How to use

getItems

method

in

org.apache.metamodel.query.FromClause

/**
 * Retrieves a table by it's reference which may be it's alias or it's
 * qualified table name. Typically, this method is used to resolve a
 * SelectItem with a reference like "foo.bar", where "foo" may either be an
 * alias or a table name
 * 
 * @param reference
 * @return a FromItem which matches the provided reference string
 */
public FromItem getItemByReference(String reference) {
  if (reference == null) {
    return null;
  }
  for (final FromItem item : getItems()) {
    FromItem result = getItemByReference(item, reference);
    if (result != null) {
      return result;
    }
  }
  return null;
}

protected String rewriteFromClause(Query query, FromClause fromClause) {
  StringBuilder sb = new StringBuilder();
  if (fromClause.getItemCount() > 0) {
    sb.append(AbstractQueryClause.PREFIX_FROM);
    List<FromItem> items = fromClause.getItems();
    for (int i = 0; i < items.size(); i++) {
      FromItem item = items.get(i);
      if (i != 0) {
        sb.append(AbstractQueryClause.DELIM_COMMA);
      }
      sb.append(rewriteFromItem(query, item));
    }
  }
  return sb.toString();
}

/**
 * Gets the alias of a table, if it is registered (and visible, ie. not part
 * of a sub-query) in the FromClause
 * 
 * @param table
 *            the table to get the alias for
 * @return the alias or null if none is found
 */
public String getAlias(Table table) {
  if (table != null) {
    for (FromItem item : getItems()) {
      String alias = item.getAlias(table);
      if (alias != null) {
        return alias;
      }
    }
  }
  return null;
}

/**
 * Gets the alias of a table, if it is registered (and visible, ie. not part
 * of a sub-query) in the FromClause
 * 
 * @param table
 *            the table to get the alias for
 * @return the alias or null if none is found
 */
public String getAlias(Table table) {
  if (table != null) {
    for (FromItem item : getItems()) {
      String alias = item.getAlias(table);
      if (alias != null) {
        return alias;
      }
    }
  }
  return null;
}

protected String rewriteFromClause(Query query, FromClause fromClause) {
  StringBuilder sb = new StringBuilder();
  if (fromClause.getItemCount() > 0) {
    sb.append(AbstractQueryClause.PREFIX_FROM);
    List<FromItem> items = fromClause.getItems();
    for (int i = 0; i < items.size(); i++) {
      FromItem item = items.get(i);
      if (i != 0) {
        sb.append(AbstractQueryClause.DELIM_COMMA);
      }
      sb.append(rewriteFromItem(query, item));
    }
  }
  return sb.toString();
}

/**
 * Retrieves a table by it's reference which may be it's alias or it's
 * qualified table name. Typically, this method is used to resolve a
 * SelectItem with a reference like "foo.bar", where "foo" may either be an
 * alias or a table name
 * 
 * @param reference
 * @return a FromItem which matches the provided reference string
 */
public FromItem getItemByReference(String reference) {
  if (reference == null) {
    return null;
  }
  for (final FromItem item : getItems()) {
    FromItem result = getItemByReference(item, reference);
    if (result != null) {
      return result;
    }
  }
  return null;
}

/**
 * Examines a query and extracts an array of FromItem's that refer (directly) to tables (hence Joined FromItems and
 * SubQuery FromItems are traversed but not included).
 * 
 * @param q the query to examine
 * @return an array of FromItem's that refer directly to tables
 */
public static FromItem[] getTableFromItems(Query q) {
  List<FromItem> result = new ArrayList<FromItem>();
  List<FromItem> items = q.getFromClause().getItems();
  for (FromItem item : items) {
    result.addAll(getTableFromItems(item));
  }
  return result.toArray(new FromItem[result.size()]);
}

/**
 * Examines a query and extracts an array of FromItem's that refer (directly) to tables (hence Joined FromItems and
 * SubQuery FromItems are traversed but not included).
 * 
 * @param q the query to examine
 * @return an array of FromItem's that refer directly to tables
 */
public static FromItem[] getTableFromItems(Query q) {
  List<FromItem> result = new ArrayList<FromItem>();
  List<FromItem> items = q.getFromClause().getItems();
  for (FromItem item : items) {
    result.addAll(getTableFromItems(item));
  }
  return result.toArray(new FromItem[result.size()]);
}

/**
 * Select all available select items from all currently available FROM
 * items. Equivalent of the expression "SELECT * FROM ..." in SQL.
 * 
 * @return
 */
public Query selectAll() {
  List<FromItem> items = getFromClause().getItems();
  for (FromItem fromItem : items) {
    selectAll(fromItem);
  }
  return this;
}

private Integer getSubQueryFromItemIndex() {
  List<FromItem> fromItems = _query.getFromClause().getItems();
  for (int i = 0; i < fromItems.size(); i++) {
    Query subQuery = fromItems.get(i).getSubQuery();
    if (subQuery != null) {
      if (isSplittable(subQuery)) {
        return i;
      }
    }
  }
  return null;
}

private Integer getSubQueryFromItemIndex() {
  List<FromItem> fromItems = _query.getFromClause().getItems();
  for (int i = 0; i < fromItems.size(); i++) {
    Query subQuery = fromItems.get(i).getSubQuery();
    if (subQuery != null) {
      if (isSplittable(subQuery)) {
        return i;
      }
    }
  }
  return null;
}

/**
 * Select all available select items from all currently available FROM
 * items. Equivalent of the expression "SELECT * FROM ..." in SQL.
 * 
 * @return
 */
public Query selectAll() {
  List<FromItem> items = getFromClause().getItems();
  for (FromItem fromItem : items) {
    selectAll(fromItem);
  }
  return this;
}

private void buildParameterListInFromClause(List<QueryParameter> parameters, Query query) {
  List<FromItem> fromItems = query.getFromClause().getItems();
  for (FromItem fromItem : fromItems) {
    Query subQuery = fromItem.getSubQuery();
    if (subQuery != null) {
      buildParameterListInFromClause(parameters, subQuery);
      buildParameterListInWhereClause(parameters, subQuery);
    }
  }
}

private void buildParameterListInFromClause(List<QueryParameter> parameters, Query query) {
  List<FromItem> fromItems = query.getFromClause().getItems();
  for (FromItem fromItem : fromItems) {
    Query subQuery = fromItem.getSubQuery();
    if (subQuery != null) {
      buildParameterListInFromClause(parameters, subQuery);
      buildParameterListInWhereClause(parameters, subQuery);
    }
  }
}

private Column findColumnInAliasedTable(Column column, FromItem fromItem, String aliasPart, String columnPart) {
  if (column != null) {
    // ensure that if the column has already been found, return it
    return column;
  }
  Table table = fromItem.getTable();
  if (table != null) {
    String alias = fromItem.getAlias();
    if (alias != null && alias.equals(aliasPart)) {
      column = table.getColumnByName(columnPart);
    }
  } else {
    FromItem leftSide = fromItem.getLeftSide();
    column = findColumnInAliasedTable(column, leftSide, aliasPart, columnPart);
    FromItem rightSide = fromItem.getRightSide();
    column = findColumnInAliasedTable(column, rightSide, aliasPart, columnPart);
    if (column != null) {
      Query subQuery = fromItem.getSubQuery();
      if (subQuery != null) {
        List<FromItem> items = subQuery.getFromClause().getItems();
        for (FromItem subQueryFromItem : items) {
          column = findColumnInAliasedTable(column, subQueryFromItem, aliasPart, columnPart);
        }
      }
    }
  }
  return column;
}

private void replaceParametersInFromClause(Object[] values, AtomicInteger parameterIndex, Query originalQuery,
    Query newQuery) {
  final List<FromItem> fromItems = originalQuery.getFromClause().getItems();
  int i = 0;
  for (FromItem fromItem : fromItems) {
    final Query subQuery = fromItem.getSubQuery();
    if (subQuery != null) {
      final Query newSubQuery = newQuery.getFromClause().getItem(i).getSubQuery();
      replaceParametersInQuery(values, parameterIndex, subQuery, newSubQuery);
      newQuery.getFromClause().removeItem(i);
      newQuery.getFromClause().addItem(i, new FromItem(newSubQuery).setAlias(fromItem.getAlias()));
    }
    i++;
  }
}

private void replaceParametersInFromClause(Object[] values, AtomicInteger parameterIndex, Query originalQuery,
    Query newQuery) {
  final List<FromItem> fromItems = originalQuery.getFromClause().getItems();
  int i = 0;
  for (FromItem fromItem : fromItems) {
    final Query subQuery = fromItem.getSubQuery();
    if (subQuery != null) {
      final Query newSubQuery = newQuery.getFromClause().getItem(i).getSubQuery();
      replaceParametersInQuery(values, parameterIndex, subQuery, newSubQuery);
      newQuery.getFromClause().removeItem(i);
      newQuery.getFromClause().addItem(i, new FromItem(newSubQuery).setAlias(fromItem.getAlias()));
    }
    i++;
  }
}

@Override
protected Query beforeRewrite(Query query) {
  query = query.clone();
  JdbcDataContext dataContext = getDataContext();
  if (dataContext != null) {
    String identifierQuoteString = dataContext.getIdentifierQuoteString();
    if (identifierQuoteString != null) {
      List<SelectItem> selectItems = query.getSelectClause().getItems();
      for (SelectItem item : selectItems) {
        String alias = item.getAlias();
        if (needsQuoting(alias, identifierQuoteString)) {
          item.setAlias(identifierQuoteString + alias + identifierQuoteString);
        }
      }
      List<FromItem> fromItems = query.getFromClause().getItems();
      for (FromItem item : fromItems) {
        String alias = item.getAlias();
        if (needsQuoting(alias, identifierQuoteString)) {
          item.setAlias(identifierQuoteString + alias + identifierQuoteString);
        }
      }
    }
  }
  return query;
}

@Override
protected Query beforeRewrite(Query query) {
  query = query.clone();
  JdbcDataContext dataContext = getDataContext();
  if (dataContext != null) {
    String identifierQuoteString = dataContext.getIdentifierQuoteString();
    if (identifierQuoteString != null) {
      List<SelectItem> selectItems = query.getSelectClause().getItems();
      for (SelectItem item : selectItems) {
        String alias = item.getAlias();
        if (needsQuoting(alias, identifierQuoteString)) {
          item.setAlias(identifierQuoteString + alias + identifierQuoteString);
        }
      }
      List<FromItem> fromItems = query.getFromClause().getItems();
      for (FromItem item : fromItems) {
        String alias = item.getAlias();
        if (needsQuoting(alias, identifierQuoteString)) {
          item.setAlias(identifierQuoteString + alias + identifierQuoteString);
        }
      }
    }
  }
  return query;
}

  @Override
  public Query clone() {
    final Query q = new Query();
    q.setMaxRows(_maxRows);
    q.setFirstRow(_firstRow);
    q.getSelectClause().setDistinct(_selectClause.isDistinct());
    for (FromItem item : _fromClause.getItems()) {
      q.from(item.clone());
    }
    for (SelectItem item : _selectClause.getItems()) {
      q.select(item.clone(q));
    }
    for (FilterItem item : _whereClause.getItems()) {
      q.where(item.clone());
    }
    for (GroupByItem item : _groupByClause.getItems()) {
      q.groupBy(item.clone());
    }
    for (FilterItem item : _havingClause.getItems()) {
      q.having(item.clone());
    }
    for (OrderByItem item : _orderByClause.getItems()) {
      q.orderBy(item.clone());
    }
    return q;
  }
}