Scoping issues while using context menu

问题

I'm following the docs here to add a context menu item to my grid. The issue is that from the scope of getContextMenuItems (in the example), I'm unable to access any other methods or variables in my component. Is this possible? Example below:

private varIWantToAccess: boolean = false;

function getContextMenuItems(params) {
    var result = [
    { // custom item
        name: 'Alert ' + params.value,
        action: function () 
    {
        window.alert('Alerting about ' + params.value);
        this.varIWantToAccess = true; // Builds fine, but throws a run time exception, since this "this" context is different than the one that has "varIWantToAccess"
    }
    },
        ....
        return result;
}

Thanks!

回答1:

I assume that you are speaking of an Angular 2 or 4 component using TypeScript. If so then use fat arrow to connect to your function.

Example:

gridOptions.getContextMenuItems = () => this.getContextMenuItems();

This should provide you the scope you need.

回答2:

You can add the reference to this in grid's context -

this.gridOptions.context = {
                    thisComponent : this
                };

And then, thisComponent can be access as below -

private getContextMenuItems(params) { 
    console.log(params);
    var result = [
        { // custom item
            name: 'Sample',
            action: function () {params.context.thisComponent.callMe();  },
            icon: '<i class="fa fa-pencil" />'
        }];
    return result;
}

Same can be done for any other call backs like cellRenderer.

回答3:

You need to provide parent context property to the item. Sample context menu item:

{ name: 'BreakoutReport', action: function () { this.context.isDrillDownData = false; this.context.isBreakOutReport = true; this.context.populateBreakOutGrid(); }, cssClasses: ['redFont', 'bold'], disabled: !params.value.drillDownReport, context: params.context }

Here, this.context has access to all the parent functions. Remeber, this context needs to be set in grid options first and then can be transferred to context menu items.

1st step: set context in gridOptions

 getGridOption() {
            return {
                getContextMenuItems: this.getContextMenu,
                context: this//pass parent context
            };
        }

2nd step: pass context to context menu subitems

  getContextMenu(params) {
    const result = [
         {
            name: 'Drilldown Report',
            action: function () {
                this.context.populateDrillDownReport();//access parent context using this.context inside the function.
            },
            cssClasses: ['redFont', 'bold'],
            disabled: !params.value.drillDownReport,
            context: params.context//pass parent context
        },
        'separator',
        'copy',
        'copyWithHeaders'];
    return result;
}

来源：https://stackoverflow.com/questions/42680019/scoping-issues-while-using-context-menu