Subclassing GdaDataSelect

Subclassing GdaDataSelect — Base class for all the data models returned by DBMS providers when a SELECT statement is executed

Synopsis


#include <providers-support/gda-data-select-priv.h>

                    GdaDataSelectClass;
void                gda_data_select_take_row            (GdaDataSelect *model,
                                                         GdaRow *row,
                                                         gint rownum);
GdaRow*             gda_data_select_get_stored_row      (GdaDataSelect *model,
                                                         gint rownum);
GdaConnection*      gda_data_select_get_connection      (GdaDataSelect *model);

void                gda_column_set_name                 (GdaColumn *column,
                                                         const gchar *name);
void                gda_column_set_description          (GdaColumn *column,
                                                         const gchar *title);
void                gda_column_set_dbms_type            (GdaColumn *column,
                                                         const gchar *dbms_type);
void                gda_column_set_g_type               (GdaColumn *column,
                                                         GType type);
void                gda_column_set_allow_null           (GdaColumn *column,
                                                         gboolean allow);
void                gda_column_set_auto_increment       (GdaColumn *column,
                                                         gboolean is_auto);
void                gda_column_set_position             (GdaColumn *column,
                                                         gint position);
void                gda_column_set_default_value        (GdaColumn *column,
                                                         const GValue *default_value);

gchar*              gda_alphanum_to_text                (gchar *text);
gchar*              gda_text_to_alphanum                (const gchar *text);

gboolean            gda_data_model_iter_move_next_default
                                                        (GdaDataModel *model,
                                                         GdaDataModelIter *iter);
gboolean            gda_data_model_iter_move_prev_default
                                                        (GdaDataModel *model,
                                                         GdaDataModelIter *iter);

void                gda_row_invalidate_value            (GdaRow *row,
                                                         GValue *value);
gboolean            gda_row_value_is_valid              (GdaRow *row,
                                                         GValue *value);

Description

All database providers should subclass this class when returning a data model after the execution of a SELECT statement. Specifically it has the following features:

  • Manages its list of GdaColumn using the list exported by the prepared statement object (GdaPStmt)

  • Allows random or cursor based access

  • Allows for efficient memory usage allowing the subclass to finely tune its memory usage

  • Provides a generic mechanism for writable data models

See the Virtual methods for recordsets section for more information about how to implement the virtual methods of the subclassed object.

This section documents the methods available for the database provider's implementations.

Details

GdaDataSelectClass

typedef struct {
	GObjectClass      parent_class;

	/* GDA_DATA_MODEL_ACCESS_RANDOM */
	gint             (*fetch_nb_rows) (GdaDataSelect *model);
	gboolean         (*fetch_random)  (GdaDataSelect *model, GdaRow **prow, gint rownum, GError **error);
	gboolean         (*store_all)     (GdaDataSelect *model, GError **error);

	/* GDA_STATEMENT_MODEL_CURSOR_* */
	gboolean         (*fetch_next)    (GdaDataSelect *model, GdaRow **prow, gint rownum, GError **error);
	gboolean         (*fetch_prev)    (GdaDataSelect *model, GdaRow **prow, gint rownum, GError **error);
	gboolean         (*fetch_at)      (GdaDataSelect *model, GdaRow **prow, gint rownum, GError **error);

	/* Padding for future expansion */
	void (*_gda_reserved1) (void);
	void (*_gda_reserved2) (void);
	void (*_gda_reserved3) (void);
	void (*_gda_reserved4) (void);
} GdaDataSelectClass;

GObjectClass parent_class;

 parent object class

fetch_nb_rows ()

 virtual method which must be implemented when access method is GDA_DATA_MODEL_ACCESS_RANDOM

fetch_random ()

 virtual method which must be implemented when access method is GDA_DATA_MODEL_ACCESS_RANDOM

store_all ()

fetch_next ()

 virtual method which must be implemented when access method is GDA_DATA_MODEL_ACCESS_CURSOR_FORWARD

fetch_prev ()

 virtual method which must be implemented when access method is GDA_DATA_MODEL_ACCESS_CURSOR_BACKWARD

fetch_at ()

 virtual method which can be implemented when access method is GDA_DATA_MODEL_ACCESS_CURSOR_FORWARD or GDA_DATA_MODEL_ACCESS_CURSOR_BACKWARD

_gda_reserved1 ()

_gda_reserved2 ()

_gda_reserved3 ()

_gda_reserved4 ()

gda_data_select_take_row ()

void                gda_data_select_take_row            (GdaDataSelect *model,
                                                         GdaRow *row,
                                                         gint rownum);

Stores row into model, externally advertized at row number rownum (if no row has been removed). The reference to row is stolen.

model :

 a GdaDataSelect data model

row :

 a GdaRow row

rownum :

 "external" advertized row number

gda_data_select_get_stored_row ()

GdaRow*             gda_data_select_get_stored_row      (GdaDataSelect *model,
                                                         gint rownum);

Get the GdaRow object stored within model at row rownum (without taking care of removed rows)

model :

 a GdaDataSelect data model

rownum :

 "external" advertized row number

Returns :

 the requested GdaRow, or NULL if not found

gda_data_select_get_connection ()

GdaConnection*      gda_data_select_get_connection      (GdaDataSelect *model);

Get a pointer to the GdaConnection object which was used when model was created (and which may be used internally by model).

model :

 a GdaDataSelect data model

Returns :

 a pointer to the GdaConnection, or NULL

gda_column_set_name ()

void                gda_column_set_name                 (GdaColumn *column,
                                                         const gchar *name);

Sets the name of column to name.

column :

 a GdaColumn.

name :

 the new name of column.

gda_column_set_description ()

void                gda_column_set_description          (GdaColumn *column,
                                                         const gchar *title);

Sets the column's description

column :

 a GdaColumn.

title :

 title name.

gda_column_set_dbms_type ()

void                gda_column_set_dbms_type            (GdaColumn *column,
                                                         const gchar *dbms_type);

Defines column's database type

column :

 a GdaColumn

dbms_type :

 a string

gda_column_set_g_type ()

void                gda_column_set_g_type               (GdaColumn *column,
                                                         GType type);

Sets the type of column to type.

column :

 a GdaColumn.

type :

 the new type of column.

gda_column_set_allow_null ()

void                gda_column_set_allow_null           (GdaColumn *column,
                                                         gboolean allow);

Sets the 'allow null' flag of the given column.

column :

 a GdaColumn.

allow :

 whether the given column should allows null values or not.

gda_column_set_auto_increment ()

void                gda_column_set_auto_increment       (GdaColumn *column,
                                                         gboolean is_auto);

Sets the auto increment flag for the given column.

column :

 a GdaColumn.

is_auto :

 auto increment status.

gda_column_set_position ()

void                gda_column_set_position             (GdaColumn *column,
                                                         gint position);

Sets the position of the column refer to in the containing data model.

column :

 a GdaColumn.

position :

 the wanted position of the column in the containing data model.

gda_column_set_default_value ()

void                gda_column_set_default_value        (GdaColumn *column,
                                                         const GValue *default_value);

Sets column's default GValue.

column :

 a GdaColumn.

default_value :

 default GValue for the column

gda_alphanum_to_text ()

gchar*              gda_alphanum_to_text                (gchar *text);

Does the opposite of gda_text_to_alphanum(), in the same string

text :

 a string

Returns :

 text if conversion succedded or NULL if an error occurred

gda_text_to_alphanum ()

gchar*              gda_text_to_alphanum                (const gchar *text);

The "encoding" consists in replacing non alphanumeric character with the string "__gdaXX" where XX is the hex. representation of the non alphanumeric char.

text :

Returns :

 a new string

gda_data_model_iter_move_next_default ()

gboolean            gda_data_model_iter_move_next_default
                                                        (GdaDataModel *model,
                                                         GdaDataModelIter *iter);

model :

iter :

Returns :

gda_data_model_iter_move_prev_default ()

gboolean            gda_data_model_iter_move_prev_default
                                                        (GdaDataModel *model,
                                                         GdaDataModelIter *iter);

model :

iter :

Returns :

gda_row_invalidate_value ()

void                gda_row_invalidate_value            (GdaRow *row,
                                                         GValue *value);

Marks value as being invalid. This method is mainly used by database providers' implementations to report any error while reading a value from the database.

row :

 a GdaRow

value :

 a GValue belonging to row (obtained with gda_row_get_value()).

gda_row_value_is_valid ()

gboolean            gda_row_value_is_valid              (GdaRow *row,
                                                         GValue *value);

Tells if value has been marked as being invalid by gda_row_invalidate_value(). This method is mainly used by database providers' implementations to report any error while reading a value from the database.

row :

 a GdaRow.

value :

 a GValue belonging to row (obtained with gda_row_get_value()).

Returns :

 TRUE if value is valid
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