在后台怎样修改数据源的"whereClause"

以下是使用了WEB的数据源控件:

在aspx页面是这样的:
     一般情况下,.nettiers是生成这样的代码:(请注意是"CustomParameter")

 

 

<data:EmployeesDataSource 

   <Parameters>
    <data:CustomParameter Name="WhereClause"../>
  </Parameters>
</data:EmployeesDataSource>

 

然而要实现后台修改数据源的"whereClause",则要把<data:CustomParameter  Value="Country='USA'"...> 改为
  <data:SqlParameter DefaultValue="Country='USA'"...> , 在这种情况下Value不可用,只会有DefaultValue,但DefaultValue没有选出相应记录的功能.

 

<data:EmployeesDataSource id="EmployeesDataSource" runat="server" EnableDeepLoad="True" EnableSorting="True" EnablePaging="True" SelectMethod="GetPaged">
            <DeepLoadProperties Method="IncludeChildren" Recursive="False">
                <Types>
                    <data:EmployeesProperty Name="Employees" /> 
                    <%--<data:EmployeesProperty Name="OrdersCollection" />--%>
                    <%--<data:EmployeesProperty Name="EmployeesCollection" />--%>
                    <%--<data:EmployeesProperty Name="EmployeeTerritoriesCollection" />--%>
                    <%--<data:EmployeesProperty Name="TerritoryIdTerritoriesCollection_From_EmployeeTerritories" />--%>
                </Types>
            </DeepLoadProperties>
            <Parameters>
                <data:SqlParameter Name="WhereClause" ConvertEmptyStringToNull="false" UseParameterizedFilters="false" />
                <data:SqlParameter Name="OrderByClause"  ConvertEmptyStringToNull="false"  />
                <asp:ControlParameter Name="PageIndex" ControlID="GridView1" PropertyName="PageIndex" Type="Int32" ></asp:ControlParameter>
                <asp:ControlParameter Name="PageSize" ControlID="GridView1" PropertyName="PageSize" Type="Int32" ></asp:ControlParameter>
                <data:SqlParameter Name="RecordCount" Type="Int32"  />
            </Parameters>
</data:EmployeesDataSource>

 

后台代码:

 

EmployeesExpressionBuilder parameter = new EmployeesExpressionBuilder();
parameter.Column = EmployeesColumn.HireDate;
parameter.BuilderExpression = StringBuilderExpression.AppendEquals;
parameter.DefaultValue = this.TextBox1.Text;

(EmployeesDataSource.Parameters[0] as SqlParameter).Filters.Add(parameter);

 

以下是通过时间范围修改whereclause:

 protected void Page_Load(object sender, EventArgs e)
    {

        EmployeesExpressionBuilder parameter = new EmployeesExpressionBuilder();
        parameter.Column = EmployeesColumn.Country;
        parameter.BuilderExpression = StringBuilderExpression.AppendEquals;
        parameter.DefaultValue = "USA";

        (EmployeesDataSource.Parameters[0] as SqlParameter).Filters.Add(parameter);

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        EmployeesExpressionBuilder parameter1 = new EmployeesExpressionBuilder();
        parameter1.Column = EmployeesColumn.HireDate;
        parameter1.BuilderExpression = StringBuilderExpression.AppendGreaterThanOrEqual;
        parameter1.DefaultValue = this.TextBox1.Text;

        EmployeesExpressionBuilder parameter2 = new EmployeesExpressionBuilder();
        parameter2.Column = EmployeesColumn.HireDate;
        parameter2.BuilderExpression = StringBuilderExpression.AppendLessThanOrEqual;
        parameter2.DefaultValue = this.TextBox2.Text;

        (EmployeesDataSource.Parameters[0] as SqlParameter).Filters.Add(parameter1);
        (EmployeesDataSource.Parameters[0] as SqlParameter).Filters.Add(parameter2);

        //************************************************************************************************************
        //查询方法五:
        //SqlFilterBuilder<EmployeesColumn> sqlfilter = new SqlFilterBuilder<EmployeesColumn>();
        //sqlfilter.AppendRange(EmployeesColumn.HireDate, this.TextBox1.Text, this.TextBox2.Text);
        //int cnt = 0;
        //TList<Employees> List = DataRepository.EmployeesProvider.GetPaged(sqlfilter.ToString(), null, 0, 20, out cnt);
        //this.GridView1.DataSource = List;
        //this.GridView1.DataBind();
        //“GridView1”上同时定义了 DataSource 和 DataSourceID。请移除一个定义。
       
    }
}

 

又或者直接在ASPX页面是修改WhereClause:

  

Code
<data:EmployeesDataSource id="EmployeesDataSource" runat="server" EnableDeepLoad="True" EnableSorting="True" EnablePaging="True" SelectMethod="GetPaged">
            <DeepLoadProperties Method="IncludeChildren" Recursive="False">
                <Types>
                    <data:EmployeesProperty Name="Employees" /> 
                    <%--<data:EmployeesProperty Name="OrdersCollection" />--%>
                    <%--<data:EmployeesProperty Name="EmployeesCollection" />--%>
                    <%--<data:EmployeesProperty Name="EmployeeTerritoriesCollection" />--%>
                    <%--<data:EmployeesProperty Name="TerritoryIdTerritoriesCollection_From_EmployeeTerritories" />--%>
                < pes>
            </DeepLoadProperties>
            <Parameters>
                <data:CustomParameter Name="WhereClause" Value="Country='USA'" ConvertEmptyStringToNull="false"  />
                <data:CustomParameter Name="OrderByClause" Value="EmployeeId DESC" ConvertEmptyStringToNull="false"  />
                <asp:ControlParameter Name="PageIndex" ControlID="GridView1" PropertyName="PageIndex" Type="Int32" ></asp:ControlParameter>
                <asp:ControlParameter Name="PageSize" ControlID="GridView1" PropertyName="PageSize" Type="Int32" ></asp:ControlParameter>
                <data:CustomParameter Name="RecordCount" Value="0" Type="Int32"  />
            </Parameters>
        </data:EmployeesDataSource>

 

 

以上问题总结如下:

1.<data:CustomParameter...> 与
  <data:SqlParameter...>  SqlParameter,CustomParameter主要区别是?

 

2.用了<data:SqlParameter...> 就不能用      Value="Country='USA'",那么我要页面加载的时候是不是要在 Page_Load事件中写同类似的事件?

 答:可以在Page_Load事件中写入

EmployeesExpressionBuilder parameter = new EmployeesExpressionBuilder();
parameter.Column = EmployeesColumn.Country;
parameter.BuilderExpression = StringBuilderExpression.AppendEquals;
parameter.DefaultValue = "USA";

(EmployeesDataSource.Parameters[0] as SqlParameter).Filters.Add(parameter);

 

3.(EmployeesDataSource.Parameters[0] as SqlParameter).Filters.Add(parameter);这句它就会自动地绑定.

 

4.记得加上UseParameterizedFilters="false" !!!!

 

5.http://www.cnblogs.com/iCaca/archive/2007/07/10/812632.html  前台可参考这里,还要感谢icaca的帮忙!