DropUniqueConstraintChange.java

package liquibase.change.core;

import liquibase.change.*;
import liquibase.database.Database;
import liquibase.database.core.SybaseASADatabase;
import liquibase.snapshot.SnapshotGeneratorFactory;
import liquibase.statement.SqlStatement;
import liquibase.statement.core.DropUniqueConstraintStatement;
import liquibase.structure.core.Column;
import liquibase.structure.core.UniqueConstraint;

/**
 * Removes an existing unique constraint.
 */
@DatabaseChange(name="dropUniqueConstraint", description = "Drops an existing unique constraint", priority = ChangeMetaData.PRIORITY_DEFAULT, appliesTo = "uniqueConstraint")
public class DropUniqueConstraintChange extends AbstractChange {
    private String catalogName;
    private String schemaName;
    private String tableName;
    private String constraintName;
    /**
     * Sybase ASA does drop unique constraint not by name, but using list of the columns in unique clause.
     */
    private String uniqueColumns;

    @DatabaseChangeProperty(mustEqualExisting ="uniqueConstraint.table.catalog", since = "3.0")
    public String getCatalogName() {
        return catalogName;
    }

    public void setCatalogName(String catalogName) {
        this.catalogName = catalogName;
    }

    @DatabaseChangeProperty(mustEqualExisting ="uniqueConstraint.table.schema")
    public String getSchemaName() {
        return schemaName;
    }

    public void setSchemaName(String schemaName) {
        this.schemaName = schemaName;
    }

    @DatabaseChangeProperty(mustEqualExisting = "uniqueConstraint.table", description = "Name of the table to drop the unique constraint from")
    public String getTableName() {
        return tableName;
    }

    public void setTableName(String tableName) {
        this.tableName = tableName;
    }

    @DatabaseChangeProperty(mustEqualExisting = "uniqueConstraint", description = "Name of unique constraint to drop")
    public String getConstraintName() {
        return constraintName;
    }

    public void setConstraintName(String constraintName) {
        this.constraintName = constraintName;
    }

    @DatabaseChangeProperty(exampleValue = "name")
    public String getUniqueColumns() {
		return uniqueColumns;
	}

	public void setUniqueColumns(String uniqueColumns) {
		this.uniqueColumns = uniqueColumns;
	}

    @Override
    public SqlStatement[] generateStatements(Database database) {
        
//todo    	if (database instanceof SQLiteDatabase) {
//    		// return special statements for SQLite databases
//    		return generateStatementsForSQLiteDatabase(database);
//        }
        DropUniqueConstraintStatement statement = new DropUniqueConstraintStatement(getCatalogName(), getSchemaName(), getTableName(), getConstraintName());
    	if (database instanceof SybaseASADatabase) {
    		statement.setUniqueColumns(ColumnConfig.arrayFromNames(uniqueColumns));
    	}
    	return new SqlStatement[]{
			statement
        };
    }

    @Override
    public ChangeStatus checkStatus(Database database) {
        try {
            UniqueConstraint example = new UniqueConstraint(getConstraintName(), getCatalogName(), getSchemaName(), getTableName());
            if (getUniqueColumns() != null) {
                for (String column : getUniqueColumns().split("\\s*,\\s*")) {
                    example.addColumn(example.getColumns().size(), new Column(column));
                }
            }
            return new ChangeStatus().assertComplete(!SnapshotGeneratorFactory.getInstance().has(example, database), "Unique constraint exists");
        } catch (Exception e) {
            return new ChangeStatus().unknown(e);
        }
    }
//    private SqlStatement[] generateStatementsForSQLiteDatabase(Database database) {
//
//    	// SQLite does not support this ALTER TABLE operation until now.
//		// For more information see: http://www.sqlite.org/omitted.html.
//		// This is a small work around...
//
//    	// Note: The attribute "constraintName" is used to pass the column
//    	// name instead of the constraint name.
//
//    	List<SqlStatement> statements = new ArrayList<SqlStatement>();
//
//		// define alter table logic
//		AlterTableVisitor rename_alter_visitor = new AlterTableVisitor() {
//			public ColumnConfig[] getColumnsToAdd() {
//				return new ColumnConfig[0];
//			}
//			public boolean copyThisColumn(ColumnConfig column) {
//				return true;
//			}
//			public boolean createThisColumn(ColumnConfig column) {
//				if (column.getName().equals(getConstraintName())) {
//    				column.getConstraints().setUnique(false);
//    			}
//				return true;
//			}
//			public boolean createThisIndex(Index index) {
//				return true;
//			}
//		};
//
//    	try {
//    		// alter table
//			statements.addAll(SQLiteDatabase.getAlterTableStatements(
//					rename_alter_visitor,
//					database,getCatalogName(), getSchemaName(),getTableName()));
//    	} catch (Exception e) {
//			e.printStackTrace();
//		}
//
//    	return statements.toArray(new SqlStatement[statements.size()]);
//    }

    @Override
    public String getConfirmationMessage() {
        return "Unique constraint "+getConstraintName()+" dropped from "+getTableName();
    }

    @Override
    public String getSerializedObjectNamespace() {
        return STANDARD_CHANGELOG_NAMESPACE;
    }
}