NULL Strings in Mif files don't interact well with expressions (regression)

[qgib]

Author Name: Ian Turton (@ianturton)
Original Redmine Issue: 14487
Affected QGIS version: 2.14.0
Redmine category:expressions

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I have a mif file that is used in training and prior to 2.14 we would select polygons with no name by using

"name" is NOT NULL 

in the expression builder. In 2.14 this now selects all the features including the 23 with empty/null names. You also can't do a work round like

length("name") = 0 

as none of the features match.

Saving the data as a Shapefile makes everything work as expected.

I've attached the mif/mid files.

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• parishes_surrey.mif (Ian Turton)
• parishes_surrey.mid (Ian Turton)

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

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Looking at this - there's no NULL names in the file. There's names which are empty strings, but that's different to null.

length("name") > 0 works for me, it selects 147 features
similarly
"name" <> '' also works (selects same 147 features)

I'm not sure why this would have worked in earlier versions (perhaps it was a change in the underlying GDAL library), but there's no reproducable bug here.

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• resolution was changed from to invalid
• status_id was changed from Open to Closed