schemacrawler.loader.weakassociations.TableCandidateKeys Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of schemacrawler Show documentation

SchemaCrawler is an open-source Java API that makes working with database metadata as easy as working with plain old Java objects. SchemaCrawler is also a database schema discovery and comprehension, and schema documentation tool. You can search for database schema objects using regular expressions, and output the schema and data in a readable text format. The output is designed to be diff-ed against other database schemas.

There is a newer version: 16.22.3

Show newest version

/*
========================================================================
SchemaCrawler
http://www.schemacrawler.com
Copyright (c) 2000-2024, Sualeh Fatehi .
All rights reserved.
------------------------------------------------------------------------

SchemaCrawler is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SchemaCrawler and the accompanying materials are made available under
the terms of the Eclipse Public License v1.0, GNU General Public License
v3 or GNU Lesser General Public License v3.

You may elect to redistribute this code under any of these licenses.

The Eclipse Public License is available at:
http://www.eclipse.org/legal/epl-v10.html

The GNU General Public License v3 and the GNU Lesser General Public
License v3 are available at:
http://www.gnu.org/licenses/

========================================================================
*/

package schemacrawler.loader.weakassociations;

import static java.util.Objects.requireNonNull;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import schemacrawler.schema.Column;
import schemacrawler.schema.Index;
import schemacrawler.schema.IndexColumn;
import schemacrawler.schema.PrimaryKey;
import schemacrawler.schema.Table;
import schemacrawler.schema.TableConstraintColumn;

final class TableCandidateKeys implements Iterable {

  private final Table table;
  private final Set tableKeys;

  TableCandidateKeys(final Table table) {
    this.table = requireNonNull(table, "No table provided");
    tableKeys = new HashSet<>();
    listTableKeys(table);
  }

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

  @Override
  public String toString() {
    return String.format("%s: %s", table, tableKeys);
  }

  private void addColumnFromIndex(final Table table, final Index index) {
    final IndexColumn indexColumn = index.getColumns().get(0);
    table.lookupColumn(indexColumn.getName()).ifPresent(column -> tableKeys.add(column));
  }

  private void addColumnFromPrimaryKey(final Table table, final PrimaryKey primaryKey) {
    final TableConstraintColumn tableConstraintColumn = primaryKey.getConstrainedColumns().get(0);
    table.lookupColumn(tableConstraintColumn.getName()).ifPresent(column -> tableKeys.add(column));
  }

  private void listTableKeys(final Table table) {
    final PrimaryKey primaryKey = table.getPrimaryKey();
    if (primaryKey != null && primaryKey.getConstrainedColumns().size() == 1) {
      addColumnFromPrimaryKey(table, primaryKey);
    }

    for (final Index index : table.getIndexes()) {
      if (index != null && index.isUnique() && index.getColumns().size() == 1) {
        addColumnFromIndex(table, index);
      }
    }
  }
}