Question

我从https://github.com/dejavuzhou/felix的示例项目开始学习Golang。

我的第一个项目已经运行良好。但是我想要一些自定义输出。我的意思是我想在获取订单数据时获取关联数据有很多，但失败了。

从我的简单案例开始，我有2个表（订单和 detail_order ）。一个订单具有一个或多个detail_order。

我的handler_order.go

    package handlers

    import (
        "github.com/berthojoris/ginbro/models"
        "github.com/gin-gonic/gin"
    )

    func init() {
        groupApi.GET("order", orderAll)
        groupApi.GET("order/:id", orderOne)
        groupApi.POST("order", orderCreate)
        groupApi.PATCH("order", orderUpdate)
        groupApi.DELETE("order/:id", orderDelete)
    }

    //All
    func orderAll(c *gin.Context) {
        mdl := models.Order{}
        query := &models.PaginationQuery{}
        err := c.ShouldBindQuery(query)
        if handleError(c, err) {
            return
        }
        list, total, err := mdl.All(query)
        if handleError(c, err) {
            return
        }
        jsonPagination(c, list, total, query)
    }

    //One
    func orderOne(c *gin.Context) {
        var mdl models.Order
        id, err := parseParamID(c)
        if handleError(c, err) {
            return
        }
        mdl.Id = id
        data, err := mdl.One()
        if handleError(c, err) {
            return
        }
        jsonData(c, data)
    }

    //Create
    func orderCreate(c *gin.Context) {
        var mdl models.Order
        err := c.ShouldBind(&mdl)
        if handleError(c, err) {
            return
        }
        err = mdl.Create()
        if handleError(c, err) {
            return
        }
        jsonData(c, mdl)
    }

    //Update
    func orderUpdate(c *gin.Context) {
        var mdl models.Order
        err := c.ShouldBind(&mdl)
        if handleError(c, err) {
            return
        }
        err = mdl.Update()
        if handleError(c, err) {
            return
        }
        jsonSuccess(c)
    }

    //Delete
    func orderDelete(c *gin.Context) {
        var mdl models.Order
        id, err := parseParamID(c)
        if handleError(c, err) {
            return
        }
        mdl.Id = id
        err = mdl.Delete()
        if handleError(c, err) {
            return
        }
        jsonSuccess(c)
    }

我的model_order.go

package models

import (
    "errors"
    "time"
)

var _ = time.Thursday

//Order
type Order struct {
    Id    uint    `gorm:"column:id" form:"id" json:"id" comment:"" sql:"int(10),PRI"`
    Total float64 `gorm:"column:total" form:"total" json:"total" comment:"" sql:"double"`
    OrderDetail []OrderDetail `gorm:"foreignkey:OrderID" json:"detail_order"`
}

//TableName
func (m *Order) TableName() string {
    return "order"
}

//One
func (m *Order) One() (one *Order, err error) {
    one = &Order{}
    err = crudOne(m, one)
    return
}

//All
func (m *Order) All(q *PaginationQuery) (list *[]Order, total uint, err error) {
    list = &[]Order{}
    total, err = crudAll(m, q, list)
    return
}

//Update
func (m *Order) Update() (err error) {
    where := Order{Id: m.Id}
    m.Id = 0

    return crudUpdate(m, where)
}

//Create
func (m *Order) Create() (err error) {
    m.Id = 0

    return mysqlDB.Create(m).Error
}

//Delete
func (m *Order) Delete() (err error) {
    if m.Id == 0 {
        return errors.New("resource must not be zero value")
    }
    return crudDelete(m)
}

我的model_order_detail.go

package models

import (
    "errors"
    "time"
)

var _ = time.Thursday

//OrderDetail
type OrderDetail struct {
    Id        uint    `gorm:"column:id" form:"id" json:"id" comment:"" sql:"int(10),PRI"`
    OrderId   int     `gorm:"column:order_id" form:"order_id" json:"order_id" comment:"" sql:"int(10),MUL"`
    ItemId    int     `gorm:"column:item_id" form:"item_id" json:"item_id" comment:"" sql:"int(10)"`
    ItemName  string  `gorm:"column:item_name" form:"item_name" json:"item_name" comment:"" sql:"varchar(100)"`
    ItemPrice float64 `gorm:"column:item_price" form:"item_price" json:"item_price" comment:"" sql:"double"`
}

//TableName
func (m *OrderDetail) TableName() string {
    return "order_detail"
}

//One
func (m *OrderDetail) One() (one *OrderDetail, err error) {
    one = &OrderDetail{}
    err = crudOne(m, one)
    return
}

//All
func (m *OrderDetail) All(q *PaginationQuery) (list *[]OrderDetail, total uint, err error) {
    list = &[]OrderDetail{}
    total, err = crudAll(m, q, list)
    return
}

//Update
func (m *OrderDetail) Update() (err error) {
    where := OrderDetail{Id: m.Id}
    m.Id = 0

    return crudUpdate(m, where)
}

//Create
func (m *OrderDetail) Create() (err error) {
    m.Id = 0

    return mysqlDB.Create(m).Error
}

//Delete
func (m *OrderDetail) Delete() (err error) {
    if m.Id == 0 {
        return errors.New("resource must not be zero value")
    }
    return crudDelete(m)
}

还有我的db_helper.go

package models

import (
    "errors"
    "fmt"
    "github.com/jinzhu/gorm"
    "reflect"
    "strconv"
    "strings"
)

//PaginationQuery gin handler query binding struct
type PaginationQuery struct {
    Where  string `form:"where"`
    Fields string `form:"fields"`
    Order  string `form:"order"`
    Offset uint   `form:"offset"`
    Limit  uint   `form:"limit"`
}

//String to string
func (pq *PaginationQuery) String() string {
    return fmt.Sprintf("w=%v_f=%s_o=%s_of=%d_l=%d", pq.Where, pq.Fields, pq.Order, pq.Offset, pq.Limit)
}

func crudAll(m interface{}, q *PaginationQuery, list interface{}) (total uint, err error) {
    var tx *gorm.DB
    total, tx = getResourceCount(m, q)
    if q.Fields != "" {
        columns := strings.Split(q.Fields, ",")
        if len(columns) > 0 {
            tx = tx.Select(q.Fields)
        }
    }
    if q.Order != "" {
        tx = tx.Order(q.Order)
    }
    if q.Offset > 0 {
        tx = tx.Offset(q.Offset)
    }
    if q.Limit <= 0 {
        q.Limit = 15
    }
    err = tx.Limit(q.Limit).Find(list).Error
    return
}

func crudOne(m interface{}, one interface{}) (err error) {
    if mysqlDB.Where(m).First(one).RecordNotFound() {
        return errors.New("resource is not found")
    }
    return nil
}

func crudUpdate(m interface{}, where interface{}) (err error) {
    db := mysqlDB.Model(where).Updates(m)
    if err = db.Error; err != nil {
        return
    }
    if db.RowsAffected != 1 {
        return errors.New("id is invalid and resource is not found")
    }
    return nil
}

func crudDelete(m interface{}) (err error) {
    //WARNING When delete a record, you need to ensure it’s primary field has value, and GORM will use the primary key to delete the record, if primary field’s blank, GORM will delete all records for the model
    //primary key must be not zero value
    db := mysqlDB.Delete(m)
    if err = db.Error; err != nil {
        return
    }
    if db.RowsAffected != 1 {
        return errors.New("resource is not found to destroy")
    }
    return nil
}
func getResourceCount(m interface{}, q *PaginationQuery) (uint, *gorm.DB) {
    var tx = mysqlDB.Model(m)
    conditions := strings.Split(q.Where, ",")
    for _, val := range conditions {
        w := strings.SplitN(val, ":", 2)
        if len(w) == 2 {
            bindKey, bindValue := w[0], w[1]
            if intV, err := strconv.ParseInt(bindValue, 10, 64); err == nil {
                // bind value is int
                field := fmt.Sprintf("`%s` > ?", bindKey)
                tx = tx.Where(field, intV)
            } else if fV, err := strconv.ParseFloat(bindValue, 64); err == nil {
                // bind value is float
                field := fmt.Sprintf("`%s` > ?", bindKey)
                tx = tx.Where(field, fV)
            } else if bindValue != "" {
                // bind value is string
                field := fmt.Sprintf("`%s` LIKE ?", bindKey)
                sV := fmt.Sprintf("%%%s%%", bindValue)
                tx = tx.Where(field, sV)
            }
        }
    }
    modelName := getType(m)
    rKey := redisPrefix + modelName + q.String() + "_count"
    v, err := mem.GetUint(rKey)
    if err != nil {
        var count uint
        tx.Count(&count)
        mem.Set(rKey, count)
        return count, tx
    }
    return v, tx
}

func getType(v interface{}) string {
    t := reflect.TypeOf(v)
    if t.Kind() == reflect.Ptr {
        return "*" + t.Elem().Name()
    }
    return t.Name()
}

在我的订单模型中，添加

OrderDetail []OrderDetail `gorm:"foreignkey:OrderID" json:"detail_order"`

关于我的关系数据。结果是

即使我有关系数据

我的问题是，如何在OrderDetail struct内添加/附加Order struct以便表关系数据出来。

谢谢

Answer 1

您需要在查询中添加Preload调用，或者在获得对象后添加Related调用。有关用法，请参见the Preload docs here或the Related docs。如果您使用Preload（为简便起见，建议您使用此功能），则可能不得不放弃crudOne函数或使其适应您的需求。

如何添加关系数据

1 个答案: