SimpleQueryImpl.java

package com.googlecode.objectify.impl;

import com.google.appengine.api.datastore.Cursor;
import com.google.appengine.api.datastore.Entity;
import com.googlecode.objectify.cmd.QueryKeys;
import com.googlecode.objectify.cmd.SimpleQuery;


/**
 * Base for command classes that include methods for defining a query (filter, order, limit, etc).
 * Does not include the methods for executing a query.
 *
 * @author Jeff Schnitzer <jeff@infohazard.org>
 */
public abstract class SimpleQueryImpl<T> implements SimpleQuery<T>
{
	/** */
	protected LoaderImpl<?> loader;

	/**
	 * There is a special case - if loader is null, use 'this' as the LoaderImpl. It's a bit of a hack
	 * but we can't pass in 'this' to super constructors.
	 */
	SimpleQueryImpl(LoaderImpl<?> loader) {
		this.loader = loader == null ? (LoaderImpl<?>)this : loader;
	}

	/**
	 * Create an initial query object; for a typed query this will have a class, otherwise it will be generic.
	 * For the real QueryImpl itself this is a clone() operation.
	 */
	abstract QueryImpl<T> createQuery();

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.QueryCommon#filterKey(java.lang.String, java.lang.Object)
	 */
	@Override
	public QueryImpl<T> filterKey(String condition, Object value) {
		QueryImpl<T> q = createQuery();
		q.addFilter(Entity.KEY_RESERVED_PROPERTY + " " + condition.trim(), value);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.SimpleQuery#filterKey(java.lang.Object)
	 */
	@Override
	public QueryImpl<T> filterKey(Object value) {
		return filterKey("=", value);
	}

	@Override
	public QueryImpl<T> orderKey(boolean descending) {
		String prefix = descending ? "-" : "";

		QueryImpl<T> q = createQuery();
		q.addOrder(prefix + Entity.KEY_RESERVED_PROPERTY);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.Query#ancestor(java.lang.Object)
	 */
	@Override
	public QueryImpl<T> ancestor(Object keyOrEntity) {
		QueryImpl<T> q = createQuery();
		q.setAncestor(keyOrEntity);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.Query#limit(int)
	 */
	@Override
	public QueryImpl<T> limit(int value) {
		QueryImpl<T> q = createQuery();
		q.setLimit(value);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.Query#offset(int)
	 */
	@Override
	public QueryImpl<T> offset(int value) {
		QueryImpl<T> q = createQuery();
		q.setOffset(value);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.Query#startCursor(com.google.appengine.api.datastore.Cursor)
	 */
	@Override
	public QueryImpl<T> startAt(Cursor value) {
		QueryImpl<T> q = createQuery();
		q.setStartCursor(value);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.Query#endCursor(com.google.appengine.api.datastore.Cursor)
	 */
	@Override
	public QueryImpl<T> endAt(Cursor value) {
		QueryImpl<T> q = createQuery();
		q.setEndCursor(value);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.Query#chunk(int)
	 */
	@Override
	public QueryImpl<T> chunk(int value) {
		QueryImpl<T> q = createQuery();
		q.setChunk(value);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.SimpleQuery#hybrid(boolean)
	 */
	@Override
	public QueryImpl<T> hybrid(boolean force) {
		QueryImpl<T> q = createQuery();
		q.setHybrid(force);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.SimpleQuery#chunkAll()
	 */
	@Override
	public QueryImpl<T> chunkAll()
	{
		return chunk(Integer.MAX_VALUE);
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.Query#keys()
	 */
	@Override
	public QueryKeys<T> keys() {
		QueryImpl<T> q = createQuery();
		q.setKeysOnly();
		return new QueryKeysImpl<>(q);
	}
	
	 /* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.SimpleQuery#reverse()
	 */
	@Override
	public QueryImpl<T> reverse() {
		QueryImpl<T> q = createQuery();
		q.toggleReverse();
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.SimpleQuery#distinct(boolean)
	 */
	@Override
	public QueryImpl<T> distinct(boolean value) {
		QueryImpl<T> q = createQuery();
		q.setDistinct(value);
		return q;
	}

	/* (non-Javadoc)
	 * @see com.googlecode.objectify.cmd.SimpleQuery#project(String...)
	 */
	@Override
	public QueryImpl<T> project(String... fields) {
		QueryImpl<T> q = createQuery();
		q.addProjection(fields);
		return q;
	}

}