Recognize columns with default values, treat them accordingly
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Key: GEOT-2526
URL: http://jira.codehaus.org/browse/GEOT-2526
Project: GeoTools
Issue Type: Improvement
Components: data jdbc-ng
Affects Versions: 2.5.5
Reporter: Andrea Aime
Assignee: Andrea Aime
Fix For: 2.6-M2
At the moment columns with a default value receive no special treatment. There
are two things we could do:
a) don't mark the column as non nullable if the schema says "not null" if the
column has a default value
b) don't force a null value during feature insertion if the attribute value has
not been specified, as the default value will be provided by the database
In order to recognize a column with a default value we can use the COLUMN_DEF
metadata, see DatabaseMetadata.getColumns() javadoc:
http://java.sun.com/j2se/1.4.2/docs/api/java/sql/DatabaseMetaData.html
Behaviour a) seems easy enough to get, we just check COLUMN_DEF is not null, in
that case, we ignore the information provided by NULLABLE.
b) is tricky in a few ways. Afaik we have no way to tell if an attribute is not
set, or set with a null value. That is, how do we tell apart a user asking for
an explicit null from one that simply did not set the attribute?
If we have no way, would it be ok to just assume that null attribute + default
value -> use the default value?
The other issue is, if we avoid setting null for null attributes with a default
value, should we issue an extra query in the db to retrieve the generated
default value, or not? And, can we even do this? I guess in the case of a
writer the feature is owned by the writer itself and it's updatable, in the
case of FeatureStore.addFeatures we _could_ update the features passed in
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