XPO 学习笔记(五)
1.绑定一般的DropDownList
M_ReferringAgentAndGP是一个对应数据库表的实体类,
M0201是要显示的文本,M0200要显示的文本对应的值域
Dim Agent As XPCollection = New XPCollection(GetType(M_ReferringAgentAndGP))
ddlF1609.DataSource = Agent
ddlF1609.DataTextField = "M0201"
ddlF1609.DataValueField = "M0200"
ddlF1609.DataBind()
2.绑定有组合字段的DropDownList
M_StaffDetails类中有M0000,M0002,M0003字段域,分别对应主鍵,FirstName,LastName
Dim sName As XPCollection = New XPCollection(GetType(M_StaffDetails))
ddlF1617.DataSource = sName
ddlF1617.DataTextField = "FullName"
ddlF1617.DataValueField = "M0000"
ddlF1617.DataBind()
在M_StaffDetails类中加入如下属性:
<Persistent()> _
Public ReadOnly Property FullName() As String
Get
Return String.Format("{0} {1}", M0002, M0003)
End Get
End Property
在生成数据库时会把FullName当作一个字段创建出来
3.通过主鍵获得唯一一条记录
F_DomesticViolence是对应数据库中的一个表的类,ID是这个表的主鍵
Dim bizObject As New F_DomesticViolence
Dim newSession As New DevExpress.Xpo.Session
newSession.ConnectionString = DevExpress.Xpo.Session.DefaultSession.ConnectionString
bizObject = newSession.GetObjectByKey(GetType(F_DomesticViolence), CStr(ID))
4.新增和保存一条记录
加重显示的地方是关键,开始没这样写,导致每次操作都是新增数据,后来想到由于是持久性对象,所以
只要不释放,它一直都存在,如果每次都 Dim bizObject As New ... ,那么每点保存按钮时,重新建立一个对象
所以导致每次都是新增数据,要想保存必须找到以前的持久性对象,所以用了如下方法!
Dim bizObject As New F_DomesticViolence
If Request.QueryString("mode") = "edit" Then
bizObject = New XPCollection(GetType(F_DomesticViolence), New BinaryOperator("F1600", editID, BinaryOperatorType.Equal)).Object(0)
End If
With bizObject
.F1601 = chkF1601.Checked
.F1602 = chkF1602.Checked
.F1603 = chkF1603.Checked
.F1604 = chkF1604.Checked
.F1605 = ddlF1605.SelectedValue
.F1606 = chkF1606.Checked
.F1607 = chkF1607.Checked
.F1608 = chkF1608.Checked
.F1609 = ddlF1609.SelectedValue
.F1610 = txtF1610.Text
.F1611 = txtF1611.Text
.F1613 = chkF1613.Checked
.F1614 = chkF1614.Checked
.F1615 = chkF1615.Checked
.F1616 = txtF1616.Text
.F1617 = ddlF1617.SelectedValue
.F1618 = saveDateNull(txtF1618)
.F1619 = txtF1619.Text
'If Request.QueryString("mode") = "edit" Then
'.F1600 = 9
'End If
.Save()
End With
5.多条件查询,返回对象集合!
加重显示的语句可以增加多个条件
Dim cond As New GroupOperator
Dim oper1 As New BinaryOperator(New OperandProperty("F1400"), New OperandValue(2), BinaryOperatorType.Greater)
Dim oper2 As New BinaryOperator(New OperandProperty("F1401"), New OperandValue(1), BinaryOperatorType.Equal)
cond = New GroupOperator(GroupOperatorType.And, oper1, oper2)
Dim Collection1 As New XPCollection(GetType(F_ExitInterview), cond)
DataGrid1.DataSource = Collection1
DataGrid1.DataBind()
6.表关系为一对多的实现方法.
[Aggregated] 没有参数
实现两个持久类的级联删除的功能,简单地说就是如果加上Aggregated参数,那么删除主表的时记录时一同连子表的记录也都删除了,如果不加那么必须把子表的数据全部删除才可以删除主表的记录.
例子:
有一个主表 V_CommonReview 和一个子表V_Exit
主表V_CommonReview 主键为V0900
子表V_Exit 主键为V0600 外鍵为V0627
一条V_CommonReview表中记录对应多条子表V_Exit的记录
那么为了实现级联关系那么先在子表V_Exit定义一个外鍵为V0627
类型为V_CommonReview对象类型.
<Association("V_ExitCommonReview")> Public V0627 As V_CommonReview
然后在V_CommonReview表中定义
<Association("V_ExitCommonReview", GetType(V_Exit))> _
Public ReadOnly Property V_exits() As XPCollection
Get
Return GetCollection("V_exits")
End Get
End Property
注:V_ExitCommonReview为关系名称,起什么都可以
做完这步了就可以把子表当作一个数据库中的视图显示两个表中的记录了
例如:
(1) 下面是实现关联表数据集合的显示功能.
Dim x As New XPCollection(GetType(V_Exit))
x.DisplayableProperties = "V0627.V0900;V0627.V0901;V0627.V0902"
DataGrid1.DataSource = x
DataGrid1.DataBind()
默认情况下如果设置DataGrid的自动生成列属性为真,那么把子表的内容全都显示出来,但你可以通过设置XPCollection的DisplayableProperties属性来设置想要显示的主表中的字段.
(2) 下面是实现关联表单条数据的增加和保存功能.
Dim bizObject As V_Exit
If CheckIsEdit() Then
bizObject = New XPCollection(GetType(V_Exit), New BinaryOperator("V0602", CInt(Session("VOLUNTEERID")), BinaryOperatorType.Equal)).Object(0)
Else
bizObject = New V_Exit
End If
With bizObject
'.V0601 = ddlV0601.SelectedValue
.V0602 = CInt(Session("VOLUNTEERID"))
.V0603 = txtV0603.Text
.......
If .V0627 Is Nothing Then '----这里.V0627是一个类对象
Dim CR As New V_CommonReview
With CR
.V0901 = ddlV0901.SelectedValue
.V0919 = txtV0919.Text
.V_exits.Add(bizObject)
.Save()
End With
Else
.V0627 = New XPCollection(GetType(V_CommonReview), New BinaryOperator("V0900", .V0627.V0900, BinaryOperatorType.Equal)).Object(0)
.V0627.V0901 = ddlV0901.SelectedValue
.V0627.V0919 = txtV0919.Text
.V0627.V_exits.Add(bizObject)
.Save()
End If
End With
只需保存主表的内容,把子表的域都赋值,那么子表的内容自动保存
(3) 下面是实现关联表单条数据的显示功能.
在Load数据时也要先判断一下外键是否为空,然后在Load主表信息
Dim bizObject As V_Exit
If CheckIsEdit() Then
bizObject = New XPCollection(GetType(V_Exit), New BinaryOperator("V0602", CInt(Session("VOLUNTEERID")), BinaryOperatorType.Equal)).Object(0)
Else
Return
End If
With bizObject
txtV0603.Text = .V0603
If Not .V0627 Is Nothing Then
ddlV0901.SelectedValue = .V0627.V0901
ddlV0902.SelectedValue = .V0627.V0902
End If
End With
7.直接通过传SQL语句获得对象集合的方法!
Dim command As IDbCommand
Dim reader As IDataReader
command = DevExpress.Xpo.Session.DefaultSession.ConnectionProvider.CreateCommand()
command.CommandText = "Select * from VS_Service where F0302=2"
reader = command.ExecuteReader()
DataGrid1.DataSource = reader
DataGrid1.DataBind()
reader.Close()
8.删除一条记录的写法
Dim bizobject As New F_FamilyService
bizobject = New XPCollection(GetType(F_FamilyService), New
BinaryOperator("F0300", editID,
BinaryOperatorType.Equal)).Object(0)
bizobject.Delete()
注:F0300为F_FamilyService表的主键
