conditional formatting by field not available for direct query

Hey,

I can't confirm this, make sure you are using the latest Power BI Desktop version, I'm using the May 2019 release (check --> Help --> About).

Here you can see that I'm connected to a data model using direct query:

This directquery data source is a SQL Server 2017 database, but I can also confirm that this also works with other dirctquery datasources. 

Make sure that your measure returns a text string, this string has to be either

• a valid color name (https://www.w3schools.com/colors/colors_names.asp) or 
• a valid hexcode representing one of the unnamed colors (including the # sign

This is how I apply a measure for conditional formatting (here the background):

I choose: Format by "Field value":

I select the measure that returns the text encoded color that I want to apply to the background:

And this is how the table will look like:

And this is how the measure look liks:

vizAid Background Color -  Quantity = 
SWITCH(
    TRUE()
    , v_Quantity < 11000, [vizAid trafficlight bad]
    , AND([Total Quantity] >= 11000, [Total Quantity] < 15000) , [vizAid Color trafficlight maybe]
    , "Darkgrey"
)

This measure is referencing two other measures, these measures just define a color, like so:

vizAid trafficlight bad = "Crimson"

Hopefully this provides some ideas.

Regards,
Tom