Public Types | Public Member Functions | Static Public Member Functions | Protected Member Functions | Related Functions

Gnome::Gda::DataModel Class Reference
[Data Models]

Abstract DataModel (Base class for all DataModels). More...

Inheritance diagram for Gnome::Gda::DataModel:
Inheritance graph
[legend]
Collaboration diagram for Gnome::Gda::DataModel:
Collaboration graph
[legend]

List of all members.

Public Types

typedef Glib::ListHandle
< Value, ValueTraits > 
ValueList
typedef Glib::SListHandle
< Value, ValueTraits > 
ValueSList

Public Member Functions

virtual ~DataModel ()
GdaDataModel* gobj ()
 Provides access to the underlying C GObject.
const GdaDataModel* gobj () const
 Provides access to the underlying C GObject.
void freeze ()
 Disables notifications of changes on the given data model.
void thaw ()
 Re-enables notifications of changes on the given data model.
int get_n_rows () const
int get_n_columns () const
int get_column_index (const Glib::ustring& name)
 Get the index of the first column named name in model.
Glib::RefPtr< Columndescribe_column (int col)
 Queries the underlying data model implementation for a description of a given column.
Glib::RefPtr< const Columndescribe_column (int col) const
 Queries the underlying data model implementation for a description of a given column.
Glib::ustring get_column_title (int col) const
void set_column_title (int col, const Glib::ustring& title)
 Sets the title of the given col in model.
Value get_value_at (int col, int row) const
 Retrieves the data stored in the given position (identified by the col and row parameters) on a data model.
Value get_typed_value_at (int col, int row, GType expected_type, bool nullok) const
 Upon errors 0 will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.
ValueAttribute get_attributes_at (int col, int row)
 Get the attributes of the value stored at (row, col) in model, which is an ORed value of Gda::ValueAttribute flags.
Glib::RefPtr< DataModelItercreate_iter ()
 Creates a new iterator object Gda::DataModelIter object which can be used to iterate through rows in model.
bool set_value_at (int col, int row, const Value&value)
 Modifies a value in model, at ( col, row).
bool set_values (int row, const ValueList& values)
 In a similar way to set_value_at(), this method modifies a data model's contents by setting several values at once.
DataModelAccessFlags get_access_flags () const
 Get the attributes of model such as how to access the data it contains if it's modifiable, etc.
int append_values (const ValueList& values)
 Appends a row to the given data model.
bool append_row ()
 Appends a row to the data model (the new row will possibly have 0 values for all columns, or some other values depending on the data model implementation)
bool remove_row (int row)
 Removes a row from the data model.
int get_row_from_values (const ValueSList& values, const Glib::ArrayHandle< int >& cols_index)
 Returns the first row where all the values in values at the columns identified at cols_index match.
void send_hint (DataModelHint hint, const Value& hint_value)
 Sends a hint to the data model.
Glib::ustring export_to_string (DataModelIOFormat format, const Glib::ArrayHandle< int >& cols, const Glib::ArrayHandle< int >& rows, const Glib::RefPtr< Set >& options)
 Exports data contained in model to the a string; the format is specified using the format argument.
bool export_to_file (DataModelIOFormat format, const std::string& file, const Glib::ArrayHandle< int >& cols, const Glib::ArrayHandle< int >& rows, const Glib::RefPtr< Set >& options)
 Exports data contained in model to the file; the format is specified using the format argument.
bool import_from_model (const Glib::RefPtr< DataModel >& from, bool overwrite, GHashTable* cols_trans)
 Copy the contents of the from data model to the to data model.
bool import_from_string (const Glib::ustring&string, GHashTable* cols_trans, const Glib::RefPtr< const Set >& options)
 Loads the data from string into model.
bool import_from_file (const std::string& file, GHashTable* cols_trans, const Glib::RefPtr< const Set >& options)
 Imports data contained in the file file into model; the format is detected.
void dump (FILE* to_stream) const
 Dumps a textual representation of the model to the to_stream stream.
Glib::ustring dump_as_string () const
 Dumps a textual representation of the model into a new string.
void set_column_name (int col, const Glib::ustring& name)
 Sets the name of the given col in model, and if its title is not set, also sets the title to name.
Glib::ustring get_column_name (int col) const
bool iter_move_next_default (const Glib::RefPtr< DataModelIter >& iter)
bool iter_move_prev_default (const Glib::RefPtr< DataModelIter >& iter)
bool iter_move_to_row_default (const Glib::RefPtr< DataModelIter >& iter, int row)
Glib::SignalProxy1< void, int > signal_row_inserted ()
Glib::SignalProxy1< void, int > signal_row_updated ()
Glib::SignalProxy1< void, int > signal_row_removed ()
Glib::SignalProxy0< void > signal_reset ()
Glib::SignalProxy0< void > signal_changed ()

Static Public Member Functions

static void add_interface (GType gtype_implementer)

Protected Member Functions

virtual void on_row_inserted (int row)
virtual void on_row_updated (int row)
virtual void on_row_removed (int row)
virtual void on_reset ()
virtual void on_changed ()

Related Functions

(Note that these are not member functions.)


Glib::RefPtr
< Gnome::Gda::DataModel
wrap (GdaDataModel* object, bool take_copy=false)
 A Glib::wrap() method for this object.

Detailed Description

Abstract DataModel (Base class for all DataModels).

A DataModel represents an array of values organized in rows and columns. All the data in the same column have the same type, and all the data in each row have the same semantic meaning. The DataModel is actually an interface implemented by other objects to support various kinds of data storage and operations.

Depending on the real implementation, the contents of data models may be modified by the user by using functions provided by the model. The actual operations that a data model permits can be discovered using the get_access_flags() method.

Again, depending on the real implementation, data retreival can be done either by accessing direct random values located by their row and column, or by using a DataModelIter cursor, or both. Use the get_access_flags() method to discover how the data model can be accessed. Note that a Datamodel which can be accessed in a random way can also be accessed using cursors (and several cusrors may be used at the same time), whereas a data model which can only be accessed using cursors can only have one cursor for iterating.

Random access data models are easier to use since picking a value is very simple by using the get_value_at(), but they consume more memory since all the accessible values must generally be present in memory even if they are not used. Thus, if a data model must handle large quantities of data, it is generally wiser to use a data model which can be only accessed using a cursor.

As a side note there are also data models which wrap other data models such as:


Member Typedef Documentation


Constructor & Destructor Documentation

virtual Gnome::Gda::DataModel::~DataModel (  ) [virtual]

Member Function Documentation

static void Gnome::Gda::DataModel::add_interface ( GType  gtype_implementer ) [static]
bool Gnome::Gda::DataModel::append_row (  )

Appends a row to the data model (the new row will possibly have 0 values for all columns, or some other values depending on the data model implementation)

Upon errors -1 will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Returns:
The number of the added row, or -1 if an error occurred.
int Gnome::Gda::DataModel::append_values ( const ValueList values )

Appends a row to the given data model.

If any value in values is actually 0, then it is considered as a default value.

Upon errors -1 will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
valuesList of Value* representing the row to add. The length must match model's column count. These Value are value-copied (the user is still responsible for freeing them).
Returns:
The number of the added row, or -1 if an error occurred.
Glib::RefPtr<DataModelIter> Gnome::Gda::DataModel::create_iter (  )

Creates a new iterator object Gda::DataModelIter object which can be used to iterate through rows in model.

Depending on the data model's implementation, a new Gda::DataModelIter object may be created, or a reference to an already existing Gda::DataModelIter may be returned.

If a new Gda::DataModelIter is created, then the row it represents is undefined.

For models which can be accessed randomly, any row can be set using Gda::DataModelIter::move_to_row(), and for models which are accessible sequentially only then use Gda::DataModelIter::move_next() (and Gda::DataModelIter::move_prev() if supported).

Returns:
A Gda::DataModelIter object, or 0 if an error occurred.
Glib::RefPtr<Column> Gnome::Gda::DataModel::describe_column ( int  col )

Queries the underlying data model implementation for a description of a given column.

That description is returned in the form of a Gda::Column structure, which contains all the information about the given column in the data model.

WARNING: the returned Gda::Column object belongs to the model model and and should not be destroyed; any modification will affect the whole data model.

Parameters:
colColumn number.
Returns:
The description of the column.
Glib::RefPtr<const Column> Gnome::Gda::DataModel::describe_column ( int  col ) const

Queries the underlying data model implementation for a description of a given column.

That description is returned in the form of a Gda::Column structure, which contains all the information about the given column in the data model.

WARNING: the returned Gda::Column object belongs to the model model and and should not be destroyed; any modification will affect the whole data model.

Parameters:
colColumn number.
Returns:
The description of the column.
void Gnome::Gda::DataModel::dump ( FILE *  to_stream ) const

Dumps a textual representation of the model to the to_stream stream.

The following environment variables can affect the resulting output: <itemizedlist> <listitem>

GDA_DATA_MODEL_DUMP_ROW_NUMBERS: if set, the first column of the output will contain row numbers

</listitem> <listitem>

GDA_DATA_MODEL_DUMP_ATTRIBUTES: if set, also dump the data model's columns' types and value's attributes

</listitem> <listitem>

GDA_DATA_MODEL_DUMP_TITLE: if set, also dump the data model's title

</listitem> <listitem>

GDA_DATA_MODEL_DUMP_NULL_AS_EMPTY: if set, replace the '0' string with an empty string for 0 values

</listitem> </itemizedlist>

Parameters:
to_streamWhere to dump the data model.
Glib::ustring Gnome::Gda::DataModel::dump_as_string (  ) const

Dumps a textual representation of the model into a new string.

The following environment variables can affect the resulting output: <itemizedlist> <listitem>

GDA_DATA_MODEL_DUMP_ROW_NUMBERS: if set, the first column of the output will contain row numbers

</listitem> <listitem>

GDA_DATA_MODEL_DUMP_TITLE: if set, also dump the data model's title

</listitem> <listitem>

GDA_DATA_MODEL_DUMP_NULL_AS_EMPTY: if set, replace the '0' string with an empty string for 0 values

</listitem> </itemizedlist>

Returns:
A new string.
bool Gnome::Gda::DataModel::export_to_file ( DataModelIOFormat  format,
const std::string file,
const Glib::ArrayHandle< int > &  cols,
const Glib::ArrayHandle< int > &  rows,
const Glib::RefPtr< Set >&  options 
)

Exports data contained in model to the file; the format is specified using the format argument.

Specifically, the parameters in the list can be:

  • SEPARATOR: a string value of which the first character is used as a separator in case of CSV export. -"NAME: a string value used to name the exported data if the export format is XML.
  • OVERWRITE: a boolean value which tells if the file must be over-written if it already exists.
Parameters:
formatThe format in which to export data.
fileThe filename to export to.
colsAn array containing which columns of will be exported.
rowsAn array containing which rows of will be exported.
optionsList of options for the export.
Returns:
true if no error occurred.
Glib::ustring Gnome::Gda::DataModel::export_to_string ( DataModelIOFormat  format,
const Glib::ArrayHandle< int > &  cols,
const Glib::ArrayHandle< int > &  rows,
const Glib::RefPtr< Set >&  options 
)

Exports data contained in model to the a string; the format is specified using the format argument.

Specifically, the parameters in the list can be:

  • SEPARATOR: a string value of which the first character is used as a separator in case of CSV export. -"NAME: a string value used to name the exported data if the export format is XML.
  • OVERWRITE: a boolean value which tells if the file must be over-written if it already exists.
Parameters:
formatThe format in which to export data.
colsAn array containing which columns of will be exported.
rowsAn array containing which rows of will be exported.
optionsList of options for the export.
Returns:
The string.
void Gnome::Gda::DataModel::freeze (  )

Disables notifications of changes on the given data model.

To re-enable notifications again, you should call the gda_data_model_thaw function.

DataModelAccessFlags Gnome::Gda::DataModel::get_access_flags (  ) const

Get the attributes of model such as how to access the data it contains if it's modifiable, etc.

Returns:
An ORed value of Gda::DataModelAccessFlags flags.
ValueAttribute Gnome::Gda::DataModel::get_attributes_at ( int  col,
int  row 
)

Get the attributes of the value stored at (row, col) in model, which is an ORed value of Gda::ValueAttribute flags.

As a special case, if row is -1, then the attributes returned correspond to a "would be" value if a row was added to model.

Parameters:
colA valid column number.
rowA valid row number, or -1.
Returns:
The attributes as an ORed value of Gda::ValueAttribute.
int Gnome::Gda::DataModel::get_column_index ( const Glib::ustring name )

Get the index of the first column named name in model.

Parameters:
nameA column name.
Returns:
The column index, or -1 if no column named name was found.
Glib::ustring Gnome::Gda::DataModel::get_column_name ( int  col ) const
Since libgdamm 3.2:
Parameters:
colColumn number.
Returns:
The name for the given column in a data model object.
Glib::ustring Gnome::Gda::DataModel::get_column_title ( int  col ) const
Parameters:
colColumn number.
Returns:
The title for the given column in a data model object.
int Gnome::Gda::DataModel::get_n_columns (  ) const
Returns:
The number of columns in the given data model.
int Gnome::Gda::DataModel::get_n_rows (  ) const
Returns:
The number of rows in the given data model, or -1 if the number of rows is not known.
int Gnome::Gda::DataModel::get_row_from_values ( const ValueSList values,
const Glib::ArrayHandle< int > &  cols_index 
)

Returns the first row where all the values in values at the columns identified at cols_index match.

If the row can't be identified, then returns -1;

NOTE: the cols_index array MUST contain a column index for each value in values

Parameters:
valuesA list of Value values (no 0 is allowed).
cols_indexAn array of int containing the column number to match each value of values.
Returns:
The requested row number, of -1 if not found.
Value Gnome::Gda::DataModel::get_typed_value_at ( int  col,
int  row,
GType  expected_type,
bool  nullok 
) const

Upon errors 0 will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

This method is similar to get_value_at(), except that it also allows one to specify the expected Type of the value to get: if the data model returned a Value of a type different than the expected one, then this method returns 0 and an error code.

Note:
the same limitations and usage instructions apply as for get_value_at().

Upon errors false will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
colA valid column number.
rowA valid row number.
expected_typeThe expected data type of the returned value.
nullokIf true, then 0 values (value of type Gda::TYPE_<tt>0) will not generate any error.
Returns:
A Value containing the value stored in the given position, or 0 on error (out-of-bound position, wrong data type, etc).
Value Gnome::Gda::DataModel::get_value_at ( int  col,
int  row 
) const

Retrieves the data stored in the given position (identified by the col and row parameters) on a data model.

Upon errors 0 will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

This is the main function for accessing data in a model which allows random access to its data. To access data in a data model using a cursor, use a Gda::DataModelIter object, obtained using create_iter().

Note:
the returned Value must not be modified directly (unexpected behaviours may occur if you do so).
the returned value may become invalid as soon as any Libgda part is executed again, which means if you want to keep the value, a copy must be made, however it will remain valid as long as the only Libgda usage is calling get_value_at() for different values of the same row.

If you want to modify a value stored in a Gda::DataModel, use the set_value_at() or set_values() methods.

Upon errors 0 will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
colA valid column number.
rowA valid row number.
Returns:
A Value containing the value stored in the given position, or 0 on error (out-of-bound position, etc).
GdaDataModel* Gnome::Gda::DataModel::gobj (  ) [inline]
const GdaDataModel* Gnome::Gda::DataModel::gobj (  ) const [inline]
bool Gnome::Gda::DataModel::import_from_file ( const std::string file,
GHashTable *  cols_trans,
const Glib::RefPtr< const Set >&  options 
)

Imports data contained in the file file into model; the format is detected.

Upon errors false will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
fileThe filename to import from.
cols_transA HashTable for columns translating, or 0, see import_from_model().
optionsList of options for the export.
Returns:
true if no error occurred.
bool Gnome::Gda::DataModel::import_from_model ( const Glib::RefPtr< DataModel >&  from,
bool  overwrite,
GHashTable *  cols_trans 
)

Copy the contents of the from data model to the to data model.

The copy stops as soon as an error orrurs.

The cols_trans is a hash table for which keys are to columns numbers and the values are the corresponding column numbers in the from data model. To set the values of a column in to to 0, create an entry in the hash table with a negative value.

Upon errors false will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
fromThe source Gda::DataModel.
overwritetrue if to is completely overwritten by from's data, and false if from's data is appended to to.
cols_transA HashTable for columns translating, or 0.
Returns:
true if no error occurred.
bool Gnome::Gda::DataModel::import_from_string ( const Glib::ustring string,
GHashTable *  cols_trans,
const Glib::RefPtr< const Set >&  options 
)

Loads the data from string into model.

Upon errors false will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
stringThe string to import data from.
cols_transA hash table containing which columns of model will be imported, or 0 for all columns, see import_from_model().
optionsList of options for the export.
Returns:
true if no error occurred.
bool Gnome::Gda::DataModel::iter_move_next_default ( const Glib::RefPtr< DataModelIter >&  iter )
bool Gnome::Gda::DataModel::iter_move_prev_default ( const Glib::RefPtr< DataModelIter >&  iter )
bool Gnome::Gda::DataModel::iter_move_to_row_default ( const Glib::RefPtr< DataModelIter >&  iter,
int  row 
)
virtual void Gnome::Gda::DataModel::on_changed (  ) [protected, virtual]
virtual void Gnome::Gda::DataModel::on_reset (  ) [protected, virtual]
virtual void Gnome::Gda::DataModel::on_row_inserted ( int  row ) [protected, virtual]
virtual void Gnome::Gda::DataModel::on_row_removed ( int  row ) [protected, virtual]
virtual void Gnome::Gda::DataModel::on_row_updated ( int  row ) [protected, virtual]
bool Gnome::Gda::DataModel::remove_row ( int  row )

Removes a row from the data model.

Upon errors false will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
rowThe row number to be removed.
Returns:
true if successful, false otherwise.
void Gnome::Gda::DataModel::send_hint ( DataModelHint  hint,
const Value hint_value 
)

Sends a hint to the data model.

The hint may or may not be handled by the data model, depending on its implementation

Parameters:
hintA hint to send to the model.
hint_valueAn optional value to specify the hint, or 0.
void Gnome::Gda::DataModel::set_column_name ( int  col,
const Glib::ustring name 
)

Sets the name of the given col in model, and if its title is not set, also sets the title to name.

Since libgdamm 3.2:
Parameters:
colColumn number.
nameName for the given column.
void Gnome::Gda::DataModel::set_column_title ( int  col,
const Glib::ustring title 
)

Sets the title of the given col in model.

Parameters:
colColumn number.
titleTitle for the given column.
bool Gnome::Gda::DataModel::set_value_at ( int  col,
int  row,
const Value value 
)

Modifies a value in model, at ( col, row).

Upon errors false will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
colColumn number.
rowRow number.
valueA Value (not 0).
Returns:
true if the value in the data model has been updated and no error occurred.
bool Gnome::Gda::DataModel::set_values ( int  row,
const ValueList values 
)

In a similar way to set_value_at(), this method modifies a data model's contents by setting several values at once.

If any value in values is actually 0, then the value in the corresponding column is left unchanged.

Upon errors false will be returned and error will be assigned a Error from the Gda::DATA_MODEL_ERROR domain.

Parameters:
rowRow number.
valuesA list of Value, one for at most the number of columns of model.
Returns:
true if the value in the data model has been updated and no error occurred.
Glib::SignalProxy0< void > Gnome::Gda::DataModel::signal_changed (  )
Prototype:
void on_my_changed()
Glib::SignalProxy0< void > Gnome::Gda::DataModel::signal_reset (  )
Prototype:
void on_my_reset()
Glib::SignalProxy1< void,int > Gnome::Gda::DataModel::signal_row_inserted (  )
Prototype:
void on_my_row_inserted(int row)
Glib::SignalProxy1< void,int > Gnome::Gda::DataModel::signal_row_removed (  )
Prototype:
void on_my_row_removed(int row)
Glib::SignalProxy1< void,int > Gnome::Gda::DataModel::signal_row_updated (  )
Prototype:
void on_my_row_updated(int row)
void Gnome::Gda::DataModel::thaw (  )

Re-enables notifications of changes on the given data model.


Friends And Related Function Documentation

Glib::RefPtr< Gnome::Gda::DataModel > wrap ( GdaDataModel *  object,
bool  take_copy = false 
) [related]

A Glib::wrap() method for this object.

Parameters:
objectThe C instance.
take_copyFalse if the result should take ownership of the C instance. True if it should take a new copy or ref.
Returns:
A C++ instance that wraps this C instance.

The documentation for this class was generated from the following file: