com.sap.cds.impl.LazyRowImpl Maven / Gradle / Ivy

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/************************************************************************
 * © 2019-2022 SAP SE or an SAP affiliate company. All rights reserved. *
 ************************************************************************/
package com.sap.cds.impl;

import java.util.List;
import java.util.Map;
import java.util.function.Supplier;

import com.google.common.collect.ForwardingMap;
import com.google.common.collect.Maps;
import com.sap.cds.CdsData;
import com.sap.cds.CdsDataStore;
import com.sap.cds.NonUniqueResultException;
import com.sap.cds.Row;
import com.sap.cds.ql.StructuredType;
import com.sap.cds.ql.cqn.CqnSelect;

public class LazyRowImpl extends ForwardingMap implements Row, Lazy {

	private final Supplier rowSupplier;
	private boolean loaded;
	private Row row;

	public LazyRowImpl(Supplier rowSupplier) {
		this.rowSupplier = rowSupplier;
	}

	public static LazyRowImpl lazyRow(CdsDataStore dataStore, CqnSelect query) {
		return new LazyRowImpl(() -> {
			List result = dataStore.execute(query).list();
			if (result.size() == 1) {
				return result.get(0);
			}
			if (result.size() > 1) {
				throw new NonUniqueResultException("Query for single-valued association returned multiple rows");
			}
			return null;
		});
	}

	private Row data() {
		if (!loaded) {
			load();
		}
		return row;
	}

	@Override
	public String toJson() {
		return row != null ? row.toJson() : null;
	}

	@Override
	public String toString() {
		return toJson();
	}

	@Override
	protected Map delegate() {
		return data();
	}

	@Override
	public  T as(Class type) {
		return data().as(type);
	}

	@Override
	public void load() {
		row = rowSupplier.get();
		loaded = true;
	}

	@Override
	public boolean isLoaded() {
		return loaded;
	}

	@Override
	public Object loadData() {
		Row data = data();

		return (data != null) ? Maps.newHashMap(data) : null;
	}

	@Override
	public StructuredType ref() {
		return data().ref();
	}

	@Override
	public  T getPath(String path) {
		return data().getPath(path);
	}

	@Override
	public  T getPathOrDefault(String path, T defaultValue) {
		return data().getPathOrDefault(path, defaultValue);
	}

	@Override
	public  T putPath(String path, T value) {
		return data().putPath(path, value);
	}

	@Override
	public  T putPathIfAbsent(String path, T value) {
		return data().putPathIfAbsent(path, value);
	}

	@Override
	public boolean containsPath(String path) {
		return data().containsPath(path);
	}

	@Override
	public  T removePath(String path) {
		return data().removePath(path);
	}

	@Override
	public  T getMetadata(String key) {
		return data().getMetadata(key);
	}

	@Override
	public  T putMetadata(String key, T value) {
		return data().putMetadata(key, value);
	}

	@Override
	public boolean isForRemoval() {
		return false;
	}

	@Override
	public CdsData forRemoval(boolean remove) {
		throw new UnsupportedOperationException();
	}

}