
			return whereStatement, datas, errors.New(fmt.Sprintf("the 0 rule is invalid"))
		}
		for i := 1; i < len(f.Rules); i++ {
			whereStr, ruleDatas = f.GenRuleWhereStmt(tableName, f.Rules[i])
			if whereStr != "" {
				if isAnd {
					whereStatement += " AND " + whereStr
				} else {
					whereStatement += " OR " + whereStr
				}
				for _, ruleData := range ruleDatas {
					datas = append(datas, ruleData)
				}
			} else {
				return whereStatement, datas, errors.New(fmt.Sprintf("the %d rule is invalid", i))
			}
		}
	}

	if len(f.Groups) > 0 {

		whereStr, groupDatas, err := f.Groups[0].GenWhereStmt(tableName)
		if err != nil {
			return whereStatement, datas, err
		}
		if whereStr != "" {
			groupWhereStatement = whereStr
			for _, groupData := range groupDatas {
				datas = append(datas, groupData)
			}
		} else {
			return whereStatement, datas, errors.New("the 0 group is invalid")
		}
		for i := 1; i < len(f.Groups); i++ {
			whereStr, groupDatas, err := f.Groups[i].GenWhereStmt(tableName)
			if err != nil {
				return whereStatement, datas, err
			}
			if whereStr != "" {
				if isAnd {
					groupWhereStatement += " AND " + whereStr
				} else {
					groupWhereStatement += " OR " + whereStr
				}
				for _, groupData := range groupDatas {
					datas = append(datas, groupData)
				}
			} else {
				return whereStatement, datas, errors.New(fmt.Sprintf("the %d group is invalid", i))
			}
		}
		if groupWhereStatement != "" {
			groupWhereStatement = "(" + groupWhereStatement + ")"
		}
	}
	if whereStatement == "" {
		whereStatement = groupWhereStatement
	} else {
		whereStatement = "(" + whereStatement + ")"
		if groupWhereStatement != "" {
			if isAnd {
				whereStatement += " AND " + groupWhereStatement
			} else {
				whereStatement += " OR " + groupWhereStatement
			}
		}
	}

	return whereStatement, datas, nil
}

具体代码见https://github.com/hrf304/ukid.git
后续根据需求配合角色权限表可以实现数据权限控制