Postgis table with float type attribute interprets null as zero.

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Author Name: cgsbob - (cgsbob -)
Original Redmine Issue: 962

Redmine category:vectors
Assignee: Jürgen Fischer

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I tried to use Symbology>Continuous Color on a field that has nulls and noticed that these null values are interpreted as 0. As a result, I am getting a lot of black dots on my map (which I hoped would not show up on my map) along with white to red colored dots.

I also notice that "Open attribute table" shows these fields as 0 instead of null.

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• nullprob.png (cgsbob -)
• nulls_appear.png (cgsbob -)
• zoom_lower_right.png (cgsbob -)
• gw_elev.pgdmp (cgsbob -)

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Author Name: Frank Warmerdam - (Frank Warmerdam -)

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I chatted about this very briefly on IRC and Bob reasonable suggested that the attribute table ought to show the field as NULL (perhaps blank) and the rendering might just not draw features with null fields for classification.

I skimmed the OGR provider and I see it makes no effort to distingish between NULL and non-null fields. Is it intended that providers can return features with NULL attributes marked in some fashion in the attribute map? Perhaps, those attributes should just not be added to the attribute map for that feature?

Skimming the Postgres provider, it also seems to make no effort to distingish between null and non-null field values.

Perhaps the problem is just at the provider level?

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Author Name: cgsbob - (cgsbob -)

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Replying to "cgsbob":/issues/show/962:
The image I just uploaded has a bug :-) The beginning arrow coming from the pgadmin3 window should begin at record 141 (one cell below).

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Author Name: cgsbob - (cgsbob -)

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Replying to [comment:2 cgsbob]:

Replying to "cgsbob":/issues/show/962:
The image I just uploaded has a bug :-) The beginning arrow coming from the pgadmin3 window should begin at record 141 (one cell below).
Disregard this the comment above...it is correct. Is there a way to delete comments?

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Author Name: Jürgen Fischer (@jef-n)

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

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Author Name: cgsbob - (cgsbob -)

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Replying to [comment:5 jef]:
I see that the attribute table now shows nulls as NULL, but the feature is still rendered as black dots. I was hoping that fixing #11021 meant that the null attributes would not be rendered.

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Author Name: Jürgen Fischer (@jef-n)

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• status_id was changed from Closed to Feedback
• resolution was changed from fixed to

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Author Name: Jürgen Fischer (@jef-n)

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fixed in

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• status_id was changed from Feedback to Closed
• resolution was changed from to fixed

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Author Name: cgsbob - (cgsbob -)

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Replying to [comment:8 jef]:

fixed in
I wish this was an easier bug to fix, but there is still a problem :-) The null point features the color range white to red). When you zoom in these null point features disappears.

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Author Name: Jürgen Fischer (@jef-n)

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Replying to [comment:9 cgsbob]:

Replying to [comment:8 jef]:

fixed in
I wish this was an easier bug to fix, but there is still a problem :-) The null point features the color range white to red). When you zoom in these null point features disappears.

Sorry, I don't get what you're saying. Did you post get mixed up?

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• resolution was changed from fixed to
• status_id was changed from Closed to Feedback

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Author Name: cgsbob - (cgsbob -)

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Replying to [comment:10 jef]:

Replying to [comment:9 cgsbob]:

Replying to [comment:8 jef]:

fixed in
I wish this was an easier bug to fix, but there is still a problem :-) The null point features the color range white to red). When you zoom in these null point features disappears.

Sorry, I don't get what you're saying. Did you post get mixed up?
Yes, I did mix up my post. I was trying to say that the features that have null attribute still appear in my map and when I zoom in those features they disappear. I'll upload some pics to demonstrate.

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Author Name: Jürgen Fischer (@jef-n)

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You probably missed the working version. might have worked, but my optimization in 9a584ed (SVN r8287) actually broke the postgres provider. I think I've fixed that in fa696cd (SVN r8291).

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• status_id was changed from Feedback to Closed
• resolution was changed from to fixed

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Author Name: Jürgen Fischer (@jef-n)

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• resolution was changed from fixed to
• status_id was changed from Closed to Feedback

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Author Name: Jürgen Fischer (@jef-n)

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thanks for the patience. I think I finally got it right.

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• status_id was changed from Feedback to Closed
• resolution was changed from to fixed

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Author Name: cgsbob - (cgsbob -)

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Replying to [comment:14 jef]:

thanks for the patience. I think I finally got it right.
I just updated from svn. Everything (well, almost everything :) ) is all right. One little cosmetic change you can make is to update the extent.

Thanks for all your work!

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Author Name: Jürgen Fischer (@jef-n)

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Replying to [comment:15 cgsbob]:

One little cosmetic change you can make is to update the extent.

I don't think the is a rendering issue. If you don't want to handle the null features at all, I'd suggest that you filter them out using a where clause.