I love the new widgets in WAB 2.1!
For layers with domains Filter and Query work perfect, with a dropdown menu for users to select values from an attribute.
However, for layers without domains (most of ours)... they have to know the values and how they are formatted. This will be a stopping point for users. However, the solution would be to let the developer instruct the Filter widget to populate the menu with all values, or with a representative sample of values, or maybe the first 10 values, or first 'x' amount of values. So the user knows the "format" of the data and values, to input into the Contains entry, you know?
However, the real end users, the public, will not know these terms. Or how to format them.
:::::::UPDATE:::::::::: 9/26 --- using Unique Values and setting it to "IS" operator seems to populate the menu with all unique values. This is perfect. For now. I imagine if there were thousands of unique values that might bog down the browser and make the menu long and unwieldy. Therefore some method of selecting 'representative' values or the first "x" values could still be helpful.