Hi all,
I'm on a situation where a Filter needs to be split into backend's
supported/unsupported parts, hence using CapabilitiesFilterSplitter.
The thing is that some attribute name are encodable to the backend's
query language and some other's don't, and need to be evaluated at
runtime.
Now, CapabilitiesFilterSplitter is not designed for extensibility, and
there's currently no way of determining whether a filter that includes
a given PropertyName is supported or not, assuming all of them are
supported.
Now, in order to accomplish my goal with the least disruption
possible, I came to a solution that implies extending the
ClientTransactionAccessor extension point's contract.
ClientTransactionAccessor is used when evaluating a PropertyName
through the following method:
Filter getUpdateFilter(String attributePath);
Which returns either null (for no change, meaning the filter
referencing the property path is supported), or am or'ed filter which
replaces the original filter (currently only used by wfs 1.0 client as
far as I can see).
My proposal is to state that returning Filter.EXCLUDE means that
property name is not supported by the backend, so that
CapabilitiesFilterSplitter adds the referencing filter to the
post-processing filter instead of to the pre-processing filter. This
would be more convenient than opening CapabilitiesFilterSplitter for
extension (making its state
Please take a look at the patch bellow and tell whether it's ok to commit.
diff --git
a/modules/library/main/src/main/java/org/geotools/filter/visitor/CapabilitiesFilterSplitter.java
b/modules/library/main/src/main/java/org/geotools/filter/visitor/CapabilitiesFilterSplitter.java
index 5853789..ec43fb5 100644
---
a/modules/library/main/src/main/java/org/geotools/filter/visitor/CapabilitiesFilterSplitter.java
+++
b/modules/library/main/src/main/java/org/geotools/filter/visitor/CapabilitiesFilterSplitter.java
@@ -801,8 +801,13 @@ public class CapabilitiesFilterSplitter
implements FilterVisitor, ExpressionVisi
Filter updateFilter = (Filter)
transactionAccessor.getUpdateFilter(expression
.getPropertyName());
if (updateFilter != null) {
- changedStack.add(updateFilter);
- preStack.push(updateFilter);
+ if(updateFilter == Filter.EXCLUDE){
+ // property name not encodable to backend
+ postStack.push(expression);
+ }else{
+ changedStack.add(updateFilter);
+ preStack.push(updateFilter);
+ }
} else
preStack.push(expression);
} else {
diff --git
a/modules/library/main/src/main/java/org/geotools/filter/visitor/ClientTransactionAccessor.java
b/modules/library/main/src/main/java/org/geotools/filter/visitor/ClientTransactionAccessor.java
index 11d002c..6b8e01b 100644
---
a/modules/library/main/src/main/java/org/geotools/filter/visitor/ClientTransactionAccessor.java
+++
b/modules/library/main/src/main/java/org/geotools/filter/visitor/ClientTransactionAccessor.java
@@ -43,7 +43,10 @@ public interface ClientTransactionAccessor {
* Returns all the filters of updates that affect the
attribute in the expression ORed together.
*
* @param attributePath the xpath identifier of the attribute.
- * @return all the filters of updates that affect the
attribute in the expression ORed together.
+ * @return all the filters of updates that affect the
attribute in the expression ORed together,
+ * {@link Filter#EXCLUDE} if the attribute path is not
supported/encodable to the backend
+ * (and hence any filter including it shall only be evaluated
at runtime), or {@code null} if no behavior
+ * change is to be applied.
*/
Filter getUpdateFilter(String attributePath);
--
Gabriel Roldan
OpenGeo - http://opengeo.org
Expert service straight from the developers.
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