Extracting part of string from field in QGIS Field Calculator?

Question

I want to create a new field in my attribute table. My goal: returning all digits between the / and _ characters of the field named "location" by applying the next expression:

regexp_substr( "Text", '/(\\d*)\_' )

based on this working example: Obtaining specific part of string from field in QGIS attribute table?

However, the expression does not give the desired result in my case:

Does anyone know any way to modify/accommodate the expression?

Answer 1

Since the number of characters is the same, you can use the substr() function on a new field as in the following expression:

substr( "Location" ,17,6)

In the above example, I used Path instead of Location

Answer 2

A couple of issues - first, you don't need to escape (i.e. put a backslash before) the underscore. Your pattern also suggests that the digits follow immediately after a forward slash - which they do not, there is a w between them in each of your examples. If this is consistently a w, you could do:

regexp_substr( "location", '/w(\\d*)_' )

but in reality, if you're just trying to get every number before the underscore, you'd be sufficient with:

regexp_substr( "location", '(\\d*)_' )

As can be seen here:

Answer 3

substr("location",16,(length("location")-1))

or

substr(substr("location",17,14),1,6)

that will return "W48535"