Kentico UniGrid中的GridView的DataBound

kentico12\UIControls\Controls\UniGrid\UniGrid.cs

protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);

            AdvancedExportControl.UniGrid = this;

            PageSizeDropdown.SelectedIndexChanged += PageSizeDropdown_SelectedIndexChanged;
            GridView.Sorting += GridView_Sorting;
            GridView.DataBinding += GridView_DataBinding;
            GridView.DataBound += GridView_DataBound;
            GridView.RowCreated += GridView_RowCreated;
        }

还有下面两个成员

  /// <summary>
        /// Selection external source name. Used for external DataBound of selection column.
        /// </summary>
        public const string SELECTION_EXTERNAL_DATABOUND = "UG_Selection_DataBound";


        /// <summary>
        /// Select all external source name. Used for header external DataBound of SelectAll check box.
        /// </summary>
        public const string SELECTALL_EXTERNAL_DATABOUND = "UG_SelectAll_DataBound";

kentico12\UIControls\Controls\UniGrid\Fields\GridViewTemplate.cs   在这个GridViewTemplate中，BindCheckData

  /// <summary> 
        /// Handle DataBinding event called in the InstantiateIn method.
        /// </summary>        
        private void BindCheckData(object sender, EventArgs e)
        {
            CMSCheckBox checkBox = (CMSCheckBox)sender;
            GridViewRow container = (GridViewRow)checkBox.NamingContainer;

            var uniGrid = UniGridControl;

            if (container.RowType == DataControlRowType.DataRow)
            {
                if (container.DataItem != null)
                {
                    var dataItem = (DataRowView)container.DataItem;

                    var selColumn = checkBox.Attributes["selectioncolumn"];

                    string argument = String.IsNullOrEmpty(selColumn) ? dataItem[0].ToString() : dataItem[selColumn].ToString();

                    if (uniGrid != null)
                    {
                        // Add to the allowed selection
                        uniGrid.SelectionsID.Add(argument);

                        checkBox.Page.PreRenderComplete += ((senderObj, eventArgs) => { if (uniGrid.SelectedItems != null) { checkBox.Checked = uniGrid.SelectedItems.Contains(argument, StringComparer.InvariantCultureIgnoreCase); } });

                        string onclick = uniGrid.GetJSModule() + ".select(this);";

                        checkBox.InputAttributes["data-arg"] = argument;
                        checkBox.InputAttributes["data-argHash"] = ValidationHelper.GetHashString(argument, HashSettings);

                        if (!String.IsNullOrEmpty(uniGrid.SelectionJavascript))
                        {
                            onclick += $"{uniGrid.SelectionJavascript}('{ScriptHelper.GetString(argument, false)}', this.checked);";
                        }

                        checkBox.InputAttributes["onclick"] = onclick;
                        checkBox.InputAttributes["onchange"] = uniGrid.GetJSModule() + ".updateHeaderCheckbox();";

                        uniGrid.RaiseExternalDataBound(checkBox, UniGrid.SELECTION_EXTERNAL_DATABOUND, container.DataItem);
                    }

                    checkBox.Attributes.Remove("selectioncolumn");
                }
            }
            else if (container.RowType == DataControlRowType.Header)
            {
                if (uniGrid != null)
                {
                    checkBox.Attributes["onclick"] = uniGrid.GetJSModule() + ".selectAll(this);";
                    checkBox.Checked = false;

                    uniGrid.RaiseExternalDataBound(checkBox, UniGrid.SELECTALL_EXTERNAL_DATABOUND, container.DataItem);
                }
            }
        }

kentico12\UIControls\Controls\UniGrid\UniGrid.cs

/// <summary>
        /// Raises the external data bound event.
        /// </summary>
        /// <param name="sender">Sender object</param>
        /// <param name="sourceName">External source name</param>
        /// <param name="parameter">Source parameter</param>
        public object RaiseExternalDataBound(object sender, string sourceName, object parameter)
        {
            // Special handling for built-in grid transformations
            if ((sourceName != null) && (sourceName[0] == '#'))
            {
                // Object transformation
                if (sourceName.StartsWith(UniGridTransformations.TRANSFORM_PREFIX, StringComparison.OrdinalIgnoreCase))
                {
                    int prefixLength = UniGridTransformations.TRANSFORM_PREFIX.Length;

                    int trIndex = sourceName.IndexOf(':', prefixLength);
                    if (trIndex <= 0)
                    {
                        // Search for the last part (column name)
                        trIndex = sourceName.LastIndexOf(".", StringComparison.Ordinal);
                    }

                    if (trIndex > 0)
                    {
                        int objectId;

                        string objectType = sourceName.Substring(prefixLength, trIndex - prefixLength).Trim();
                        string columnName = sourceName.Substring(trIndex + 1).Trim();

                        if (parameter is DataRowView)
                        {
                            // ##ALL##
                            int lIndex = objectType.IndexOf("=>", StringComparison.Ordinal);
                            if (lIndex <= 0)
                            {
                                return null;
                            }

                            string idValue = objectType.Substring(lIndex + 2).Trim();
                            objectType = objectType.Substring(0, lIndex).Trim();

                            // Resolve macros in object type and ID value
                            CurrentResolver.SetAnonymousSourceData(parameter);

                            idValue = CurrentResolver.ResolveMacros(idValue);
                            objectType = CurrentResolver.ResolveMacros(objectType);

                            objectId = ValidationHelper.GetInteger(idValue, 0);
                        }
                        else
                        {
                            // Specific column (ID of the object)
                            objectId = ValidationHelper.GetInteger(parameter, 0);
                        }

                        if (objectId <= 0)
                        {
                            return null;
                        }

                        // Add the field transformation control that handles the translation
                        var tr = new ObjectTransformation(objectType, objectId);
                        tr.Transformation = columnName;

                        return tr;
                    }
                }

                // Try to find the transformation
                if (UniGridTransformations.Global.ExecuteTransformation(sender, sourceName, ref parameter))
                {
                    return parameter;
                }
            }

            // If column was added using AddAdditionalColumn method and its external data bound callback was specified, fire it
            OnExternalDataBoundEventHandler additionalExternalDataBound;
            if (TryGetAdditionalExternalDataBoundCallback(sourceName, out additionalExternalDataBound))
            {
                return additionalExternalDataBound(sender, sourceName, parameter);
            }

            return OnExternalDataBound?.Invoke(sender, sourceName, parameter);
        }

应该是执行了后半部分

// If column was added using AddAdditionalColumn method and its external data bound callback was specified, fire it
            OnExternalDataBoundEventHandler additionalExternalDataBound;
            if (TryGetAdditionalExternalDataBoundCallback(sourceName, out additionalExternalDataBound))
            {
                return additionalExternalDataBound(sender, sourceName, parameter);
            }

            return OnExternalDataBound?.Invoke(sender, sourceName, parameter);