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I am having some issues trying to show multiple fields for a single label in QGIS. In QGIS2.6, attempting to display labels for a feature consisting of multiple fields results in an empty label if one of the fields is null. So for example, in the label expression dialog:

concat("Temp Site",'\n',"Notes",'\n',"Function")

will function normally unless one of the fields is null, then it results in no label being shown. Using the '||' operator instead in the expression dialog also results in the same behaviour:

"Temp Site" || '\n'  ||  "Notes" || '\n'  ||  "Function"

Is there a way to display the labels even if one of the fields is null?

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2 Answers 2

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Use the "Coalesce" function. Coalesce takes the first non-null value from its arguments. So this expression should work:

coalesce("Temp Site",'') || '\n'  ||  coalesce("Notes",'') || '\n'  ||  coalesce("Function",'')
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    You can also wrap the new line within the coalesce function, if it makes sense to avoid the blank lines in the middle of the label I used an expression like coalesce("Temp Site", ' ') || coalesce(('\n' || "Notes"), ' ') || coalesce(('\n' || "Function"), ' ' )
    – Brian Fisher
    Jan 22, 2018 at 10:39
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Update: This is no longer a problem. In QGIS 2.10 and greater Concat ignores null values and coalesce is no longer needed. See this answer instead Handling NULL values in labeling?

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