## EDataFactory EDataFactory — An abstract base class for a backend-based server |

## Functions

EBackend * | e_data_factory_ref_backend ()
EBackend * | e_data_factory_ref_initable_backend ()
EBackendFactory * | e_data_factory_ref_backend_factory ()

## Types and Values

struct | EDataFactory
struct | EDataFactoryClass

## Includes

    #include <libebackend/libebackend.h>

## Description

## Functions

### e_data_factory_ref_backend ()

    EBackend *
    e_data_factory_ref_backend (EDataFactory *data_factory,
                                const gchar *hash_key,
                                ESource *source);

Returns either a newly-created or existing EBackend for ESource. The returned EBackend is referenced for thread-safety and must be unreferenced with `g_object_unref()` when finished with it.

The `data_factory` retains a weak reference to `backend` so it can return the same instance while `backend` is in use. When the last strong reference to `backend` is dropped, `data_factory` will lose its weak reference and will have to create a new EBackend instance the next time the same `hash_key` and `source` are requested.

If no suitable EBackendFactory exists, the function returns `NULL`.

#### Parameters

data_factory | an EDataFactory |
hash_key | hash key for an EBackendFactory |
source | an ESource |

#### Returns

an EBackend for `source` , or `NULL`

Since 3.6

### e_data_factory_ref_initable_backend ()

    EBackend *
    e_data_factory_ref_initable_backend (EDataFactory *data_factory,
                                         const gchar *hash_key,
                                         ESource *source,
                                         GCancellable *cancellable,
                                         GError **error);

Similar to `e_data_factory_ref_backend()`, but allows for backends that implement the GInitable interface so they can fail gracefully if they are unable to initialize critical resources, such as a cache database.

Returns either a newly-created or existing EBackend for ESource. The returned EBackend is referenced for thread-safety and must be unreferenced with `g_object_unref()` when finished with it.

If the newly-created backend implements the GInitable interface, then `g_initable_init()` is also called on it using `cancellable` and `error` .

The `data_factory` retains a weak reference to `backend` so it can return the same instance while `backend` is in use. When the last strong reference to `backend` is dropped, `data_factory` will lose its weak reference and will have to create a new EBackend instance the next time the same `hash_key` and `source` are requested.

If no suitable EBackendFactory exists, or if the EBackend fails to initialize, the function sets `error` and returns `NULL`.

#### Parameters

data_factory | an EDataFactory |
hash_key | hash key for an EBackendFactory |
source | an ESource |
cancellable | optional GCancellable object, or `NULL` |
error | return location for a GError, or `NULL` |

#### Returns

an EBackend for `source` , or `NULL`

Since 3.8

### e_data_factory_ref_backend_factory ()

    EBackendFactory *
    e_data_factory_ref_backend_factory (EDataFactory *data_factory,
                                        const gchar *hash_key);

Returns the EBackendFactory for `hash_key` , or `NULL` if no such factory is registered.

The returned EBackendFactory is referenced for thread-safety. Unreference the EBackendFactory with `g_object_unref()` when finished with it.

#### Parameters

data_factory | an EDataFactory |
hash_key | hash key for an EBackendFactory |

#### Returns

the EBackendFactory for `hash_key` , or `NULL`

Since 3.6

## Types and Values

### struct EDataFactory

    struct EDataFactory {
    	EDBusServer parent;
    	EDataFactoryPrivate *priv;
    };

Contains only private data that should be read and manipulated using the functions below.

Since 3.4

### struct EDataFactoryClass

    struct EDataFactoryClass {
    	EDBusServerClass parent_class;

    	GType backend_factory_type;

    	/* Signals */
    	void		(*backend_created) (EDataFactory *data_factory,
    						 EBackend *backend);

    	gpointer reserved[15];
    };