In QGIS, in a Map's item properties, inside print composer, there is an option to "lock layers" (display layers) based on an expression, by using QGIS "expression string builder".

I can use as expression the name of a layer in my QGIS project, and that layer will display in the map in the print composer. I'm sure I am missing some basic operator, but how can I display more than one layer? Which function or operator do I need to use?

1 Answer 1


The answer lies in the documentation.

The expression must be similar to this:

concat ('layer 1', '|', 'layer 2')

In QGIS 3.2, you will now see the expected format for any expression. Read more in the changelog.

  • Thank you. Missed that... and have actually tried the concatenation bar, but without the quotes and the concat function.
    – BMM
    Commented Jun 28, 2018 at 22:59

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