nz.co.gregs.dbvolution.actions.DBAction Maven / Gradle / Ivy
/*
* Copyright 2013 Gregory Graham.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package nz.co.gregs.dbvolution.actions;
import java.sql.SQLException;
import java.util.List;
import nz.co.gregs.dbvolution.DBRow;
import nz.co.gregs.dbvolution.databases.DBDatabase;
import nz.co.gregs.dbvolution.databases.definitions.DBDefinition;
import nz.co.gregs.dbvolution.datatypes.QueryableDatatype;
import nz.co.gregs.dbvolution.internal.properties.PropertyWrapper;
/**
* DBAction encapsulates the concept of permanent changes to the database.
*
*
* All DBActions are an immutable encapsulation of the action and row at the
* point in time. A DBAction will perform the same action, given the same
* DBDatabase, no matter what has happened since the creation of the DBAction.
*
*
* Usually you should use the methods {@link DBDatabase#delete(nz.co.gregs.dbvolution.DBRow...) }, {@link DBDatabase#update(nz.co.gregs.dbvolution.DBRow...) }, {@link DBDatabase#insert(nz.co.gregs.dbvolution.DBRow...)
* } to automatically execute the DBActions, update any DBRows that need
* updating, and return the performed DBActions as a DBActionList.
*
*
* However DBAction and it's subclasses provide more features for scripting
* particularly {@link DBDelete#getDeletes(nz.co.gregs.dbvolution.databases.DBDatabase, nz.co.gregs.dbvolution.DBRow...) }, {@link DBUpdate#getUpdates(nz.co.gregs.dbvolution.DBRow...)
* }, and {@link DBInsert#getInserts(nz.co.gregs.dbvolution.DBRow...) },
* allowing a series of changes to be created then executed in a single batch.
*
*
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* Patreon
*
* @author Gregory Graham
*/
public abstract class DBAction {
final DBRow row;
/**
* Standard action constructor.
*
*
* Saves a copy of the row to ensure immutability.
*
* @param the table that this action applies to.
* @param row the row or example that this action applies to.
*/
public DBAction(R row) {
super();
this.row = DBRow.copyDBRow(row);
}
/**
* Returns a DBActionList containing the changes required to revert the
* DBAction.
*
*
* Every action has an opposite reaction. This method supplies the actions
* require to revert the change enacted by the action.
*
*
* Revert actions are tricky to implement correctly, so be sure to check
* that the revert will produce the desired result.
*
*
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* Patreon
*
* @return a list of all the actions required to revert this action in the
* order they need to enacted.
*/
protected abstract DBActionList getRevertDBActionList();
/**
* Returns a DBActionList of the actions required to perform this DBAction.
*
*
* Actions are allowed to create sub-actions so all actions are returned as
* a DBActionList.
*
*
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* Patreon
*
* @return a DBActionList of this DBAction.
*/
protected abstract DBActionList getActions();
/**
* Returns a copy of the row supplied during creation.
*
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* Patreon
*
* @return the row
*/
protected DBRow getRow() {
return DBRow.copyDBRow(row);
}
/**
* Returns a string that can be used in the WHERE clause to identify the
* rows affected by this DBAction.
*
*
* Used internally during UPDATE and INSERT.
*
* @param row the row that will be used in the method
* @param db the database to execute the DBAction on
* Support DBvolution at
* Patreon
* @return a string representing the
*/
protected String getPrimaryKeySQL(DBDatabase db, DBRow row) {
final DBDefinition definition = db.getDefinition();
StringBuilder sqlString = new StringBuilder();
List> primaryKeys = row.getPrimaryKeys();
String separator = "(";
for (QueryableDatatype pk : primaryKeys) {
PropertyWrapper wrapper = row.getPropertyWrapperOf(pk);
String pkValue = (pk.hasChanged() ? pk.getPreviousSQLValue(definition) : pk.toSQLString(definition));
sqlString.append(separator)
.append(definition.formatColumnName(wrapper.columnName()))
.append(definition.getEqualsComparator())
.append(pkValue);
separator = definition.beginOrLine();
}
return sqlString.append(")").toString();
}
/**
* Returns a list of the SQL statements that this DBAction will produce for
* the specified database.
*
*
* Actions happen all by themselves but when you want to know what will
* actually happen, use this method to get a complete list of all the SQL
* required.
*
* @param db the database that the SQL must be appropriate for.
*
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* @return the list of SQL strings that equates to this action.
*/
public abstract List getSQLStatements(DBDatabase db);
/**
* Performs the DB execute and returns a list of all actions performed in the
* process.
*
*
* The supplied row will be changed by the action in an appropriate way,
* however the Action will contain an unchanged and unchangeable copy of the
* row for internal use.
*
* @param db the target database.
*
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* Patreon
* @return The complete list of all actions performed to complete this action
* on the database
* @throws SQLException Database operations may throw SQLExceptions
*/
public abstract DBActionList execute(DBDatabase db) throws SQLException;
public boolean requiresRunOnIndividualDatabaseBeforeCluster() {
return false;
}
public boolean runOnDatabaseDuringCluster(DBDatabase initialDatabase, DBDatabase next) {
return true;
}
}