UMG Viewmodel Plugin -- When setting up View Bindings, several arithmetic and comparison functions are missing from the "Conversion Functions" list

When setting up View Bindings from the "UMG Viewmodel Plugin" on a Widget Blueprint, it is possible to select a compatible "Conversion Function" from the list of available bindings. By default, the Conversion Function list is populated from the "Blueprint Action Registry", and the candidate functions are filtered based on input/output type compatibility.

When Blueprint Type Promotion is enabled (which is by default), typed Blueprint Math Nodes such as arithmetic operations (+, *, /) and comparison operators (<, >, ==) are excluded from the Blueprint Action Registry in favor of Promotable Operators, which have wildcard input and output pins. However, Promotable Operators are not considered eligible as Conversion Functions for View Bindings. As a result, the Conversion Function list ends up not including any of these important arithmetic/comparison math operations, which is perceived as a bug.

Besides turning off Blueprint Type Promotion, another workaround is to set "Conversion Function Filter" = "Conversion Function Library" instead of "Blueprint Action Registry" in the Project settings.

1. Make sure that plugin "UMG Viewmodel" is enabled

2. Create a new Blueprint Class based on MVVMViewModelBase

2.1. Add a new Integer variable "MyInteger"

2.2. Add a new Float variable "MyFloat"

2.3. Compile, save, close

3. Create a new Widget Blueprint based on User Widget

4. Open the new widget asset. In the Designer mode:

4.1. Open the "Viewmodels" tab ("Window – Viewmodels")

4.1.1. Click "Add Viewmodel" (plus icon)

4.1.2. Select the viewmodel created earlier

4.1.3. Click "Select" to confirm

4.2. Add any widget to the hierarchy (e.g. "Progress Bar")

4.2.1. Select the widget

4.3. Open the "View bindings" tab ("Window – View Bindings")

4.3.1. Click "Add Widget" (plus icon)

4.3.2. On the first listbox, choose a boolean property (e.g. "Is Enabled")

4.3.3. On the third listbox, choose "Conversion Functions" and examine the list. Under the "Math" category, comparison functions like "integer < integer" or "float > float" are missing.

4.3.4. On the first listbox, choose an integer or float property (e.g. "Percentage")

4.3.5. On the third listbox, choose "Conversion Functions" and examine the list. Under the "Math" category, arithmetic functions like "integer + integer" or "float * float" are missing.

Workarounds:

A) Editor Preferences – Blueprint Editor Settings - Enable Type Promotion = disabled

B) Project Settings – UMG Model View Viewmodel – Conversion Function Filter = "Conversion Function Library" (was "Blueprint Action Registry")

C) Manually create typed comparison/arithmetic pure functions as needed on a Blueprint Function Library