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I'm facing a big challenge. I need to fill out new fields using "Field Calculator" in QGIS. What do I need to load in those fields?: URL's containing the path to a image file (we can use the statement 'base_file_name'). The thing gets complicated when I'm talking about thousands of records (so I cannot copy and paste every single path into the field, I need to make it automatically during a Graphic Modeler processing).

The drop that spilled the glass is that I need that the fields should be filled out with a matching using an existing field in the Shapefile containing a string with a long text (example: "bf5ae62b-a7c9-4682-9c20-4c457de38a9b") and using this code to match it with a file within a folder (each image file name contains this code, for example: bf5ae62b-a7c9-4682-9c20-4c457de38a9b.jpg). I need to find an expression to make it possible and load all the URL at once using this criteria. Thanks in advance if you can help me.

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Not 100% sure I understand the question, but here's a description of what I do in what seems to be an analogous situation.

I have a layer, Photos, which has a "SourceFile" field that has the fully qualified filename of jpegs. I periodically update it with another layer, NewObservations which has a field, "Identifier". Entries from NewObservations get pasted into Photos and then using field calculator I update the "SourceFile" field to:

concat(@photo_directory,"Identifier",'.jpg')

In this case, @photo_directory is a layer-level variable with the directory of the photos, with trailing \ (Windows). I use a variable for portability.

By the way, I've done this both with "SourceFile" as an actual stored field, and as a virtual field defined in QGIS.

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  • That sounds interesting, I'll try to solve my problem using your method, let's see if this can work. I really appreciate it. – Geografisica Jun 2 '20 at 20:38
  • Thank you, your solution worked perfectly. – Geografisica Jun 8 '20 at 14:24

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