## GdaVconnectionDataModel GdaVconnectionDataModel — Virtual connection based on a list of GdaDataModel |

## Synopsis

                        GdaVconnectionDataModel;
                        GdaVconnectionDataModelSpec;
    GList*              (*GdaVconnectionDataModelCreateColumnsFunc)
                                                            (GdaVconnectionDataModelSpec *);
    GdaDataModel*       (*GdaVconnectionDataModelCreateModelFunc)
                                                            (GdaVconnectionDataModelSpec *);
    gboolean            gda_vconnection_data_model_add      (GdaVconnectionDataModel *cnc,
                                                             GdaVconnectionDataModelSpec *spec,
                                                             GDestroyNotify spec_free_func,
                                                             const gchar *table_name,
                                                             GError **error);
    gboolean            gda_vconnection_data_model_add_model
                                                            (GdaVconnectionDataModel *cnc,
                                                             GdaDataModel *model,
                                                             const gchar *table_name,
                                                             GError **error);
    gboolean            gda_vconnection_data_model_remove   (GdaVconnectionDataModel *cnc,
                                                             const gchar *table_name,
                                                             GError **error);
    const gchar*        gda_vconnection_data_model_get_table_name
                                                            (GdaVconnectionDataModel *cnc,
                                                             GdaDataModel *model);
    GdaDataModel*       gda_vconnection_data_model_get_model
                                                            (GdaVconnectionDataModel *cnc,
                                                             const gchar *table_name);
    void                gda_vconnection_data_model_foreach  (GdaVconnectionDataModel *cnc,
                                                             GdaVConnectionDataModelFunc func,
                                                             gpointer data);

## Object Hierarchy

      GObject
       +----GdaConnection
             +----GdaVirtualConnection
                   +----GdaVconnectionDataModel
                         +----GdaVconnectionHub

## Description

the GdaVconnectionDataModel is a virtual connection in which GdaDataModel data models can bas added or removed, each representing a table in the connection.

Note that virtual connections have some inherent limitations [2]due to the implementation.

## Details

### GdaVconnectionDataModel

    typedef struct _GdaVconnectionDataModel GdaVconnectionDataModel;

### GdaVconnectionDataModelSpec

    typedef struct {
    	GdaDataModel                             *data_model;
    	GdaVconnectionDataModelCreateColumnsFunc  create_columns_func;
    	GdaVconnectionDataModelCreateModelFunc    create_model_func;
    };
    #define GDA_VCONNECTION_DATA_MODEL_SPEC(x) ((GdaVconnectionDataModelSpec*)(x))

    typedef void (*GdaVConnectionDataModelFunc) (GdaDataModel *model, const gchar *table_name, gpointer data);

    struct _GdaVconnectionDataModel {
    	GdaVirtualConnection            connection;
    	GdaVconnectionDataModelPrivate *priv;
    } GdaVconnectionDataModelSpec;

### GdaVconnectionDataModelCreateColumnsFunc ()

    GList*              (*GdaVconnectionDataModelCreateColumnsFunc)
                                                            (GdaVconnectionDataModelSpec *);

`Param1` : |
Returns : |

### GdaVconnectionDataModelCreateModelFunc ()

    GdaDataModel*       (*GdaVconnectionDataModelCreateModelFunc)
                                                            (GdaVconnectionDataModelSpec *);

`Param1` : |
Returns : |

### gda_vconnection_data_model_add ()

    gboolean            gda_vconnection_data_model_add      (GdaVconnectionDataModel *cnc,
                                                             GdaVconnectionDataModelSpec *spec,
                                                             GDestroyNotify spec_free_func,
                                                             const gchar *table_name,
                                                             GError **error);

Create a new virtual table named `table_name` in `cnc`. The contents of that new table is dictated by what's in `spec`.

If there is just one GdaDataModel to make appear as a table then the `gda_vconnection_data_model_add_model()` method is easier to use.

`cnc` : | a GdaVconnectionDataModel connection
`spec` : | a GdaVconnectionDataModelSpec structure
`spec_free_func` : | function to call when freeing `spec`, or `NULL`
`table_name` : | the name of the table
`error` : | a place to store errors, or `NULL`
Returns : | TRUE if no error occurred

### gda_vconnection_data_model_add_model ()

    gboolean            gda_vconnection_data_model_add_model
                                                            (GdaVconnectionDataModel *cnc,
                                                             GdaDataModel *model,
                                                             const gchar *table_name,
                                                             GError **error);

Make `model` appear as a table named `table_name` in the `cnc` connection (as if a "CREATE TABLE..." statement was executed, except that the data contained within `model` is actually used when `table_name`'s contents is read or written).

For a more general approach, see the `gda_vconnection_data_model_add()` method.

`cnc` : | a GdaVconnectionDataModel connection
`model` : | a GdaDataModel
`table_name` : | the name of the table
`error` : | a place to store errors, or `NULL`
Returns : | TRUE if no error occurred

### gda_vconnection_data_model_remove ()

    gboolean            gda_vconnection_data_model_remove   (GdaVconnectionDataModel *cnc,
                                                             const gchar *table_name,
                                                             GError **error);

Remove the table named `table_name` in the `cnc` connection (as if a "DROP TABLE..." statement was executed, except that no data gets destroyed as the associated data model remains the same).

`cnc` : | a GdaVconnectionDataModel connection
`table_name` : | the name of the table to remove from `cnc`
`error` : | a place to store errors, or `NULL`
Returns : | TRUE if no error occurred

### gda_vconnection_data_model_get_table_name ()

    const gchar*        gda_vconnection_data_model_get_table_name
                                                            (GdaVconnectionDataModel *cnc,
                                                             GdaDataModel *model);

Find the name of the table associated to `model` in `cnc`

`cnc` : | a GdaVconnectionDataModel connection
`model` : | a GdaDataModel representing a table within `cnc`
Returns : | the table name, or `NULL` if not found

### gda_vconnection_data_model_get_model ()

    GdaDataModel*       gda_vconnection_data_model_get_model
                                                            (GdaVconnectionDataModel *cnc,
                                                             const gchar *table_name);

Find the GdaDataModel object representing the `table_name` table in `cnc`

`cnc` : | a GdaVconnectionDataModel connection
`table_name` : | a table name within `cnc`
Returns : | the GdaDataModel, or `NULL` if no table named `table_name` exists

### gda_vconnection_data_model_foreach ()

    void                gda_vconnection_data_model_foreach  (GdaVconnectionDataModel *cnc,
                                                             GdaVConnectionDataModelFunc func,
                                                             gpointer data);

Call `func` for each GdaDataModel represented as a table in `cnc`.

`cnc` : | a GdaVconnectionDataModel connection
`func` : | a GdaVConnectionDataModelFunc function pointer
`data` : | data to pass to `cunc` calls

## See Also

The GdaVproviderDataModel provider to use to create such connection objects.

[2] As virtual connections are implemented using SQLite's virtual table features, the SQL dialect which can be used is the SQLite one (see the SQL as Understood By SQLite page), and there are a few limitations inherent to this implementation (see link for more information).

Also note that it is possible to create temporary tables in virtual connections using "CREATE TEMP TABLE..." statements, but the contents of such tables will be lost once the connection is closed.