net.yadaframework.web.YadaPageRows Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of yadaweb Show documentation
Some useful tasks for the Yada Framework
The newest version!
package net.yadaframework.web;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;

import net.yadaframework.exceptions.YadaInvalidUsageException;

/**
 * A page of rows fetched using YadaPageRequest
 *
 * @param  the type of each row
 * @see YadaPageRequest
 */
public class YadaPageRows implements Iterable {
	private final List rows = new ArrayList();
	private final YadaPageRequest currentPageRequest;
	private Long outOfRows = null; // Total number of elements that would be returned without pagination
	private boolean hasMoreRows = false;

	/**
	 * This constructor is useful when dynamically adding rows to an existing list on user interaction
	 */
	public YadaPageRows() {
		currentPageRequest = null;
		hasMoreRows = false;
	}

	/**
	 * @param rows the result
	 * @param currentPageRequest the page request that generated this result
	 * @param outOfRows count of the total number of rows that would be returned without pagination
	 */
	public YadaPageRows(List rows, YadaPageRequest currentPageRequest, long outOfRows) {
		this(rows, currentPageRequest);
		this.outOfRows = outOfRows;
		// If we loaded all previous pages too, then rows.size() counts rows from all previous pages
		long totSoFar = currentPageRequest.getFirstResult() + rows.size();
		if (totSoFar > outOfRows) {
			throw new YadaInvalidUsageException("Found more rows that the maximum count: the value of outOfRows is too small");
		}
	}

	/**
	 *
	 * @param rows the result
	 * @param currentPageRequest the page request that generated this result
	 */
	public YadaPageRows(List rows, YadaPageRequest currentPageRequest) {
		this.rows.addAll(rows);
		this.currentPageRequest = currentPageRequest;
		// We have fetched one more row to check if there is more data after the current page, so we have to fix that
		this.hasMoreRows = rows.size()==currentPageRequest.getMaxResults();
		if (this.hasMoreRows) {
			// removing the last element that was fetched just to check for more data
			this.rows.remove(this.rows.size()-1);
		}
	}

	public String getPageParam() {
		String paramPrefix = currentPageRequest.getParamPrefix();
		paramPrefix = paramPrefix==null?"":paramPrefix + ".";
		return paramPrefix + "page";
	}

	public String getSizeParam() {
		String paramPrefix = currentPageRequest.getParamPrefix();
		paramPrefix = paramPrefix==null?"":paramPrefix + ".";
		return paramPrefix + "size";
	}

	public String getLoadPreviousParam() {
		String paramPrefix = currentPageRequest.getParamPrefix();
		paramPrefix = paramPrefix==null?"":paramPrefix + ".";
		return paramPrefix + "loadPrevious";
	}

	/**
	 * Returns the page data fetched from database. It also contains the rows of all previous pages if {@link YadaPageRequest#isLoadPrevious()} is true
	 * @return
	 */
	public List getRows() {
		return rows;
	}

	/**
	 *
	 * @return the number of rows fetched from database, can be less, equal or higher than the page size
	 */
	public int getRowNumber() {
		return rows.size();
	}

	/**
	 *
	 * @return the page size
	 */
	public int getPageSize() {
		return currentPageRequest!=null?currentPageRequest.getSize():0;
	}

	/**
	 *
	 * @return the page number
	 */
	public int getPage() {
		return currentPageRequest!=null?currentPageRequest.getPage():0;
	}

	/**
	 *
	 * @return the next page number. If there are no more rows, this number is invalid.
	 */
	public int getNextPage() {
		return currentPageRequest!=null?currentPageRequest.getNextPageRequest().getPage():0;
	}

	/**
	 *
	 * @return the YadaPageRequest that generated this YadaPageContent
	 */
	public YadaPageRequest getYadaPageRequest() {
		return currentPageRequest;
	}

	/**
	 *
	 * @return the total number of rows (count) that would be returned without pagination
	 */
	public long getOutOfRows() {
		if (outOfRows==null) {
			throw new YadaInvalidUsageException("outOfRows has not been initialized");
		}
		return outOfRows;
	}

	/**
	 *
	 * @return true if there is more data to fetch from the database, false if this is the last available page
	 */
	public boolean hasMoreRows() {
		return hasMoreRows;
	}

	/**
	 * @return true if there are no elements
	 */
	public boolean isEmpty() {
		return rows.isEmpty();
	}

	/**
	 * @return true if this is the first page
	 */
	public boolean isFirst() {
		return currentPageRequest!=null?currentPageRequest.isFirst():true;
	}

	/**
	 * @return true if this is the last page in the database
	 */
	public boolean isLast() {
		return !hasMoreRows;
	}

	@Override
	public Iterator iterator() {
		return rows.iterator();
	}

	@Override
	public int hashCode() {
		return Objects.hash(rows, hasMoreRows, outOfRows, currentPageRequest);
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj) {
			return true;
		}
		if (obj == null) {
			return false;
		}
		if (getClass() != obj.getClass()) {
			return false;
		}
		@SuppressWarnings("unchecked")
		YadaPageRows other = (YadaPageRows) obj;
		return Objects.equals(rows, other.rows) && hasMoreRows == other.hasMoreRows && outOfRows == other.outOfRows
				&& Objects.equals(currentPageRequest, other.currentPageRequest);
	}

	/**
	 * Returns the next page request, for use in the "load more" buttons, or null if this is the last page.
	 * @return
	 */
	public YadaPageRequest getNextPageRequest() {
		if (!hasMoreRows) {
			return null;
		}
		return currentPageRequest.getNextPageRequest();
	}

	/**
	 * This method is useful when dynamically adding rows to an existing list on user interaction
	 */
	public void add(T row) {
		rows.add(row);
	}


}