Entity
[Class: Getting and setting entity values.]


Data Structures

struct  QofEntity_s

Files

file  qofid.h
 QOF entity type identification system.

Defines

#define QOF_ID_NONE   NULL
#define QOF_ID_NULL   "null"
#define QOF_ID_BOOK   "Book"
#define QOF_ID_SESSION   "Session"
#define QOF_ENTITY(object)   ((QofEntity *)(object))
#define QSTRCMP(da, db)
#define QOF_CHECK_TYPE(obj, type)
#define QOF_CHECK_CAST(obj, e_type, c_type)

Typedefs

typedef const gchar * QofIdType
typedef const gchar * QofIdTypeConst
typedef const gchar * QofLogModule
typedef struct QofEntity_s QofEntity
typedef struct QofCollection_s QofCollection

Functions

const GUID * qof_entity_get_guid (QofEntity *)

Collections of Entities

typedef void(* QofEntityForeachCB )(QofEntity *, gpointer user_data)
QofCollectionqof_collection_new (QofIdType type)
guint qof_collection_count (QofCollection *col)
void qof_collection_destroy (QofCollection *col)
QofIdType qof_collection_get_type (QofCollection *)
QofEntityqof_collection_lookup_entity (QofCollection *, const GUID *)
void qof_collection_foreach (QofCollection *, QofEntityForeachCB, gpointer user_data)
gpointer qof_collection_get_data (QofCollection *col)
void qof_collection_set_data (QofCollection *col, gpointer user_data)
gboolean qof_collection_is_dirty (QofCollection *col)

QOF Entity Initialization & Shutdown

void qof_entity_init (QofEntity *, QofIdType, QofCollection *)
void qof_entity_release (QofEntity *)

QOF_TYPE_COLLECT: Linking one entity to many of one type

Note:
These are NOT the same as the main collections in the book.
QOF_TYPE_COLLECT is a secondary collection, used to select entities of one object type as references of another entity.
See also:
QOF_TYPE_CHOICE.


gboolean qof_collection_add_entity (QofCollection *coll, QofEntity *ent)
 Add an entity to a QOF_TYPE_COLLECT.
gboolean qof_collection_merge (QofCollection *target, QofCollection *merge)
 Merge two QOF_TYPE_COLLECT of the same type.
gint qof_collection_compare (QofCollection *target, QofCollection *merge)
 Compare two secondary collections.
QofCollectionqof_collection_from_glist (QofIdType type, GList *glist)
 Create a secondary collection from a GList.

Detailed Description

This file defines an API that adds types to the GUID's. GUID's with types can be used to identify and reference typed entities.

The idea here is that a GUID can be used to uniquely identify some thing. By adding a type, one can then talk about the type of thing identified. By adding a collection, one can then work with a handle to a collection of things of a given type, each uniquely identified by a given ID. QOF Entities can be used independently of any other part of the system. In particular, Entities can be useful even if one is not using the Query ond Object parts of the QOF system.

Identifiers are globally-unique and permanent, i.e., once an entity has been assigned an identifier, it retains that same identifier for its lifetime. Identifiers can be encoded as hex strings.

GUID Identifiers are 'typed' with strings. The native ids used by QOF are defined below.

  1. An id with type QOF_ID_NONE does not refer to any entity.
  2. An id with type QOF_ID_NULL does not refer to any entity, and will never refer to any entity. =# An identifier with any other type may refer to an actual entity, but that is not guaranteed as that entity does not have to exist within the current book. (See PARTIAL_QOFBOOK). Also, creating a new entity from a data source involves creating a temporary GUID and then setting the value from the data source. If an id does refer to an entity, the type of the entity will match the type of the identifier.

If you have a type name, and you want to have a way of finding a collection that is associated with that type, then you must use Books.

Entities can refer to other entities as well as to the basic QOF types, using the qofclass parameters.


Define Documentation

#define QOF_CHECK_CAST ( obj,
e_type,
c_type   ) 

Value:

(                   \
  QOF_CHECK_TYPE((obj),(e_type)) ?                            \
  (c_type *) (obj) :                                          \
  (c_type *) ({                                               \
     g_log (G_LOG_DOMAIN, G_LOG_LEVEL_CRITICAL,               \
       "Error: Bad QofEntity at %s:%d", __FILE__, __LINE__);  \
     (obj);                                                   \
  }))
cast object to the indicated type, print error message if its bad

Definition at line 119 of file qofid.h.

#define QOF_CHECK_TYPE ( obj,
type   ) 

Value:

(((obj) != NULL) && \
  (0 == QSTRCMP((type),(((QofEntity *)(obj))->e_type))))
return TRUE if object is of the given type

Definition at line 114 of file qofid.h.

#define QOF_ENTITY ( object   )     ((QofEntity *)(object))

simple,cheesy cast but holds water for now

Definition at line 94 of file qofid.h.

#define QSTRCMP ( da,
db   ) 

Value:

({                \
  gint val = 0;                          \
  if ((da) && (db)) {                    \
    if ((da) != (db)) {                  \
      val = strcmp ((da), (db));         \
    }                                    \
  } else                                 \
  if ((!(da)) && (db)) {                 \
    val = -1;                            \
  } else                                 \
  if ((da) && (!(db))) {                 \
    val = 1;                             \
  }                                      \
  val; /* block assumes value of last statment */  \
})
Inline string comparision; compiler will optimize away most of this

Definition at line 97 of file qofid.h.


Typedef Documentation

typedef struct QofCollection_s QofCollection

QofCollection declaration

Parameters:
e_type QofIdType
is_dirty gboolean
hash_of_entities GHashTable
data gpointer, place where object class can hang arbitrary data

Definition at line 138 of file qofid.h.

typedef struct QofEntity_s QofEntity

QofEntity declaration

Definition at line 129 of file qofid.h.

typedef void(* QofEntityForeachCB)(QofEntity *, gpointer user_data)

Callback type for qof_entity_foreach

Definition at line 187 of file qofid.h.

typedef const gchar* QofIdType

QofIdType declaration

Definition at line 81 of file qofid.h.

typedef const gchar* QofIdTypeConst

QofIdTypeConst declaration

Definition at line 83 of file qofid.h.

typedef const gchar* QofLogModule

QofLogModule declaration

Definition at line 85 of file qofid.h.


Function Documentation

gboolean qof_collection_add_entity ( QofCollection coll,
QofEntity ent 
)

Add an entity to a QOF_TYPE_COLLECT.

Note:
These are NOT the same as the main collections in the book.
Entities can be freely added and merged across these secondary collections, they will not be removed from the original collection as they would by using qof_entity_insert_entity or qof_entity_remove_entity.

Definition at line 182 of file qofid.c.

00183 {
00184     QofEntity *e;
00185 
00186     e = NULL;
00187     if (!coll || !ent)
00188     {
00189         return FALSE;
00190     }
00191     if (guid_equal (&ent->guid, guid_null ()))
00192     {
00193         return FALSE;
00194     }
00195     g_return_val_if_fail (coll->e_type == ent->e_type, FALSE);
00196     e = qof_collection_lookup_entity (coll, &ent->guid);
00197     if (e != NULL)
00198     {
00199         return FALSE;
00200     }
00201     g_hash_table_insert (coll->hash_of_entities, &ent->guid, ent);
00202     qof_collection_mark_dirty (coll);
00203     return TRUE;
00204 }

gint qof_collection_compare ( QofCollection target,
QofCollection merge 
)

Compare two secondary collections.

Performs a deep comparision of the collections. Each QofEntity in each collection is looked up in the other collection, via the GUID.

Returns:
0 if the collections are identical or both are NULL otherwise -1 if target is NULL or either collection contains an entity with an invalid GUID or if the types of the two collections do not match, or +1 if merge is NULL or if any entity exists in one collection but not in the other.

Definition at line 264 of file qofid.c.

00265 {
00266     gint value;
00267 
00268     value = 0;
00269     if (!target && !merge)
00270         return 0;
00271     if (target == merge)
00272         return 0;
00273     if (!target && merge)
00274         return -1;
00275     if (target && !merge)
00276         return 1;
00277     if (target->e_type != merge->e_type)
00278         return -1;
00279     qof_collection_set_data (target, &value);
00280     qof_collection_foreach (merge, collection_compare_cb, target);
00281     value = *(gint *) qof_collection_get_data (target);
00282     if (value == 0)
00283     {
00284         qof_collection_set_data (merge, &value);
00285         qof_collection_foreach (target, collection_compare_cb, merge);
00286         value = *(gint *) qof_collection_get_data (merge);
00287     }
00288     return value;
00289 }

guint qof_collection_count ( QofCollection col  ) 

return the number of entities in the collection.

Definition at line 322 of file qofid.c.

00323 {
00324     guint c;
00325 
00326     c = g_hash_table_size (col->hash_of_entities);
00327     return c;
00328 }

void qof_collection_destroy ( QofCollection col  ) 

destroy the collection

XXX there should be a destroy notifier for this

Definition at line 132 of file qofid.c.

00133 {
00134     CACHE_REMOVE (col->e_type);
00135     g_hash_table_destroy (col->hash_of_entities);
00136     col->e_type = NULL;
00137     col->hash_of_entities = NULL;
00138     col->data = NULL; 
00139     g_free (col);
00140 }

void qof_collection_foreach ( QofCollection ,
QofEntityForeachCB  ,
gpointer  user_data 
)

Call the callback for each entity in the collection.

Definition at line 392 of file qofid.c.

00394 {
00395     struct _iterate qiter;
00396 
00397     g_return_if_fail (col);
00398     g_return_if_fail (cb_func);
00399 
00400     qiter.fcn = cb_func;
00401     qiter.data = user_data;
00402 
00403     g_hash_table_foreach (col->hash_of_entities, foreach_cb, &qiter);
00404 }

QofCollection* qof_collection_from_glist ( QofIdType  type,
GList *  glist 
)

Create a secondary collection from a GList.

Parameters:
type The QofIdType of the QofCollection and of all entities in the GList.
glist GList of entities of the same QofIdType.
Returns:
NULL if any of the entities fail to match the QofCollection type, else a pointer to the collection on success.

Definition at line 303 of file qofid.c.

00304 {
00305     QofCollection *coll;
00306     QofEntity *ent;
00307     GList *list;
00308 
00309     coll = qof_collection_new (type);
00310     for (list = glist; list != NULL; list = list->next)
00311     {
00312         ent = (QofEntity *) list->data;
00313         if (FALSE == qof_collection_add_entity (coll, ent))
00314         {
00315             return NULL;
00316         }
00317     }
00318     return coll;
00319 }

gpointer qof_collection_get_data ( QofCollection col  ) 

Store arbitrary object-defined data

XXX We need to add a callback for when the collection is being destroyed, so that the user has a chance to clean up anything that was put in the 'data' member here.

Definition at line 359 of file qofid.c.

00360 {
00361     return col ? col->data : NULL;
00362 }

QofIdType qof_collection_get_type ( QofCollection  ) 

return the type that the collection stores

Definition at line 146 of file qofid.c.

00147 {
00148     return col->e_type;
00149 }

gboolean qof_collection_is_dirty ( QofCollection col  ) 

Return value of 'dirty' flag on collection

Definition at line 333 of file qofid.c.

00334 {
00335     return col ? col->is_dirty : FALSE;
00336 }

QofEntity* qof_collection_lookup_entity ( QofCollection ,
const GUID *   
)

Find the entity going only from its guid

Definition at line 292 of file qofid.c.

00293 {
00294     QofEntity *ent;
00295     g_return_val_if_fail (col, NULL);
00296     if (guid == NULL)
00297         return NULL;
00298     ent = g_hash_table_lookup (col->hash_of_entities, guid);
00299     return ent;
00300 }

gboolean qof_collection_merge ( QofCollection target,
QofCollection merge 
)

Merge two QOF_TYPE_COLLECT of the same type.

Note:
NOT the same as the main collections in the book.
QOF_TYPE_COLLECT uses a secondary collection, independent of those in the book. Entities will not be removed from the original collection as when using qof_entity_insert_entity or qof_entity_remove_entity.

Definition at line 216 of file qofid.c.

00217 {
00218     if (!target || !merge)
00219     {
00220         return FALSE;
00221     }
00222     g_return_val_if_fail (target->e_type == merge->e_type, FALSE);
00223     qof_collection_foreach (merge, collection_merge_cb, target);
00224     return TRUE;
00225 }

QofCollection* qof_collection_new ( QofIdType  type  ) 

create a new collection of entities of type

Definition at line 121 of file qofid.c.

00122 {
00123     QofCollection *col;
00124     col = g_new0 (QofCollection, 1);
00125     col->e_type = CACHE_INSERT (type);
00126     col->hash_of_entities = g_hash_table_new (guid_hash_to_guint, id_compare);
00127     col->data = NULL;
00128     return col;
00129 }

void qof_collection_set_data ( QofCollection col,
gpointer  user_data 
)

Retrieve arbitrary object-defined data

Definition at line 365 of file qofid.c.

00366 {
00367     if (col)
00368     {
00369         col->data = user_data;
00370     }
00371 }

const GUID* qof_entity_get_guid ( QofEntity  ) 

Return the GUID of this entity

Definition at line 105 of file qofid.c.

00106 {
00107     if (!ent)
00108         return guid_null ();
00109     return &ent->guid;
00110 }

void qof_entity_init ( QofEntity ,
QofIdType  ,
QofCollection  
)

Initialise the memory associated with an entity

Definition at line 49 of file qofid.c.

00050 {
00051     g_return_if_fail (NULL != tab);
00052 
00053     /* XXX We passed redundant info to this routine ... but I think that's
00054      * OK, it might eliminate programming errors. */
00055     if (safe_strcmp (tab->e_type, type))
00056     {
00057         PERR ("attempt to insert \"%s\" into \"%s\"", type, tab->e_type);
00058         return;
00059     }
00060     ent->e_type = CACHE_INSERT (type);
00061 
00062     do
00063     {
00064         guid_new (&ent->guid);
00065 
00066         if (NULL == qof_collection_lookup_entity (tab, &ent->guid))
00067             break;
00068 
00069         PWARN ("duplicate id created, trying again");
00070     }
00071     while (1);
00072 
00073     ent->collection = tab;
00074 
00075     qof_collection_insert_entity (tab, ent);
00076 }

void qof_entity_release ( QofEntity  ) 

Release the data associated with this entity. Dont actually free the memory associated with the instance.

Definition at line 79 of file qofid.c.

00080 {
00081     if (!ent->collection)
00082         return;
00083     qof_collection_remove_entity (ent);
00084     CACHE_REMOVE (ent->e_type);
00085     ent->e_type = NULL;
00086 }


Generated on Sat Aug 15 15:46:32 2009 for QOF by  doxygen 1.5.9