Display attribute value from a given layer in QGIS

Question

I am trying to display attribute values from various layers in a QGIS layout using a dynamic text expression. I've been able to calculate statistics for such layers (by following this tutorial: https://www.youtube.com/watch?v=NmdMnfwP3EQ); however, I want to display string attributes and not just statistics.

Is there an expression that allows me to display an attribute of choice from a layer of choice as dynamic text in a QGIS layout? The aim is to present snippets of information from various layers as text labels on the same sheet.

Answer 1

You can use a combination of the attribute and the get_feature (or get_feature_by_id) functions.

attribute takes 2 arguments: a feature and the field from which you want the value. It returns the attribute value of a feature.
get_feature takes 3 arguments: the layer name, the field name, and the field value you wish to match. It returns a feature.

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get_feature_by_id takes 2 arguments: the layer name and the feature id number

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attribute(
    get_feature(
         'mylayer', 
         'myfieldname', 
         'myfieldvalue'),     -- match a feature using the field name and a specific value
    'mytargetfield'           -- get a specific attribute of the matched feature
)

For example, here I find the feature in mylayer that has a value of 1703 in the field myfieldname. The attribute of interest (mytargetfield) has the value B.