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.snapshot.SnapshotGeneratorFactory;
import liquibase.statement.SqlStatement;
import liquibase.statement.core.DropColumnStatement;
import liquibase.statement.core.ReorganizeTableStatement;
import liquibase.structure.core.Column;
import liquibase.structure.core.Index;
import liquibase.structure.core.PrimaryKey;
import liquibase.structure.core.Table;
import liquibase.util.StringUtils;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Drops an existing column from a table.
*/
@DatabaseChange(name = "dropColumn", description = "Drop existing column(s)", priority = ChangeMetaData.PRIORITY_DEFAULT, appliesTo = "column")
public class DropColumnChange extends AbstractChange implements ChangeWithColumns<ColumnConfig> {
private String catalogName;
private String schemaName;
private String tableName;
private String columnName;
private List<ColumnConfig> columns = new ArrayList<ColumnConfig>();
@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", requiredForDatabase = "none")
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 (isMultiple()) {
return generateMultipeColumns(database);
} else {
return generateSingleColumn(database);
}
}
private SqlStatement[] generateMultipeColumns(Database database) {
List<SqlStatement> statements = new ArrayList<SqlStatement>();
List<DropColumnStatement> dropStatements = new ArrayList<DropColumnStatement>();
for (ColumnConfig column : columns) {
if (database instanceof SQLiteDatabase) {
statements.addAll(Arrays.asList(generateStatementsForSQLiteDatabase(database, column.getName())));
} else {
dropStatements.add(new DropColumnStatement(getCatalogName(), getSchemaName(), getTableName(), column.getName()));
}
}
if (dropStatements.size() == 1) {
statements.add(dropStatements.get(0));
} else {
statements.add(new DropColumnStatement(dropStatements));
}
if (database instanceof DB2Database) {
statements.add(new ReorganizeTableStatement(getCatalogName(), getSchemaName(), getTableName()));
}
return statements.toArray(new SqlStatement[statements.size()]);
}
private SqlStatement[] generateSingleColumn(Database database) {
if (database instanceof SQLiteDatabase) {
// return special statements for SQLite databases
return generateStatementsForSQLiteDatabase(database, getColumnName());
}
List<SqlStatement> statements = new ArrayList<SqlStatement>();
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()]);
}
@Override
public ChangeStatus checkStatus(Database database) {
try {
return new ChangeStatus().assertComplete(!SnapshotGeneratorFactory.getInstance().has(new Column(Table.class, getCatalogName(), getSchemaName(), getTableName(), getColumnName()), database), "Column exists");
} catch (Exception e) {
return new ChangeStatus().unknown(e);
}
}
private SqlStatement[] generateStatementsForSQLiteDatabase(Database database, final String columnName) {
// 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<SqlStatement> statements = new ArrayList<SqlStatement>();
// 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(columnName);
}
public boolean copyThisColumn(ColumnConfig column) {
return !column.getName().equals(columnName);
}
public boolean createThisIndex(Index index) {
return !index.getColumns().contains(columnName);
}
};
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() {
if (isMultiple()) {
List<String> names = new ArrayList<String>(columns.size());
for (ColumnConfig column : columns) {
names.add(column.getName());
}
return "Columns " + StringUtils.join(names, ",") + " dropped from " + getTableName();
} else {
return "Column " + getTableName() + "." + getColumnName() + " dropped";
}
}
@Override
public String getSerializedObjectNamespace() {
return STANDARD_CHANGELOG_NAMESPACE;
}
@Override
public Object getSerializableFieldValue(String field) {
Object value = super.getSerializableFieldValue(field);
if (field.equals("columns") && ((List) value).size() == 0) {
return null;
}
return value;
}
@Override
public void addColumn(ColumnConfig column) {
columns.add(column);
}
@Override
@DatabaseChangeProperty(description = "Columns to be dropped.", requiredForDatabase = "none")
public List<ColumnConfig> getColumns() {
return columns;
}
@Override
public void setColumns(List<ColumnConfig> columns) {
this.columns = columns;
}
private boolean isMultiple() {
return columns != null && !columns.isEmpty();
}
}