c# - 带有 ObjectDatasource UpdateMethod 的 GridView

Question

我有一个包含 ASPxGridView 和 ObjectDataSource 的 ASP.NET WebForms 页面:

<dx:ASPxGridView ID="gvEmployees" runat="server"
    AutoGenerateColumns="False" DataSourceID="objDsEmployees"
    KeyFieldName="EmployeeId">
    <Columns>
        <dx:GridViewCommandColumn VisibleIndex="0">
            <EditButton Visible="True" />
        </dx:GridViewCommandColumn>
        <dx:GridViewDataTextColumn FieldName="EmployeeId" VisibleIndex="1" />
        <dx:GridViewDataTextColumn FieldName="Name" VisibleIndex="2" />
        <dx:GridViewDataTextColumn FieldName="Email" VisibleIndex="3" />
        <dx:GridViewDataTextColumn FieldName="Telephone" VisibleIndex="5" />
    </Columns>
</dx:ASPxGridView>
<asp:ObjectDataSource ID="objDsEmployees"
    runat="server"
    ConflictDetection="CompareAllValues"
    DataObjectTypeName="MySite.Data.Models.Employee"
    DeleteMethod="Delete"
    OldValuesParameterFormatString="original{0}"
    InsertMethod="Insert"
    SelectMethod="GetAll"
    TypeName="MySite.Services.EmployeeService"
    UpdateMethod="Update" />

Employee 模型包含以下属性:

public class Employee
{
    public int EmployeeId { get; set; }

    public string Name { get; set; }

    public string Email { get;

    public string Password { get; set; }

    public string Telephone { get; set; }
}

ObjectDataSource调用服务层的Update方法:

public void Update(Employee employee, Employee originalEmployee)
{
    _db.Employees.Attach(originalEmployee);
    _db.Entry(originalEmployee).CurrentValues.SetValues(employee);
    _db.SaveChanges();
}

调用Update 方法时，参数employee 和originalEmployee 仅包含在ASPxGridView< 中用作列的属性 和其他属性(例如 Password)为空。

有什么方法可以将这些值保存在某处吗？顺便说一句，我使用 Entity Framework 进行数据访问，使用 DevExpress 进行 GridView。

Answer 1

您还可以通过在 ObjectDataSource 中设置 ConflictDetection="CompareAllValues" 来解决此问题:

<asp:ObjectDataSource ID="objDsEmployees"
    runat="server"
    DeleteMethod="Delete"
    InsertMethod="Insert"
    SelectMethod="GetAll"
    UpdateMethod="Update"
    DataObjectTypeName="App.Core.Domain.Employee"
    TypeName="App.Core.Services.EmployeeService"
    OldValuesParameterFormatString="original{0}"
    ConflictDetection="CompareAllValues" />

然后在 EmployeeService 的 Update 方法中，我们首先通过其 id 获取原始员工，然后我们将这个原始员工与更新后的员工合并。这确保未更新的属性不会变为 null - 尽管它需要额外调用数据库:

public void Update(Employee originalEmployee, Employee employee)
{
    // Get the original employee by its id.
    Employee fullOriginalEmployee = GetById(originalEmployee.EmployeeId);

    // Merge the data of the updated employee with the original employee.
    fullOriginalEmployee.Name = employee.Name;
    fullOriginalEmployee.Email = employee.Email;
    fullOriginalEmployee.Telephone = employee.Telephone;
    fullOriginalEmployee.BirthDate = employee.BirthDate;

    // Persist changes in database.
    SaveChanges();
}