How can Query All Entries??

[Marcel Schneider]

Hello,

how can reteice all object without a special select-statement, but with and queryseletion, like order by.

thanks alot

[Niall]

Hi Marcel,

Currently with the built-in queries, the only way is to use a query which will evaluate true for every object. Like 'has(Car.CAR_ID)' or something like that.

I am planning to add 'all()' and 'none()' to CQEngine in future, but you can add them to your app now with the following class.

To use it:

ResultSet<Car> allCarsOrderedByPrice = retrieve(all(Car.class), queryOptions(orderBy(descending(Car.PRICE))));

package com.googlecode.cqengine.query;

import com.googlecode.cqengine.attribute.Attribute;
import com.googlecode.cqengine.attribute.SelfAttribute;
import com.googlecode.cqengine.attribute.SimpleAttribute;
import com.googlecode.cqengine.query.simple.SimpleQuery;

/**
 * Adds literal queries all() and none() to CQEngine query syntax.
 * <p/>
 * To use these queries, add a static import for {@code LiteralQueryFactory.*}.
 *
 * @author ngallagher
 */
public class LiteralQueryFactory {

    static class LiteralQuery<O> extends SimpleQuery<O, O> {

        final boolean literalValue;

        public LiteralQuery(Class<O> objectType, boolean literalValue) {
            super(new SelfAttribute<O>(objectType, String.valueOf(literalValue)));
            this.literalValue = literalValue;
        }

        @Override
        protected boolean matchesSimpleAttribute(SimpleAttribute<O, O> attribute, O object) {
            return literalValue;
        }

        @Override
        protected boolean matchesNonSimpleAttribute(Attribute<O, O> attribute, O object) {
            return literalValue;
        }

        @Override
        protected int calcHashCode() {
            return 1413898556; // chosen randomly
        }
    }

    /**
     * Private constructor, not used.
     */
    LiteralQueryFactory() {
    }

    public static <O> Query<O> all(Class<O> objectType) {
        return new LiteralQuery<O>(objectType, true);
    }

    public static <O> Query<O> none(Class<O> objectType) {
        return new LiteralQuery<O>(objectType, false);
    }
}

HTH,
Niall

[Marcel Schneider]

thank you,

i think, i am waiting at least for the all()-subquery, i have used a one-member (true) criteria, it is okay at this time, like this project ;)

ciao

Marcel

[Niall]

This is done, you can find all() in CQEngine 1.3.1 :)