Show some more diverse format for an interval

rduivenvoorde · nyalldawson · commit 51b650afdf64 · 2020-10-05T12:22:22.000+10:00
Before showing an interval of two hours would show you:
interval: 0.0833333 days
Now depending on the range of the interval you will see output
in days, minutes or seconds:

make_interval(years:=0.75)
&lt;interval: 273.938 days&gt;

make_interval(days:=2, hours:=3)
&lt;interval: 2.125 days&gt;

make_interval(hours:=3,days:=1)
&lt;interval: 1.125 days&gt;

make_interval(minutes:=30)
&lt;interval: 30 minutes&gt;

make_interval(minutes:=0.5,seconds:=5)
&lt;interval: 35 seconds&gt;
diff --git a/src/core/expression/qgsexpression.cpp b/src/core/expression/qgsexpression.cpp
@@ -975,7 +975,22 @@ QString QgsExpression::formatPreviewString( const QVariant &value, const bool ht
   else if ( value.canConvert< QgsInterval >() )
   {
     QgsInterval interval = value.value<QgsInterval>();
-    return startToken + tr( "interval: %1 days" ).arg( interval.days() ) + endToken;
+    if ( interval.days() > 1 )
+    {
+      return startToken + tr( "interval: %1 days" ).arg( interval.days() ) + endToken;
+    }
+    else if ( interval.hours() > 1 )
+    {
+      return startToken + tr( "interval: %1 hours" ).arg( interval.hours() ) + endToken;
+    }
+    else if ( interval.minutes() > 1 )
+    {
+      return startToken + tr( "interval: %1 minutes" ).arg( interval.minutes() ) + endToken;
+    }
+    else
+    {
+      return startToken + tr( "interval: %1 seconds" ).arg( interval.seconds() ) + endToken;
+    }
   }
   else if ( value.canConvert< QgsGradientColorRamp >() )
   {
