Session: Backend connections.
[Backends: Permanent storage for QOF entities.]

---

Detailed Description

The QOF Session encapsulates a connection to a storage backend. That is, it manages the connection to a persistant data store; whereas the backend is the thing that performs the actual datastore access.

This class provides several important services:

1) It resolves and loads the appropriate backend, based on the URL.

2) It reports backend errors (e.g. network errors, storage corruption errors) through a single, backend-independent API.

3) It reports non-error events received from the backend.

4) It helps manage global dataset locks. For example, for the file backend, the lock prevents multiple users from editing the same file at the same time, thus avoiding lost data due to race conditions. Thus, an open session implies that the associated file is locked.

5) Misc utilities, such as a search path for the file to be edited, and/or other URL resolution utilities. This should simplify install & maintenance problems for naive users who may not have a good grasp on what a file system is, or where they want to keep their data files.

6) In the future, this class is probably a good place to manage a portion of the user authentication process, and hold user credentials/cookies/keys/tokens. This is because at the coarsest level, authorization can happen at the datastore level: i.e. does this user even have the authority to connect to and open this datastore?

A brief note about books & sessions: A book encapsulates the datasets manipulated by QOF. A book holds the actual data. By contrast, the session mediates the connection between a book (the thing that lives in virtual memory in the local process) and the datastore (the place where book data lives permanently, e.g., file, database).

In the current design, a session may hold multiple books. For now, exactly what this means is somewhat vague, and code in various places makes some implicit assumptions: first, only one book is 'current' and open for editing. Next, its assumed that all of the books in a session are related in some way. i.e. that they are all earlier accounting periods of the currently open book. In particular, the backends probably make that assumption, in order to store the different accounting periods in a clump so that one can be found, given another.

If you want multiple books that are unrelated to each other, use multiple sessions.

The session now calls QofBackendProvider->check_data_type to check that the incoming path contains data that the backend provider can open. The backend provider should also check if it can contact it's storage media (disk, network, server, etc.) and abort if it can't. Malformed file URL's would be handled the same way.

Files
file	qofsession.h
	Encapsulates a connection to a backend (persistent store).
Copying entities between sessions.
Only certain backends can cope with selective copying of entities and only fully defined QOF entities can be copied between sessions - see the QOF Serialisation Format (QSF) documentation (qsf_write_file) for more information. The recommended backend for the new session is QSF or a future SQL backend. Using any of these entity copy functions sets a flag in the backend that this is now a partial QofBook. See Reference: Referring to entities outside a partial book.. When you save a session containing a partial QofBook, the session will check that the backend is able to handle the partial book. If not, the backend will be replaced by one that can handle partial books, preferably one using the same access_method. Currently, this means that a book using the GnuCash XML v2 file backend will be switched to QSF. Copied entities are identical to the source entity, all parameters defined with QofAccessFunc and QofSetterFunc in QOF are copied and the GUID of the original QofEntity is set in the new entity. Sessions containing copied entities are intended for use as mechanisms for data export. It is acceptable to add entities to new_session in batches. Note that any of these calls will fail if an entity already exists in new_session with the same GUID as any entity to be copied. To merge a whole QofBook or where there is any possibility of collisions or requirement for user intervention, see Merge: Merging QofBook structures
gboolean	qof_entity_copy_to_session (QofSession *new_session, QofEntity *original)
	Copy a single QofEntity to another session.
gboolean	qof_entity_copy_list (QofSession *new_session, GList *entity_list)
	Copy a GList of entities to another session.
gboolean	qof_entity_copy_coll (QofSession *new_session, QofCollection *entity_coll)
	Copy a QofCollection of entities.
gboolean	qof_entity_copy_coll_r (QofSession *new_session, QofCollection *coll)
	Recursively copy a collection of entities to a session.
gboolean	qof_entity_copy_one_r (QofSession *new_session, QofEntity *ent)
	Recursively copy a single entity to a new session.
Event Handling
gboolean	qof_session_events_pending (QofSession *session)
gboolean	qof_session_process_events (QofSession *session)
Defines
#define	QOF_MOD_SESSION   "qof-session"
#define	QOF_STDOUT   "file:"
	Allow session data to be printed to stdout.
Typedefs
typedef struct _QofSession	QofSession
typedef void(*	QofPercentageFunc )(const gchar *message, gdouble percent)
Functions
QofSession *	qof_session_new (void)
void	qof_session_destroy (QofSession *session)
void	qof_session_swap_data (QofSession *session_1, QofSession *session_2)
void	qof_session_begin (QofSession *session, const gchar *book_id, gboolean ignore_lock, gboolean create_if_nonexistent)
void	qof_session_load (QofSession *session, QofPercentageFunc percentage_func)
void	qof_session_add_book (QofSession *session, QofBook *book)
QofBook *	qof_session_get_book (QofSession *session)
const gchar *	qof_session_get_file_path (QofSession *session)
const gchar *	qof_session_get_url (QofSession *session)
gboolean	qof_session_not_saved (QofSession *session)
gboolean	qof_session_save_may_clobber_data (QofSession *session)
void	qof_session_save (QofSession *session, QofPercentageFunc percentage_func)
void	qof_session_end (QofSession *session)
void	qof_session_add_close_hook (GFunc fn, gpointer data)
void	qof_session_call_close_hooks (QofSession *session)

---

Define Documentation

#define QOF_STDOUT   "file:"

Allow session data to be printed to stdout.

book_id can't be NULL and we do need to have an access_method, so use one to solve the other.

To print a session to stdout, use qof_session_begin. Example:

qof_session_begin(session,QOF_STDOUT,TRUE,FALSE);

When you call qof_session_save(session, NULL), the output will appear on stdout and can be piped or redirected to other processes.

Currently, only the QSF backend supports writing to stdout, other backends may return a QofBackendError.

Definition at line 386 of file qofsession.h.

---

Typedef Documentation

typedef void(* QofPercentageFunc)(const gchar *message, gdouble percent)

The qof_session_load() method causes the QofBook to be made ready to to use with this URL/datastore. When the URL points at a file, then this routine would load the data from the file. With remote backends, e.g. network or SQL, this would load only enough data to make the book actually usable; it would not cause *all* of the data to be loaded.

XXX the current design tries to accomodate multiple calls to 'load' for each session, each time wiping out the old books; this seems wrong to me, and should be restricted to allow only one load per session.

Definition at line 168 of file qofsession.h.

---

Function Documentation

gboolean qof_entity_copy_coll	(	QofSession *	new_session,
		QofCollection *	entity_coll
	)

Copy a QofCollection of entities.

The QofBook in the new_session must not contain any entities with the same GUID as any entities in the collection - there is no support for handling collisions - instead, use Merge: Merging QofBook structures

Parameters:

	new_session	- the target session
	entity_coll	- a QofCollection of any QofIdType.

Returns:

FALSE, without copying, if new_session contains any entities with the same GUID. Otherwise TRUE.

Definition at line 737 of file qofsession.c.

{
    QofSession *session;
    gboolean success;
    GList *ref_list;
    GList *ent_list;
};

static void
recurse_collection_cb (QofEntity * ent, gpointer user_data)
{
    struct recurse_s *store;

    if (user_data == NULL)
    {
        return;
    }
    store = (struct recurse_s *) user_data;
    if (!ent || !store)
    {
        return;
    }
    store->success = qof_entity_copy_to_session (store->session, ent);
    if (store->success)
    {
        store->ent_list = g_list_append (store->ent_list, ent);

gboolean qof_entity_copy_coll_r	(	QofSession *	new_session,
		QofCollection *	coll
	)

Recursively copy a collection of entities to a session.

Note:

This function creates a partial QofBook. See qof_entity_copy_to_session for more information.

The QofBook in the new_session must not contain any entities with the same GUID as any entities to be copied - there is no support for handling collisions - instead, use Merge: Merging QofBook structures

Objects can be defined solely in terms of QOF data types or as a mix of data types and other objects, which may in turn include other objects. These references can be copied recursively down to the third level. See QofEntityReference.

Note:

This is a deep recursive copy - every referenced entity is copied to the new session, including all parameters. The starting point is all entities in the top level collection. It can take some time.

Parameters:

	coll	A QofCollection of entities that may or may not have references.
	new_session	The QofSession to receive the copied entities.

Returns:

TRUE on success; if any individual copy fails, returns FALSE. Note : Some entities may have been copied successfully even if one of the references fails to copy.

Definition at line 938 of file qofsession.c.

{
    const gchar *libdir;
    const gchar *filename;
    const gchar *init_fcn;
};

/* All available QOF backends need to be described here
and the last entry must be three NULL's.
Remember: Use the libdir from the current build environment
and use JUST the module name without .so - .so is not portable! */
struct backend_providers backend_list[] = {
    {QOF_LIB_DIR, QSF_BACKEND_LIB, QSF_MODULE_INIT},
    {QOF_LIB_DIR, "libqof-backend-sqlite", "qof_sqlite_provider_init"},
#ifdef HAVE_GDA
    {QOF_LIB_DIR, "libqof-backend-gda", "qof_gda_provider_init"},
#endif
#ifdef HAVE_DWI

gboolean qof_entity_copy_list	(	QofSession *	new_session,
		GList *	entity_list
	)

Copy a GList of entities to another session.

The QofBook in the new_session must not contain any entities with the same GUID as any of the source entities - there is no support for handling collisions, instead use Merge: Merging QofBook structures

Note that the GList (e.g. from qof_sql_query_run) can contain QofEntity pointers of any QofIdType, in any sequence. As long as all members of the list are QofEntity*, and all GUID's are unique, the list can be copied.

Parameters:

	new_session	- the target session
	entity_list	- a GList of QofEntity pointers of any type(s).

Returns:

FALSE, without copying, if new_session contains any entities with the same GUID. Otherwise TRUE.

Definition at line 715 of file qofsession.c.

    {
        return FALSE;
    }
    qof_event_suspend ();
    qecd.param_list = NULL;
    qecd.new_session = new_session;
    qof_book_set_partial (qof_session_get_book (qecd.new_session));
    qof_collection_foreach (entity_coll, qof_entity_coll_foreach, &qecd);
    qof_class_param_foreach (qof_collection_get_type (entity_coll),
        qof_entity_param_cb, &qecd);
    qof_collection_foreach (entity_coll, qof_entity_coll_copy, &qecd);
    if (qecd.param_list != NULL)
    {
        g_slist_free (qecd.param_list);
    }
    qof_event_resume ();
    return TRUE;
}

gboolean qof_entity_copy_one_r	(	QofSession *	new_session,
		QofEntity *	ent
	)

Recursively copy a single entity to a new session.

Copy the single entity and all referenced entities to the second level.

Only entities that are directly referenced by the top level entity are copied.

This is a deep copy - all parameters of all referenced entities are copied. If the top level entity has no references, this is identical to qof_entity_copy_to_session.

Parameters:

	ent	A single entity that may or may not have references.
	new_session	The QofSession to receive the copied entities.

Returns:

TRUE on success; if any individual copy fails, returns FALSE. Note : Some entities may have been copied successfully even if one of the references fails to copy.

Definition at line 962 of file qofsession.c.

    {NULL, NULL, NULL}
};

static void
qof_session_load_backend (QofSession * session, gchar *access_method)
{
    GSList *p;
    GList *node;
    QofBackendProvider *prov;
    QofBook *book;
    gint num;
    gboolean prov_type;
    gboolean (*type_check) (const gchar *);

    ENTER (" list=%d", g_slist_length (provider_list));
    prov_type = FALSE;
    if (NULL == provider_list)
    {
        for (num = 0; backend_list[num].filename != NULL; num++)
        {
            if (!qof_load_backend_library (backend_list[num].libdir,
                    backend_list[num].filename,
                    backend_list[num].init_fcn))
            {
                PWARN (" failed to load %s from %s using %s",
                    backend_list[num].filename, backend_list[num].libdir,
                    backend_list[num].init_fcn);

gboolean qof_entity_copy_to_session	(	QofSession *	new_session,
		QofEntity *	original
	)

Copy a single QofEntity to another session.

Checks first that no entity in the session book contains the GUID of the source entity.

Parameters:

	new_session	- the target session
	original	- the QofEntity* to copy

Returns:

FALSE without copying if the session contains an entity with the same GUID already, otherwise TRUE.

Definition at line 683 of file qofsession.c.

{
    QofEntityCopyData *qecd;

    if (!new_session || !entity_list)
        return FALSE;
    ENTER (" list=%d", g_list_length (entity_list));
    qecd = g_new0 (QofEntityCopyData, 1);
    qof_event_suspend ();
    qecd->param_list = NULL;
    qecd->new_session = new_session;
    qof_book_set_partial (qof_session_get_book (new_session));
    g_list_foreach (entity_list, qof_entity_list_foreach, qecd);
    qof_event_resume ();
    if (qecd->error)
        PWARN (" some/all entities in the list could not be copied.");
    g_free (qecd);
    LEAVE (" ");
    return TRUE;
}

gboolean
qof_entity_copy_coll (QofSession * new_session,
    QofCollection * entity_coll)
{

void qof_session_add_book	(	QofSession *	session,
		QofBook *	book
	)

The qof_session_add_book() allows additional books to be added to a session. XXX Under construction, clarify the following when done: XXX There must already be an open book in the session already!? XXX Only one open book at a time per session is allowed!? XXX each book gets its own unique backend ???

Definition at line 148 of file qofsession.c.

{
    GList *node;
    if (!session)
        return;

    ENTER (" sess=%p book=%p", session, addbook);

    /* See if this book is already there ... */
    for (node = session->books; node; node = node->next)
    {
        QofBook *book = node->data;
        if (addbook == book)
            return;
    }

    if ('y' == addbook->book_open)
    {
        /* hack alert -- someone should free all the books in the list,
         * but it should probably not be us ... since the books backends
         * should be shutdown first, etc */
/* XXX this should probably be an error XXX */
        g_list_free (session->books);
        session->books = g_list_append (NULL, addbook);
    }
    else
    {
/* XXX Need to tell the backend to add a book as well */
        session->books = g_list_append (session->books, addbook);
    }

    qof_book_set_backend (addbook, session->backend);
    LEAVE (" ");
}

void qof_session_add_close_hook	(	GFunc	fn,
		gpointer	data
	)

Register a function to be called just before a session is closed.

Parameters:

	fn	The function to be called. The function definition must be func(gpointer session, gpointer user_data);
	data	The data to be passed to the function.

Definition at line 69 of file qofsession.c.

{
    GHook *hook;

    if (session_closed_hooks == NULL)
    {
        session_closed_hooks = malloc (sizeof (GHookList)); /* LEAKED */
        g_hook_list_init (session_closed_hooks, sizeof (GHook));
    }

    hook = g_hook_alloc (session_closed_hooks);
    if (!hook)
        return;

    hook->func = (GHookFunc) fn;
    hook->data = data;
    g_hook_append (session_closed_hooks, hook);
}

void qof_session_begin	(	QofSession *	session,
		const gchar *	book_id,
		gboolean	ignore_lock,
		gboolean	create_if_nonexistent
	)

The qof_session_begin () method begins a new session. It takes as an argument the book id. The book id must be a string in the form of a URI/URL. The access method specified depends on the loaded backends. In the absence of a customised backend, only QSF XML would be accepted). Paths may be relative or absolute. If the path is relative; that is, if the argument is "file:somefile.xml" then the current working directory is assumed. Customised backends can choose to search other, application-specific, directories as well.

The 'ignore_lock' argument, if set to TRUE, will cause this routine to ignore any global-datastore locks (e.g. file locks) that it finds. If set to FALSE, then file/database-global locks will be tested and obeyed.

If the datastore exists, can be reached (e.g over the net), connected to, opened and read, and a lock can be obtained then a lock will be obtained. Note that multi-user datastores (e.g. the SQL backend) typically will not need to get a global lock, and thus, the user will not be locked out. That's the whole point of 'multi-user'.

If the file/database doesn't exist, and the create_if_nonexistent flag is set to TRUE, then the database is created.

If an error occurs, it will be pushed onto the session error stack, and that is where it should be examined.

Definition at line 1111 of file qofsession.c.

    {
        gchar * msg;

        msg = g_strdup_printf (_("Unable to locate a "
        "suitable backend for '%s' - please check "
        "you have specified an access method "
        "like file: or sqlite:"), book_id);
        qof_error_set (session, qof_error_register
            (msg, FALSE));
        DEBUG (" msg=%s", msg);
        LEAVE (" BAD: no backend: sess=%p book-id=%s",
            session, book_id ? book_id : "(null)");
        g_free (msg);
        return;
    }

    /* If there's a begin method, call that. */
    if (session->backend->session_begin)
    {
        (session->backend->session_begin) (session->backend, session,
            session->book_id, ignore_lock, create_if_nonexistent);
        PINFO (" Done running session_begin on backend");
        if (qof_error_check(session) != QOF_SUCCESS)
        {
            g_free (session->book_id);
            session->book_id = NULL;
            LEAVE (" backend error ");
            return;
        }
    }
    qof_error_clear (session);
    LEAVE (" sess=%p book-id=%s", session, book_id ? book_id : "(null)");
}

/* ============================================================== */

void
qof_session_load (QofSession * session, QofPercentageFunc percentage_func)
{
    QofBook *newbook, *ob;
    QofBookList *oldbooks, *node;
    QofBackend *be;

    if (!session)
        return;
    if ((!session->book_id) ||
        (0 == safe_strcasecmp(session->book_id, QOF_STDOUT)))
        return;

    ENTER (" sess=%p book_id=%s", session, session->book_id
        ? session->book_id : "(null)");

    /* At this point, we should are supposed to have a valid book 
     * id and a lock on the file. */

    oldbooks = session->books;

    /* XXX why are we creating a book here? I think the books
     * need to be handled by the backend ... especially since 
     * the backend may need to load multiple books ... XXX. FIXME.
     */
    newbook = qof_book_new ();
    session->books = g_list_append (NULL, newbook);
    PINFO (" new book=%p", newbook);

    qof_error_clear (session);

    /* This code should be sufficient to initialize *any* backend,
     * whether http, postgres, or anything else that might come along.
     * Basically, the idea is that by now, a backend has already been
     * created & set up.  At this point, we only need to get the
     * top-level account group out of the backend, and that is a
     * generic, backend-independent operation.
     */
    be = session->backend;
    qof_book_set_backend (newbook, be);

    /* Starting the session should result in a bunch of accounts
     * and currencies being downloaded, but probably no transactions;
     * The GUI will need to do a query for that.
     */
    if (be)
    {
        be->percentage = percentage_func;

        if (be->load)
        {

void qof_session_call_close_hooks

(

QofSession *

session

)

Call all registered session close hooks, informing them that the specified session is about to be closed.

Parameters:

session

A pointer to the session being closed.

Definition at line 89 of file qofsession.c.

{
    GHook *hook;
    GFunc fn;

    if (session_closed_hooks == NULL)
        return;

    hook = g_hook_first_valid (session_closed_hooks, FALSE);
    while (hook)
    {
        fn = (GFunc) hook->func;
        fn (session, hook->data);
        hook = g_hook_next_valid (session_closed_hooks, hook, FALSE);
    }
}

void qof_session_end

(

QofSession *

session

)

The qof_session_end() method will release the session lock. For the file backend, it will *not* save the data to a file. Thus, this method acts as an "abort" or "rollback" primitive. However, for other backends, such as the sql backend, the data would have been written out before this, and so this routines wouldn't roll-back anything; it would just shut the connection.

Definition at line 1453 of file qofsession.c.

{
    GList *books_1, *books_2, *node;

    if (session_1 == session_2)
        return;
    if (!session_1 || !session_2)
        return;

    ENTER (" sess1=%p sess2=%p", session_1, session_2);

    books_1 = session_1->books;
    books_2 = session_2->books;

    session_1->books = books_2;
    session_2->books = books_1;

gboolean qof_session_events_pending

(

QofSession *

session

)

The qof_session_events_pending() method will return TRUE if the backend has pending events which must be processed to bring the engine up to date with the backend.

Definition at line 1546 of file qofsession.c.

const gchar* qof_session_get_file_path

(

QofSession *

session

)

The qof_session_get_file_path() routine returns the fully-qualified file path for the session. That is, if a relative or partial filename was for the session, then it had to have been fully resolved to open the session. This routine returns the result of this resolution. The path is always guaranteed to reside in the local file system, even if the session itself was opened as a URL. (currently, the filepath is derived from the url by substituting commas for slashes).

The qof_session_get_url() routine returns the url that was opened. URL's for local files take the form of file:/some/where/some/file.gml

Definition at line 192 of file qofsession.c.

{
    if (!session)
        return NULL;
    if (!session->backend)
        return NULL;
    return session->backend->fullpath;
}

gboolean qof_session_not_saved

(

QofSession *

session

)

The qof_session_not_saved() subroutine will return TRUE if any data in the session hasn't been saved to long-term storage.

gboolean qof_session_process_events

(

QofSession *

session

)

The qof_session_process_events() method will process any events indicated by the qof_session_events_pending() method. It returns TRUE if the engine was modified while engine events were suspended.

Definition at line 1559 of file qofsession.c.

void qof_session_save	(	QofSession *	session,
		QofPercentageFunc	percentage_func
	)

The qof_session_save() method will commit all changes that have been made to the session. For the file backend, this is nothing more than a write to the file of the current AccountGroup & etc. For the SQL backend, this is typically a no-op (since all data has already been written out to the database.

Todo:

check the access_method too, not in scope here, yet.

Definition at line 1299 of file qofsession.c.

        {
            prov = p->data;
            if (TRUE == prov->partial_book_supported)
            {
                /*  if((TRUE == prov->partial_book_supported) && 
                   (0 == strcasecmp (access_method, prov->access_method)))
                   { */
                if (NULL == prov->backend_new)
                    continue;
                /* Use the providers creation callback */
                session->backend = (*(prov->backend_new)) ();
                session->backend->provider = prov;
                if (session->backend->session_begin)
                {
                    /* Call begin - backend has been changed,
                       so make sure a file can be written,
                       use ignore_lock and create_if_nonexistent */
                    g_free (session->book_id);
                    session->book_id = NULL;
                    (session->backend->session_begin) (session->backend,
                        session, book_id, TRUE, TRUE);
                    PINFO
                        (" Done running session_begin on changed backend");
                    if (qof_error_check (session) != QOF_SUCCESS)
                    {
                        g_free (session->book_id);
                        session->book_id = NULL;
                        LEAVE (" changed backend error");
                        return;
                    }
                }
                /* Tell the books about the backend that they'll be using. */
                for (node = session->books; node; node = node->next)
                {
                    book = node->data;
                    qof_book_set_backend (book, session->backend);
                }
                p = NULL;
            }
            if (p)
            {
                p = p->next;
            }
        }
        if (!session->backend)
        {
            msg = g_strdup_printf (" failed to load backend");
            qof_error_set (session, qof_error_register
            (_("Failed to load backend, no suitable handler."), 
            FALSE));
            return;
        }
    }
    /* If there is a backend, and the backend is reachable
     * (i.e. we can communicate with it), then synchronize with 
     * the backend.  If we cannot contact the backend (e.g.
     * because we've gone offline, the network has crashed, etc.)
     * then give the user the option to save to the local disk. 
     *
     * hack alert -- FIXME -- XXX the code below no longer
     * does what the words above say.  This needs fixing.
     */
    be = session->backend;
    if (be)
    {
        for (node = session->books; node; node = node->next)
        {
            abook = node->data;
            /* if invoked as SaveAs(), then backend not yet set */
            qof_book_set_backend (abook, be);
            be->percentage = percentage_func;
            if (be->sync)
                (be->sync) (be, abook);
        }
        /* If we got to here, then the backend saved everything 
         * just fine, and we are done. So return. */
        /* Return the book_id to previous value. */
        qof_error_clear (session);
        LEAVE (" Success");
        return;
    }
    else
    {
        msg = g_strdup_printf (" failed to load backend");
        qof_error_set (session, qof_error_register
            (_("Failed to load backend, no suitable handler."), 
            FALSE));
    }
    LEAVE (" error -- No backend!");
}

/* ============================================================= */

void
qof_session_end (QofSession * session)
{
    if (!session)
        return;

    ENTER (" sess=%p book_id=%s", session, session->book_id
        ? session->book_id : "(null)");

    /* close down the backend first */
    if (session->backend && session->backend->session_end)
    {
        (session->backend->session_end) (session->backend);
    }

    qof_error_clear (session);

    g_free (session->book_id);
    session->book_id = NULL;

    LEAVE (" sess=%p book_id=%s", session, session->book_id
        ? session->book_id : "(null)");
}

void
qof_session_destroy (QofSession * session)
{
    GList *node;
    if (!session)
        return;

    ENTER (" sess=%p book_id=%s", session, session->book_id
        ? session->book_id : "(null)");

    qof_session_end (session);

    /* destroy the backend */
    qof_session_destroy_backend (session);

    for (node = session->books; node; node = node->next)
    {
        QofBook *book = node->data;
        qof_book_set_backend (book, NULL);
        qof_book_destroy (book);
    }

    session->books = NULL;
#ifndef QOF_DISABLE_DEPRECATED
    if (session == qof_session_get_current_session())
        qof_session_clear_current_session();
#endif

gboolean qof_session_save_may_clobber_data

(

QofSession *

session

)

Allows the backend to warn the user if a dataset already exists.

Definition at line 1286 of file qofsession.c.

        {
            change_backend = TRUE;
        }
    }
    if (change_backend == TRUE)
    {
        qof_session_destroy_backend (session);
        if (NULL == provider_list)
        {
            for (num = 0; backend_list[num].filename != NULL; num++)
            {

void qof_session_swap_data	(	QofSession *	session_1,
		QofSession *	session_2
	)

The qof_session_swap_data () method swaps the book of the two given sessions. It is useful for 'Save As' type functionality.

Definition at line 1512 of file qofsession.c.

---