package liquibase.sqlgenerator.core;

 import liquibase.database.Database;

 import liquibase.database.typeconversion.TypeConverterFactory;

 import liquibase.database.structure.Column;

 import liquibase.database.structure.Table;

 import liquibase.exception.ValidationErrors;

 import liquibase.sql.Sql;

 import liquibase.sql.UnparsedSql;

 import liquibase.sqlgenerator.SqlGenerator;

 import liquibase.sqlgenerator.SqlGeneratorChain;

 import liquibase.statement.core.AddDefaultValueStatement;

 public class AddDefaultValueGenerator extends AbstractSqlGenerator<AddDefaultValueStatement> {

     public ValidationErrors validate(AddDefaultValueStatement addDefaultValueStatement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         ValidationErrors validationErrors = new ValidationErrors();

         validationErrors.checkRequiredField("defaultValue", addDefaultValueStatement.getDefaultValue());

         validationErrors.checkRequiredField("columnName", addDefaultValueStatement.getColumnName());

         validationErrors.checkRequiredField("tableName", addDefaultValueStatement.getTableName());

         return validationErrors;

     }

     public Sql[] generateSql(AddDefaultValueStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {

         Object defaultValue = statement.getDefaultValue();

         return new Sql[] { new UnparsedSql("ALTER TABLE "

                 + database.escapeTableName(statement.getSchemaName(), statement.getTableName())

                 + " ALTER COLUMN  "

                 + database.escapeColumnName(statement.getSchemaName(), statement.getTableName(),

                         statement.getColumnName())

                 + " SET DEFAULT "

                 + TypeConverterFactory.getInstance().findTypeConverter(database).getDataType(defaultValue)

                         .convertObjectToString(defaultValue, database), new Column().setTable(

                 new Table(statement.getTableName()).setSchema(statement.getSchemaName())).setName(

                 statement.getColumnName())) };

     }

 }