Hi,
I am creating a model that fixes Network files before they are used in
the QGIS Network analysis (Shortest path) tools.
This is my work flow:
1. Create a "Length" field (value) and calculate $length in the field
calculator
2. Split the Multipart lines into Singlepart lines
3. Create a "Length*2*" field (value) and calculate $length in the
field calculator
4. Select by expression Length != Length2. This basically gives me a
selection of line that have been modified by the Multipart to
Singlepart algorithm. (I get 8 results)
This works well
The problem is when I create and Input String to let the user create a
"Length" field. This become a variable called @NamelengthField. My work
flow become:
1. User input "Length" in the Model input. (@NamelengthField)
2. Create a "Length" field using @NamelengthField (as pre-calculated
value) and calculate $length in the field calculator: This is OK
3. Split the Multipart lines into Singlepart lines: This is OK
4. Create a "Length2" field using @NamelengthField ||'2' (as
pre-calculated value) and calculate $length in the field calculator:
This is OK this field (Length2) is created and calculated properly.
5. I get stuck when I try Select by expression using @NamelengthField
!= @NamelengthField || '2' (as pre-calculated value) (I get all
lines back) and the test does not work.
I tried stuff like
@NamelengthField != (@NamelengthField || '2')
'@NamelengthField != @NamelengthField || '2''
"@NamelengthField != @NamelengthField || '2'"
"@NamelengthField"|| !=|| "@NamelengthField || '2'"
Even simple @NamelengthField = 5.286365157529550 (which should extract
exactly one value).
Any ideas?
Nicolas
QGIS 3.18.2 on Windows 10
--
Nicolas Cadieux
https://gitlab.com/njacadieux
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