/*
* Copyright 2013 Robert von Burg <eitch@eitchnet.ch>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package li.strolch.model.query;
import li.strolch.model.Resource;
import li.strolch.model.ResourceVisitor;
import li.strolch.model.parameter.Parameter;
import li.strolch.model.query.ordering.StrolchQueryOrdering;
import li.strolch.model.visitor.NoStrategyResourceVisitor;
import li.strolch.utils.dbc.DBC;
/**
* <p>
* {@link ResourceQuery} is the user API to query {@link Resource Resources} in Strolch. The {@link Navigation} is used
* to navigate to a type of resource on which any further {@link Selection Selections} will be performed. The
* {@link ResourceVisitor} is used to transform the returned object into a domain specific object (if required). This
* mechanism allows you to query only the values of a {@link Parameter} instead of having to return all the elements and
* then performing this transformation.
* </p>
*
* <p>
* The {@link ResourceVisitor} is intended for situations where the query result should not be {@link Resource} but some
* other object type. For instance in a restful API, the result might have to be mapped to a POJO, thus using this
* method can perform the mapping step for you
* </p>
*
* @param <U>
* defines the return type of this query. Depending on the user {@link ResourceVisitor} this query can return
* a {@link Resource}, or any type of object to which the visitor mapped the resource
*
* @author Robert von Burg <eitch@eitchnet.ch>
*/
public class ResourceQuery<U> extends StrolchElementQuery<ResourceQueryVisitor> {
protected ResourceVisitor<U> resourceVisitor;
protected StrolchQueryOrdering ordering;
public ResourceQuery() {
super();
}
public ResourceQuery(Navigation navigation) {
super(navigation);
}
public ResourceVisitor<U> getResourceVisitor() {
return this.resourceVisitor;
}
public ResourceQuery<U> setResourceVisitor(ResourceVisitor<U> resourceVisitor) {
DBC.PRE.assertNotNull("resourceVisitor", resourceVisitor);
this.resourceVisitor = resourceVisitor;
return this;
}
public StrolchQueryOrdering getOrdering() {
return this.ordering;
}
public ResourceQuery<U> setOrdering(StrolchQueryOrdering ordering) {
this.ordering = ordering;
return this;
}
@Override
public ResourceQuery<U> with(Selection selection) {
super.with(selection);
return this;
}
@Override
public ResourceQuery<U> not(Selection selection) {
super.not(selection);
return this;
}
@Override
public ResourceQuery<U> withAny() {
super.withAny();
return this;
}
@Override
public void accept(ResourceQueryVisitor visitor) {
DBC.PRE.assertNotNull("resourceVisitor", this.resourceVisitor);
super.accept(visitor);
if (this.ordering != null)
this.ordering.accept(visitor);
}
public static ResourceQuery<Resource> query(String type) {
return new ResourceQuery<Resource>(new StrolchTypeNavigation(type))
.setResourceVisitor(new NoStrategyResourceVisitor());
}
public static ResourceQuery<Resource> query(String type, StrolchQueryOrdering ordering) {
return new ResourceQuery<Resource>(new StrolchTypeNavigation(type))
.setResourceVisitor(new NoStrategyResourceVisitor()).setOrdering(ordering);
}
public static <U> ResourceQuery<U> query(String type, ResourceVisitor<U> resourceVisitor) {
return new ResourceQuery<U>(new StrolchTypeNavigation(type)).setResourceVisitor(resourceVisitor);
}
public static <U> ResourceQuery<U> query(String type, ResourceVisitor<U> resourceVisitor,
StrolchQueryOrdering ordering) {
return new ResourceQuery<U>(new StrolchTypeNavigation(type)).setResourceVisitor(resourceVisitor)
.setOrdering(ordering);
}
}