liquibase.change.core.DropColumnChange Maven / Gradle / Ivy

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package liquibase.change.core;

import liquibase.change.*;
import liquibase.database.Database;
import liquibase.database.core.DB2Database;
import liquibase.database.core.SQLiteDatabase;
import liquibase.exception.ValidationErrors;
import liquibase.statement.SqlStatement;
import liquibase.statement.core.DropColumnStatement;
import liquibase.statement.core.ReorganizeTableStatement;
import liquibase.structure.core.Index;

import java.util.ArrayList;
import java.util.List;

/**
 * Drops an existing column from a table.
 */
@DatabaseChange(name="dropColumn", description = "Drop an existing column", priority = ChangeMetaData.PRIORITY_DEFAULT, appliesTo = "column")
public class DropColumnChange extends AbstractChange {

    private String catalogName;
    private String schemaName;
    private String tableName;
    private String columnName;

    @Override
    public boolean generateStatementsVolatile(Database database) {
        if (database instanceof SQLiteDatabase) {
            return true;
        }
        return super.generateStatementsVolatile(database);
    }

    @Override
    public boolean supports(Database database) {
        if (database instanceof SQLiteDatabase) {
            return true;
        }
        return super.supports(database);
    }

    @Override
    public ValidationErrors validate(Database database) {
        if (database instanceof SQLiteDatabase) {
            ValidationErrors validationErrors = new ValidationErrors();
            validationErrors.checkRequiredField("tableName", tableName);
            validationErrors.checkRequiredField("columnName", columnName);

            return validationErrors;
        }
        return super.validate(database);
    }

    @DatabaseChangeProperty(mustEqualExisting = "column", description = "Name of the column to drop")
    public String getColumnName() {
        return columnName;
    }

    public void setColumnName(String columnName) {
        this.columnName = columnName;
    }


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

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

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

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

    @DatabaseChangeProperty(mustEqualExisting = "column.relation", description = "Name of the table containing the column to drop")
    public String getTableName() {
        return tableName;
    }

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

    @Override
    public SqlStatement[] generateStatements(Database database) {
     
        if (database instanceof SQLiteDatabase) {
        	// return special statements for SQLite databases
    		return generateStatementsForSQLiteDatabase(database);
		}

        List statements = new ArrayList();

        statements.add(new DropColumnStatement(getCatalogName(), getSchemaName(), getTableName(), getColumnName()));
        if (database instanceof DB2Database) {
            statements.add(new ReorganizeTableStatement(getCatalogName(), getSchemaName(), getTableName()));
        }
        
        return statements.toArray(new SqlStatement[statements.size()]);
    }
    
    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...

    	List statements = new ArrayList();

		// define alter table logic
		SQLiteDatabase.AlterTableVisitor rename_alter_visitor = new SQLiteDatabase.AlterTableVisitor() {
			public ColumnConfig[] getColumnsToAdd() {
				return new ColumnConfig[0];
			}
			public boolean createThisColumn(ColumnConfig column) {
				return !column.getName().equals(getColumnName());
			}
			public boolean copyThisColumn(ColumnConfig column) {
				return !column.getName().equals(getColumnName());
			}
			public boolean createThisIndex(Index index) {
				return !index.getColumns().contains(getColumnName());
			}
		};

    	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 "Column " + getTableName() + "." + getColumnName() + " dropped";
    }
}