dk.eobjects.metamodel
Class QueryPostprocessDataContextStrategy

java.lang.Object
  dk.eobjects.metamodel.QueryPostprocessDataContextStrategy

All Implemented Interfaces:

IDataContextStrategy

Direct Known Subclasses:

AccessDataContextStrategy, CsvDataContextStrategy, DbaseDataContextStrategy, ExcelDataContextStrategy, XmlDataContextStrategy

public abstract class QueryPostprocessDataContextStrategy
extends java.lang.Object
implements IDataContextStrategy

Abstract DataContextStrategy for data sources that do not support SQL queries. Instead this superclass only requires that a subclass can materialize a single table at a time. Then the query will be executed by post processing data client-side.

Field Summary

protected org.apache.commons.logging.Log	_log
static java.lang.String	INFORMATION_SCHEMA_NAME

Constructor Summary

QueryPostprocessDataContextStrategy()

Method Summary

QueryPostprocessDataContextStrategy	autoTransformColumnTypes() Performs column type transformation for the whole schema
DataSet	executeQuery(Query query) Executes a query.
java.lang.String	getDefaultSchemaName()
protected abstract Schema	getMainSchema()
protected Schema	getMainSchemaInternal()
protected abstract java.lang.String	getMainSchemaName()
Schema	getSchemaByName(java.lang.String name)
java.lang.String[]	getSchemaNames()
DataSet	materializeFromItem(FromItem fromItem)
abstract DataSet	materializeMainSchemaTable(Table table, Column[] columns, int maxRows) Executes a simple one-table query against a table in the main schema of the subclasses of this class.
protected DataSet	materializeTable(Table table, Column[] columns, int maxRows)
void	setColumnTypeTransformer(Column column, ColumnTypeTransformer transformer)
void	setColumnTypeTransformer(java.lang.String qualifiedColumnName, ColumnTypeTransformer transformer)
QueryPostprocessDataContextStrategy	transformColumnTypes(Column... columns)
QueryPostprocessDataContextStrategy	transformColumnTypes(Table table)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

INFORMATION_SCHEMA_NAME

public static final java.lang.String INFORMATION_SCHEMA_NAME

See Also:

Constant Field Values

_log

protected final org.apache.commons.logging.Log _log

Constructor Detail

QueryPostprocessDataContextStrategy

public QueryPostprocessDataContextStrategy()

Method Detail

setColumnTypeTransformer

public void setColumnTypeTransformer(java.lang.String qualifiedColumnName,
                                     ColumnTypeTransformer transformer)

setColumnTypeTransformer

public void setColumnTypeTransformer(Column column,
                                     ColumnTypeTransformer transformer)

executeQuery

public DataSet executeQuery(Query query)

Description copied from interface: IDataContextStrategy

Executes a query.

Specified by:

executeQuery in interface IDataContextStrategy

Returns:

a dataset representing the result of the query.

transformColumnTypes

public QueryPostprocessDataContextStrategy transformColumnTypes(Table table)

transformColumnTypes

public QueryPostprocessDataContextStrategy transformColumnTypes(Column... columns)

autoTransformColumnTypes

public QueryPostprocessDataContextStrategy autoTransformColumnTypes()

Performs column type transformation for the whole schema

materializeFromItem

public DataSet materializeFromItem(FromItem fromItem)

materializeTable

protected DataSet materializeTable(Table table,
                                   Column[] columns,
                                   int maxRows)

getSchemaNames

public java.lang.String[] getSchemaNames()
                                  throws MetaModelException

Specified by:

getSchemaNames in interface IDataContextStrategy

Returns:

an array of schema names within this datastore.

Throws:

MetaModelException

getDefaultSchemaName

public java.lang.String getDefaultSchemaName()
                                      throws MetaModelException

Specified by:

getDefaultSchemaName in interface IDataContextStrategy

Returns:

the name of the default schema provided by this strategy or null if none is present or possible to deterministically tell.

Throws:

MetaModelException

getSchemaByName

public Schema getSchemaByName(java.lang.String name)
                       throws MetaModelException

Specified by:

getSchemaByName in interface IDataContextStrategy

Returns:

the schema with the specified name, or null if such a schema is not available

Throws:

MetaModelException

getMainSchemaInternal

protected Schema getMainSchemaInternal()

getMainSchema

protected abstract Schema getMainSchema()
                                 throws MetaModelException

Returns:

the main schema that subclasses of this class produce

Throws:

MetaModelException

getMainSchemaName

protected abstract java.lang.String getMainSchemaName()
                                               throws MetaModelException

Returns:

the name of the main schema that subclasses of this class produce

Throws:

MetaModelException

materializeMainSchemaTable

public abstract DataSet materializeMainSchemaTable(Table table,
                                                   Column[] columns,
                                                   int maxRows)

Executes a simple one-table query against a table in the main schema of the subclasses of this class.

Parameters:

table - the table to query

columns - the columns to include

maxRows - the maximum amount of rows needed or -1 if all rows are wanted.

Returns:

a dataset with the raw table content of the colums