/
FilteringDataProviderWrapper.java
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/
FilteringDataProviderWrapper.java
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/*
* Copyright 2000-2016 Vaadin Ltd.
*
* 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 com.vaadin.server.data;
import java.util.stream.Stream;
import com.vaadin.server.SerializableFunction;
import com.vaadin.shared.Registration;
/**
* Wrapper class for modifying, chaining and replacing filters in a query. Used
* to create a suitable {@link Query} for the underlying data provider with
* correct filters.
*
* @author Vaadin Ltd.
* @since
*
* @param <T>
* data provider data type
* @param <F>
* wrapper query filter type
* @param <M>
* underlying data provider filter type
*/
public abstract class FilteringDataProviderWrapper<T, F, M>
implements DataProvider<T, F> {
/**
* Variant of data provider wrapper that supports chaining filters.
*
* @param <T>
* the data provider data type
* @param <F>
* the data provider filter type
*/
protected abstract static class AppendableFilterDataProviderWrapper<T, F>
extends FilteringDataProviderWrapper<T, F, F>
implements AppendableFilterDataProvider<T, F> {
/**
* Constructs a filtering wrapper for a data provider with filter
* chaining.
*
* @param dataProvider
* the wrapped data provider
*/
protected AppendableFilterDataProviderWrapper(
AppendableFilterDataProvider<T, F> dataProvider) {
super(dataProvider);
}
@Override
public F combineFilters(F filter1, F filter2) {
return ((AppendableFilterDataProvider<T, F>) dataProvider)
.combineFilters(filter1, filter2);
}
}
/**
* The actual data provider behind this wrapper.
*/
protected DataProvider<T, M> dataProvider;
/**
* Constructs a filtering wrapper for a data provider.
*
* @param dataProvider
* the wrapped data provider
*/
protected FilteringDataProviderWrapper(DataProvider<T, M> dataProvider) {
this.dataProvider = dataProvider;
}
@Override
public boolean isInMemory() {
return dataProvider.isInMemory();
}
@Override
public void refreshAll() {
dataProvider.refreshAll();
}
@Override
public Registration addDataProviderListener(DataProviderListener listener) {
return dataProvider.addDataProviderListener(listener);
}
@Override
public int size(Query<T, F> t) {
return dataProvider.size(new Query<>(t.getOffset(), t.getLimit(),
t.getSortOrders(), t.getInMemorySorting(), getFilter(t)));
}
@Override
public Stream<T> fetch(Query<T, F> t) {
return dataProvider.fetch(new Query<>(t.getOffset(), t.getLimit(),
t.getSortOrders(), t.getInMemorySorting(), getFilter(t)));
}
/**
* Gets the filter that should be used in the modified Query.
*
* @param query
* the current query
* @return filter for the modified Query
*/
protected abstract M getFilter(Query<T, F> query);
/**
* Creates a data provider wrapper with a static filter set to each Query.
* This {@code DataProvider} will deliberately ignore any possible filters
* from the Query.
*
* @see DataProvider#setFilter(Object)
*
* @param dataProvider
* the underlying data provider
* @param filter
* the static filter for each query
*
* @param <T>
* data provider data type
* @param <F>
* query filter type
*
* @return wrapped data provider with static filter
*/
public static <T, F> DataProvider<T, Void> filter(
DataProvider<T, F> dataProvider, F filter) {
return new FilteringDataProviderWrapper<T, Void, F>(dataProvider) {
@Override
protected F getFilter(Query<T, Void> query) {
return filter;
}
};
}
/**
* Creates a data provider wrapper with filter type mapping. The mapper
* function will be applied to a query filter if it is present.
*
* @see DataProvider#convertFilter(SerializableFunction)
*
* @param dataProvider
* the underlying data provider
* @param mapper
* the function to map from one filter type to another
*
* @param <T>
* data provider data type
* @param <F>
* wrapper query filter type
* @param <M>
* underlying data provider filter type
*
* @return wrapped data provider with filter conversion
*/
public static <T, F, M> DataProvider<T, F> convert(
DataProvider<T, M> dataProvider,
SerializableFunction<F, M> mapper) {
return new FilteringDataProviderWrapper<T, F, M>(dataProvider) {
@Override
protected M getFilter(Query<T, F> query) {
return query.getFilter().map(mapper).orElse(null);
}
};
}
/**
* Creates a data provider wrapper with a chained filter. The filter will be
* combined to existing filters using
* {@link AppendableFilterDataProvider#combineFilters(Object, java.util.Optional)}.
*
* @param dataProvider
* the underlying data provider
* @param filter
* the chained filter
*
* @param <T>
* data provider data type
* @param <F>
* query filter type
* @return wrapped data provider with chained filter
*/
public static <T, F> AppendableFilterDataProvider<T, F> chain(
AppendableFilterDataProvider<T, F> dataProvider, F filter) {
return new AppendableFilterDataProviderWrapper<T, F>(dataProvider) {
@Override
protected F getFilter(Query<T, F> query) {
return combineFilters(filter, query.getFilter());
}
};
}
}