Hi, > I don't recall that OpenJUMP can handle having a feature with no > geometry. If nothing else, I think it would choke the renderer and > would throw a null pointer exception. I could be wrong. Maybe one of > the other programmers can comment. > I think the same thing > I suppose it would be possible to make the renderer ignore features > with empty geometries. But there might be other places in the code > where empty geometries would throw exceptions. Like when you select a > row in an attribute table and then flash the feature on the screen or > select it. > Itoo > I do think it is a better idea to return nulls than zeros in most > cases. Is the regular Java null suitable for most cases when OpenJUMP > is connecting to a database? Would it be better to train OpenJUMP to > work with a JDBC null object or a custom object representing a null > value from a Database? > I think java null is a good approximation of what a SQL NULL is.
Michaël > The Sunburned Surveyor > Landon > > On Thu, Jan 28, 2010 at 12:51 AM, Rahkonen Jukka > <jukka.rahko...@mmmtike.fi> wrote: > >> Hi, >> >> It would be a correct behaviour to get nulls instead of zeros, I hope you >> can fix it. But check what happens if some attribute in a table or in the >> result set of a query contains only NULLs. The attribute field should still >> appear to OpenJUMP layer schema, and it should be of a correct data type. >> >> More fundamental question is what to do if geometry field is NULL. It is not >> so uncommon situation with databases, and the aim of many GIS projects is >> just to add spatial data for existing objects with already known attribute >> data by locating them on map. >> >> At present if the result of a PostGIS query contains only NULL geometries >> OpenJUMP throws a Null Pointer Exception. If there are both real geometries >> and NULL geometries in the result se, the lines which are missing geometry >> are skipped. >> >> A DB Query Plugin by Larry Reeder is using a workaroud that has been very >> usable for me: if geometry is missing the plugin creates a default geometry >> as a little rectangle polygon at the origo. By that way user gets the schema >> and attributes to OpenJUMP even if the geometry is empty. What is missing is >> a clever tool for digitizing the real geometry and inserting it in place of >> the default geometry. >> >> So what do developers think about what to do with features which do not have >> geometry? I am remembering that JUMP itself does not necessarily need >> geometry and I am rather sure that I have even seen such things in OpenJUMP. >> I quess I got them to OpenJUMP through opening some shapefile. >> >> -Jukka Rahkonen- >> >> >> >> Michaël Michaud wrote: >> >> >>> Hi, >>> >>> I've got a question for database experts. >>> In DatabaseQueryPlugIn, the following JDBC methods are used to get >>> numeric attributes from database features >>> - ResultSet.getInt() >>> - ResultSet.getDouble() >>> those methods return an int and a double, even if the >>> database contains >>> NULL >>> NULL : getInt() --> 0 >>> NULL : getDouble() --> 0.0 >>> I think that OpenJUMP should get a null value each time the database >>> contains a NULL value. >>> >>> If this there is no special reason to use those methods, I'll >>> change the >>> code to get null instead of 0 in this special cases. >>> >>> Thanks for any suggestion >>> >>> Michaël >>> >>> NB : I noticed another problem with null handling in >>> SimpleQueryPlugIn. >>> I fixed it in the svn that way : >>> select features from layer1 where name = (empty combo box) >>> now returns >>> empty strings AND nulls (empty strings and null are very similar from >>> the end-user point of view) >>> I added "is null" as a function to be able to differentiate null from >>> empty string cases >>> There maybe some corner cases which are still not perfectly handled >>> (when there are null in the dataset and the operator is not >>> "equal" for >>> example) >>> >>> -------------------------------------------------------------- >>> ---------------- >>> The Planet: dedicated and managed hosting, cloud storage, colocation >>> Stay online with enterprise data centers and the best network >>> in the business >>> Choose flexible plans and management services without >>> long-term contracts >>> Personal 24x7 support from experience hosting pros just a >>> phone call away. >>> http://p.sf.net/sfu/theplanet-com >>> _______________________________________________ >>> Jump-pilot-devel mailing list >>> Jump-pilot-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >>> >>> >> ------------------------------------------------------------------------------ >> The Planet: dedicated and managed hosting, cloud storage, colocation >> Stay online with enterprise data centers and the best network in the business >> Choose flexible plans and management services without long-term contracts >> Personal 24x7 support from experience hosting pros just a phone call away. >> http://p.sf.net/sfu/theplanet-com >> _______________________________________________ >> Jump-pilot-devel mailing list >> Jump-pilot-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >> >> > > ------------------------------------------------------------------------------ > The Planet: dedicated and managed hosting, cloud storage, colocation > Stay online with enterprise data centers and the best network in the business > Choose flexible plans and management services without long-term contracts > Personal 24x7 support from experience hosting pros just a phone call away. > http://p.sf.net/sfu/theplanet-com > _______________________________________________ > Jump-pilot-devel mailing list > Jump-pilot-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel > > > ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
