DxTreeList.CustomizeEditModel Event

Allows you to customize an automatically generated edit model or create a custom edit model.

Assembly : DevExpress.Blazor.v25.2.dll

Declaration

csharp

[Parameter]
public EventCallback<TreeListCustomizeEditModelEventArgs> CustomizeEditModel { get; set; }

Parameters

Type	Description
TreeListCustomizeEditModelEventArgs

An object that contains data for this event.

Remarks

Once a user starts editing a row, the TreeList creates a clone of the edited data item – an edit model. Handle the CustomizeEditModel event to initialize the edit model for new data rows. In the event handler, you can also customize an automatically generated edit model or create a custom edit model.

Read Tutorial: Edit Model Read Tutorial: Edit Data Run Demo: Edit Data

Initialize New Rows

Follow the steps below to initialize an edit model for new data rows:

Handle the CustomizeEditModel event.
Check the IsNew event argument to identify new rows.
Use EditModel and ParentDataItem arguments to link a new node to its parent.
(Optional) Use the EditModel event argument to initialize model fields with predefined values.

The following snippet initializes an edit model for new tasks:

Razor
EmployeeTask.cs
EmployeeTaskService.cs
Program.cs

razor

@inject EmployeeTaskService EmployeeTaskService

<DxTreeList Data="TreeListData"
            KeyFieldName="Id"
            ParentKeyFieldName="ParentId"
            EditModelSaving="TreeList_EditModelSaving"
            DataItemDeleting="TreeList_DataItemDeleting"
            CustomizeEditModel="TreeList_CustomizeEditModel">
    <Columns>
        <DxTreeListCommandColumn />
        <DxTreeListDataColumn FieldName="Name" Caption="Task" />
        <DxTreeListDataColumn FieldName="EmployeeName" />
        <DxTreeListDataColumn FieldName="StartDate" />
        <DxTreeListDataColumn FieldName="DueDate" />
    </Columns>
</DxTreeList>

@code {
    List<EmployeeTask> TreeListData { get; set; }

    protected override void OnInitialized() {
        TreeListData = EmployeeTaskService.GenerateData();
    }
    void TreeList_CustomizeEditModel(TreeListCustomizeEditModelEventArgs e) {
        if(e.IsNew) {
            var newTask = (EmployeeTask)e.EditModel;
            newTask.Id = TreeListData.Max(x => x.Id) + 1;
            newTask.Name = "New task";
            newTask.StartDate = DateTime.Today;
            newTask.DueDate = DateTime.Today.AddDays(7);
            if(e.ParentDataItem != null)
                newTask.ParentId = ((EmployeeTask)e.ParentDataItem).Id;
        }
    }
    async Task TreeList_EditModelSaving(TreeListEditModelSavingEventArgs e) {
        if(e.IsNew)
            TreeListData.Add((EmployeeTask)e.EditModel);
        else
            e.CopyChangesToDataItem();
    }
    async Task TreeList_DataItemDeleting(TreeListDataItemDeletingEventArgs e) {
        TreeListData.Remove((EmployeeTask)e.DataItem);
    }
}

csharp

public class EmployeeTask {
    public int Id { get; set; }
    public int ParentId { get; set; }
    public string Name { get; set; }
    public string EmployeeName { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime DueDate { get; set; }
    public int Progress { get; set; }
    public EmployeeTask() { }
    public EmployeeTask(
        int id,
        int parentId,
        string name,
        string employeeName,
        DateTime startDate,
        DateTime dueDate,
        int progress
        )
    {
        Id = id;
        ParentId = parentId;
        Name = name;
        EmployeeName = employeeName;
        StartDate = startDate;
        DueDate = dueDate;
        Progress = progress;
    }
}

csharp

public class EmployeeTaskService {
    public List<EmployeeTask> GenerateData() {
        return new List<EmployeeTask>() {
            new EmployeeTask(1, 0, "Simplify & Clarify Product Messaging", "John Heart", new DateTime(2018, 4, 3), new DateTime(2018, 4, 14), 14),
            new EmployeeTask(2, 1, "Prepare Financial Reports", "Samantha Bright", new DateTime(2018, 4, 3), new DateTime(2018, 4, 7), 17),
            new EmployeeTask(3, 1, "Prepare Marketing Plan", "Arthur Miller", new DateTime(2018, 4, 7), new DateTime(2018, 4, 14), 11),
            new EmployeeTask(4, 0, "Create Action Plan to Improve Customer Engagement", "Robert Reagan", new DateTime(2017, 8, 8), new DateTime(2018, 4, 8), 23),
            new EmployeeTask(5, 4, "Update Personnel Files", "Greta Sims", new DateTime(2017, 8, 8), new DateTime(2017, 10, 18), 100),
            new EmployeeTask(6, 4, "Review Health Insurance Options", "Brett Wade", new DateTime(2017, 9, 27), new DateTime(2017, 11, 10), 37),
            new EmployeeTask(7, 4, "Choose Between PPO and HMO Health Plan", "Sandra Johnson", new DateTime(2017, 12, 13), new DateTime(2018, 3, 23), 17),
            new EmployeeTask(8, 4, "Update Google Adwords Strategy", "Ed Holmes", new DateTime(2017, 8, 23), new DateTime(2017, 12, 23), 45),
            new EmployeeTask(9, 4, "Create New Brochure Design", "Barb Banks", new DateTime(2018, 1, 3), new DateTime(2018, 3, 14), 17),
            new EmployeeTask(10, 4, "Obtain Price Quote for New Brochure", "Kevin Carter", new DateTime(2018, 2, 1), new DateTime(2018, 3, 15), 18),
            new EmployeeTask(11, 4, "Brochure Design Review", "Cindy Stanwick", new DateTime(2017, 8, 22), new DateTime(2017, 10, 28), 4),
            new EmployeeTask(12, 4, "Review Website Redesign Strategy", "Sammy Hill", new DateTime(2017, 9, 16), new DateTime(2018, 3, 6), 73),
            new EmployeeTask(13, 4, "Roll Out New Website", "Davey Jones", new DateTime(2017, 11, 7), new DateTime(2018, 2, 6), 9),
            new EmployeeTask(14, 4, "Update Sales/Marketing Strategy", "Victor Norris", new DateTime(2017, 12, 13), new DateTime(2018, 4, 2), 5),
            new EmployeeTask(15, 4, "Update Sales/Revenue Report", "Mary Stern", new DateTime(2017, 12, 25), new DateTime(2018, 4, 2), 4),
            new EmployeeTask(16, 4, "Direct vs Online Sales Comparison Report", "Robin Cosworth", new DateTime(2018, 1, 2), new DateTime(2018, 3, 20), 14),
            new EmployeeTask(17, 4, "Review Sales Report and Approve Modifications", "Kelly Rodriguez", new DateTime(2017, 9, 4), new DateTime(2017, 10, 30), 8),
            new EmployeeTask(18, 4, "Update R&D Strategy", "James Anderson", new DateTime(2017, 11, 13), new DateTime(2017, 12, 4), 12),
            new EmployeeTask(19, 4, "Discuss Updated R&D Strategy", "Antony Remmen", new DateTime(2017, 10, 29), new DateTime(2017, 12, 31), 14),
            new EmployeeTask(20, 4, "Update QA Strategy", "Olivia Peyton", new DateTime(2017, 10, 31), new DateTime(2017, 11, 2), 18),
            new EmployeeTask(21, 4, "Schedule Training Events", "Taylor Riley", new DateTime(2017, 11, 19), new DateTime(2018, 4, 7), 21),
            new EmployeeTask(22, 4, "Approve Hiring of John Jeffers", "Amelia Harper", new DateTime(2018, 1, 7), new DateTime(2018, 4, 8), 10),
            new EmployeeTask(23, 0, "Increase Average Subscription Price", "Wally Hobbs", new DateTime(2017, 8, 9), new DateTime(2017, 9, 13), 96),
            new EmployeeTask(24, 23, "Update Non-Compete Agreements", "Brad Jameson", new DateTime(2017, 8, 9), new DateTime(2017, 9, 3), 96),
            new EmployeeTask(25, 23, "Update Employee Records with New NDA", "Karen Goodson", new DateTime(2017, 8, 23), new DateTime(2018, 9, 10), 100)
        };
    }
}

csharp

// ...
builder.Services.AddSingleton<EmployeeTaskService>();

Create a Custom Edit Model

The TreeList component cannot generate an edit model in the following cases:

A data item class does not have a parameterless constructor.
Data item fields bound to TreeList columns are read-only.
In a hierarchical data source, a data type of children nodes differs from the parent node’s data type. In this case, the TreeList cannot determine which data type to use for new rows and generates edit models only for existing rows.

You can create a custom edit model or customize an automatically generated edit model as follows:

Handle the CustomizeEditModel event.
Use the DataItem event argument to access the processed data item. Note that the data item is null for new rows.
Assign your custom edit model to the EditModel event argument.

When you obtain an EditModel object in event handlers or edit templates, cast this object to your custom edit model class as shown below:

razor

<DxTreeList Data="TreeListData"
            KeyFieldName="Id"
            ParentKeyFieldName="ParentId"
            EditMode="TreeListEditMode.EditForm"
            EditModelSaving="TreeList_EditModelSaving"
            DataItemDeleting="TreeList_DataItemDeleting"
            CustomizeEditModel="TreeList_CustomizeEditModel">
    <Columns>
        <DxTreeListCommandColumn />
        <DxTreeListDataColumn FieldName="Name" Caption="Task" />
        <DxTreeListDataColumn FieldName="EmployeeName" />
        <DxTreeListDataColumn FieldName="StartDate" />
        <DxTreeListDataColumn FieldName="DueDate" />
    </Columns>
    <EditFormTemplate Context="editFormContext">
        @{ 
            var editModel = (EmployeeTaskEditModel)editFormContext.EditModel; 
        }
        @* ... *@
    </EditFormTemplate>
</DxTreeList>

@code {
    List<EmployeeTask> TreeListData { get; set; }

    class EmployeeTaskEditModel {
        public int Id { get; set; }
        public int ParentId { get; set; }
        [Required]
        public string Name { get; set; }
        public string EmployeeName { get; set; }
        public DateTime StartDate { get; set; }
        [Required]
        [Range(typeof(DateTime), "1/12/2016", "1/12/2025", ErrorMessage = "DueDate must be between {1:d} and {2:d}")]
        public DateTime DueDate { get; set; }
    }
    async Task TreeList_EditModelSaving(TreeListEditModelSavingEventArgs e) {
        var editModel = (EmployeeTaskEditModel)e.EditModel;
    }
    void TreeList_CustomizeEditModel(TreeListCustomizeEditModelEventArgs e) {
        if(e.IsNew) {
            var newTask = new EmployeeTaskEditModel { };
            newTask.Id = TreeListData.Max(x => x.Id) + 1;
            newTask.Name = "New task";
            newTask.StartDate = DateTime.Today;
            newTask.DueDate = DateTime.Today.AddDays(7);
            e.EditModel = newTask;
        }
        else {
            var dataItem = (EmployeeTask)e.DataItem;
            e.EditModel = new EmployeeTaskEditModel {
                Id = dataItem.Id,
                ParentId = dataItem.ParentId,
                Name = dataItem.Name,
                EmployeeName = dataItem.EmployeeName,
                StartDate = dataItem.StartDate,
                DueDate = dataItem.DueDate
            };
        }
    }
    // ...
}

Edit Data with Nested Properties

When you edit data, the TreeList clones a bound data item – namely creates an object of the same type and copies all property values into it. If a property is of a reference type, the reference is copied but the referred object is not copied. As the result, the original object and its clone refer to the same object.

To edit nested objects, create a copy of these objects manually (make a deep copy of the original data item object). You can use the following approaches to implement a deep copy operation:

Handle the CustomizeEditModel event, clone the nested object, and assign it to field whose value is the reference type.
Create constructors for the data item type and the nested object’s type. In the data item type constructor, the nested object type constructor clones the nested object with its property values. Handle the CustomizeEditModel event and call a data item’s class constructor to initialize the edit model.