Bug report

Using Array.prototype adds items to FIlter fields DropDownLists

Reproduction of the problem

Open below Dojo and run it.

https://dojo.telerik.com/izABOFaf/2

Open Featured DDL. The result is

Expected/desired behavior

Using Array.prototype shall not add items to the DDL

Environment
Kendo UI version: [all]
jQuery version: x.y
Browser: [all]

Based on your demos (https://demos.telerik.com/kendo-ui/filter/index), it seems it is impossible to get the filter control to use localized messages just by loading the required language file (other controls seems to switch language OK).   Whilst it is possible to have completely custom text using the configuration api, it should still be possible to have defaults for the main languages supported.

When using the Filter control and configuring the Fields, if a 'number' type field is used, the value 0 (zero) is ignored, for example:

$("#filter").kendoFilter({
    dataSource: dataSource,
    expressionPreview: true,
    fields: [
      { name: "age", type:"number", defaultValue: 31 },
      {name: "foo", type: "number", defaultValue: 0},
      { name: "name", type:"string", defaultValue: "Rick" }
    ]
  });

'age' and 'foo' are both 'number' type fields, but the default value of 'foo' will be ignored when the filter is chosen in the UI.

 

Here is a runnable example of this, notice how when selecting 'age' from the fields dropdown, the value correctly defaults to 31, but selecting the 'foo' field will not have the value populate correctly:

https://dojo.telerik.com/eHAROSOz

There are occasions when the out-of-the-box filter operators can't be used, such as filtering on nested objects. In these situations I use a custom function for the filter operator.

It would be great if the Filter widget could support custom filter operators.

I realise this would be challenging, as it would break the save/load state function and would be difficult to handle in the expressionPreview.

Reproduction of the problem

1. Open dojo at https://dojo.telerik.com/@GaloisGirl/AqotEtep
2. Click "Add expression" and pick "Product name",  "Is not equal to", "".
   
3. Click "Apply". The grid show 77 items, as expected.
4. Click "Add group" and then "Apply".
   

Current behavior

The grid shows 0 items. The expression preview is (Product Name Is not equal to '').

Expected/desired behavior

The grid should show 77 items. For an optimal user experience, the empty groups should be deleted when applying the filter.

Hi Team,

When a date filter is applied in the new Filter widget, the preview looks like: "Date Is After 'Tue Jan 01 2019 00:00:00 GMT+0000 (Greenwich Mean Time)'" -- I'd like to be able to customize the displayed date format, something like adding "format:"{0:dd/MM/yyyy}" to the 'fields' object.

Thanks