Opened 16 years ago
Closed 15 years ago
#1290 closed patch (fixed)
Shapefile attribute tables do not show lines with null geometry
Reported by: | gabrimonfa | Owned by: | mhugent |
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Priority: | minor: annoyance | Milestone: | Version 1.2.0 |
Component: | Data Provider | Version: | Trunk |
Keywords: | shapefile, null geometry | Cc: | pcav |
Must Fix for Release: | No | Platform: | All |
Platform Version: | Awaiting user input: | no |
Description
I've seen Changeset 2020. Qgis do not crash anymore viewing shapefiles with records with null geometry. But... this records are not shown. Since null geometries are allowed by shapefile format and these records may carry useful data, they should be shown.
Attachments (3)
Change History (15)
comment:1 by , 15 years ago
by , 15 years ago
Attachment: | example.tar.gz added |
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It contains a shapefile with 3 null-geometries. dbf has two fields, one char(16) and one number(16)
comment:2 by , 15 years ago
I've attached a shapefile with 3 empty geometries. The attribute table is like that
Value | Number aa | 1 bb | 2 cc | 0
I'm using qgis 1.2.0-Unstable Trunk at revision 11034. The behavior is different from my first submission. Now the three rows are shown in the attribute table, but instead of the values they show the string "ERROR":
Value | Number ERROR | ERROR ERROR | ERROR ERROR | ERROR
I don't know if the shapefile is exactly coherent with the shapefile format, I've created it with ArcView GIS 3.2a
comment:3 by , 15 years ago
Confirmed. However, I do not see a real use case for what is essentially a non-spatial table: can you help us understanding? Thanks
by , 15 years ago
Attachment: | example2.tar.gz added |
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It contains a shapefile with 3 null-geometries and 1 non-null geometry. dbf has two fields, one char(16) and one number(16)
comment:4 by , 15 years ago
The non-null geom is visualized, and the record shown, the others not. Do you know of other software behaving differently?
comment:5 by , 15 years ago
Hi,
I had the chance to try both the shapes you posted also on arcview 3.x and arcgis 9.x
On arcview 3.x they load fine and attribute tables show the records correctly. Arcgis 9.x works differently: in the first case it gives first a "general function failure" and then, when you open the table, a "error getting a list of OIDs from the table" and shows nothing. In the second case Arcgis 3.x gives directly a "error loading feature class" and do not load the shape.
On the other hand gvSIG seems to open correctly the table.
In what situations do you use such shapefiles? Maybe do you digitize at a later time a vector and then attach it to the table?
comment:6 by , 15 years ago
Sometimes it happens to receive shapefiles with null features, but valid scalar data. Sometimes the geometry is null by mistake and this, for example, may cause errors manipulating such features (i.e. importing or visualizing them).
So it would be useful to be able to inspect this features with qgis and see if the problem is caused by incorrect scalar data in the dbf or something else (corrupted uploaded file for example).
IMHO it is not an oddities to have a null geometry, it is not a "non-geometric" data. AFAIK it is explicitly allowed by shapefile format to have null-geometries. A null geometry is a perfectly legal geometry. Why this should prevent to inspect scalar data?
I think that the fact that dbf values related to null geometries are not shown is yet a bug, even if a minor one.
comment:7 by , 15 years ago
Priority: | major: does not work as expected → minor: annoyance |
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comment:8 by , 15 years ago
Component: | OGR Layer support → Data Provider |
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by , 15 years ago
Attachment: | display_attributes_of_a_null_geometry.patch added |
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crude patch to solve the problem
comment:9 by , 15 years ago
I've added a crude patch to try to solve the problem. (Is this the correct way to provide a possible patch?)
The idea is simple, to fetch only the attributes of the null-geometry row and to mark the feature as not valid to prevent problem with rasterization.
Obviously I don't know if setting mFetchFeaturesWithoutGeom( TRUE ) in qgsvectordataprovider.cpp is a good idea, maybe better solutions are possible that affects only the ogr provider.
The patch works with my test shapefiles.
comment:10 by , 15 years ago
Cc: | added |
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Milestone: | Version 1.0.3 → Version 1.2.0 |
Owner: | changed from | to
Type: | bug → patch |
Thanks!
I changed the owner of the ticket, so Marco will have a look to your patch when he'll be back.
comment:11 by , 15 years ago
Platform: | Unix → All |
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The patch works.
The second part of the patch seems to have been already implemented somehow. It remains to apply the first part "mFetchFeaturesWithoutGeom( TRUE )", if obviously the developers think it is a good idea.
comment:12 by , 15 years ago
Resolution: | → fixed |
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Status: | new → closed |
Applied in r11257 with modifications (kept QgsOGRProvider::featureAtId consistent with QgsOGRProvider::nextFeature). Thanks for the contribution!
Hi,
can you please attach here a shapefile so we can do further tests? Thanks!