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GNOME Data Access 4 manual | ![]() |
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Top | Description | Object Hierarchy | Properties |
GdaMetaStruct; enum GdaMetaStructFeature; enum GdaMetaStructError; enum GdaMetaDbObjectType; GdaMetaDbObject; #define GDA_META_DB_OBJECT (dbo) #define GDA_META_TABLE (dbobj) #define GDA_META_VIEW (dbobj) GdaMetaTable; GdaMetaView; GdaMetaTableColumn; #define GDA_META_TABLE_COLUMN (col) const GValue * gda_meta_table_column_get_attribute (GdaMetaTableColumn *tcol
,const gchar *attribute
); void gda_meta_table_column_set_attribute (GdaMetaTableColumn *tcol
,const gchar *attribute
,const GValue *value
,GDestroyNotify destroy
); #define gda_meta_table_column_set_attribute_static(column, attribute, value) void gda_meta_table_column_foreach_attribute (GdaMetaTableColumn *tcol
,GdaAttributesManagerFunc func
,gpointer data
); enum GdaMetaForeignKeyPolicy; GdaMetaTableForeignKey; #define GDA_META_TABLE_FOREIGN_KEY (fk) #define GDA_META_TABLE_FOREIGN_KEY_ON_UPDATE_POLICY(fk) #define GDA_META_TABLE_FOREIGN_KEY_ON_DELETE_POLICY(fk) #define GDA_META_TABLE_FOREIGN_KEY_IS_DECLARED(fk) #define GDA_META_STRUCT_ERROR GdaMetaStruct * gda_meta_struct_new (GdaMetaStore *store
,GdaMetaStructFeature features
); GdaMetaDbObject * gda_meta_struct_complement (GdaMetaStruct *mstruct
,GdaMetaDbObjectType type
,const GValue *catalog
,const GValue *schema
,const GValue *name
,GError **error
); gboolean gda_meta_struct_complement_schema (GdaMetaStruct *mstruct
,const GValue *catalog
,const GValue *schema
,GError **error
); gboolean gda_meta_struct_complement_default (GdaMetaStruct *mstruct
,GError **error
); gboolean gda_meta_struct_complement_all (GdaMetaStruct *mstruct
,GError **error
); gboolean gda_meta_struct_complement_depend (GdaMetaStruct *mstruct
,GdaMetaDbObject *dbo
,GError **error
); enum GdaMetaSortType; gboolean gda_meta_struct_sort_db_objects (GdaMetaStruct *mstruct
,GdaMetaSortType sort_type
,GError **error
); GSList * gda_meta_struct_get_all_db_objects (GdaMetaStruct *mstruct
); GdaMetaDbObject * gda_meta_struct_get_db_object (GdaMetaStruct *mstruct
,const GValue *catalog
,const GValue *schema
,const GValue *name
); GdaMetaTableColumn * gda_meta_struct_get_table_column (GdaMetaStruct *mstruct
,GdaMetaTable *table
,const GValue *col_name
); enum GdaMetaGraphInfo; gchar * gda_meta_struct_dump_as_graph (GdaMetaStruct *mstruct
,GdaMetaGraphInfo info
,GError **error
);
"features" guint : Read / Write / Construct Only "meta-store" GdaMetaStore* : Read / Write / Construct Only
The GdaMetaStruct object reads data from a GdaMetaStore object and creates an easy to use in memory representation for some database objects. For example one can easily analyze the columns of a table (or its foreign keys) using a GdaMetaStruct.
When created, the new GdaMetaStruct object is empty (it does not have any information about any database object).
Information about database objects is computed upon request using the gda_meta_struct_complement()
method. Information
about individual database objects is represented by GdaMetaDbObject structures, which can be obtained using
gda_meta_struct_get_db_object()
or gda_meta_struct_get_all_db_objects()
.
Note that the GdaMetaDbObject structures may change or may be removed or replaced by others, so it not
advised to keep pointers to these structures: pointers to these structures should be considered valid
as long as gda_meta_struct_complement()
and other similar functions have not been called.
In the following code sample, one prints the columns names and types of a table:
GdaMetaStruct *mstruct; GdaMetaDbObject *dbo; GValue *catalog, *schema, *name; /* Define name (and optionnally catalog and schema) */ [...] mstruct = gda_meta_struct_new (); gda_meta_struct_complement (mstruct, store, GDA_META_DB_TABLE, catalog, schema, name, NULL); dbo = gda_meta_struct_get_db_object (mstruct, catalog, schema, name); if (!dbo) g_print ("Table not found\n"); else { GSList *list; for (list = GDA_META_TABLE (dbo)->columns; list; list = list->next) { GdaMetaTableColumn *tcol = GDA_META_TABLE_COLUMN (list->data); g_print ("COLUMN: %s (%s)\n", tcol->column_name, tcol->column_type); } } gda_meta_struct_free (mstruct);
If now the database object type is not known, one can use the following code:
GdaMetaStruct *mstruct; GdaMetaDbObject *dbo; GValue *catalog, *schema, *name; /* Define name (and optionnally catalog and schema) */ [...] mstruct = gda_meta_struct_new (); gda_meta_struct_complement (mstruct, store, GDA_META_DB_UNKNOWN, catalog, schema, name, NULL); dbo = gda_meta_struct_get_db_object (mstruct, catalog, schema, name); if (!dbo) g_print ("Object not found\n"); else { if ((dbo->obj_type == GDA_META_DB_TABLE) || (dbo->obj_type == GDA_META_DB_VIEW)) { if (dbo->obj_type == GDA_META_DB_TABLE) g_print ("Is a table\n"); else if (dbo->obj_type == GDA_META_DB_VIEW) { g_print ("Is a view, definition is:\n"); g_print ("%s\n", GDA_META_VIEW (dbo)->view_def); } GSList *list; for (list = GDA_META_TABLE (dbo)->columns; list; list = list->next) { GdaMetaTableColumn *tcol = GDA_META_TABLE_COLUMN (list->data); g_print ("COLUMN: %s (%s)\n", tcol->column_name, tcol->column_type); } } else g_print ("Not a table or a view\n"); } gda_meta_struct_free (mstruct);
typedef enum { GDA_META_STRUCT_FEATURE_NONE = 0, GDA_META_STRUCT_FEATURE_FOREIGN_KEYS = 1 << 0, GDA_META_STRUCT_FEATURE_VIEW_DEPENDENCIES = 1 << 1, GDA_META_STRUCT_FEATURE_ALL = GDA_META_STRUCT_FEATURE_FOREIGN_KEYS | GDA_META_STRUCT_FEATURE_VIEW_DEPENDENCIES } GdaMetaStructFeature;
Controls which features are computed about database objects.
typedef enum { GDA_META_STRUCT_UNKNOWN_OBJECT_ERROR, GDA_META_STRUCT_DUPLICATE_OBJECT_ERROR, GDA_META_STRUCT_INCOHERENCE_ERROR, GDA_META_STRUCT_XML_ERROR } GdaMetaStructError;
typedef enum { GDA_META_DB_UNKNOWN, GDA_META_DB_TABLE, GDA_META_DB_VIEW } GdaMetaDbObjectType;
Type of database object which can be handled as a GdaMetaDbObject
typedef struct { union { GdaMetaTable meta_table; GdaMetaView meta_view; } extra; GdaMetaDbObjectType obj_type; gboolean outdated; gchar *obj_catalog; gchar *obj_schema; gchar *obj_name; gchar *obj_short_name; gchar *obj_full_name; gchar *obj_owner; GSList *depend_list; } GdaMetaDbObject;
Struture to hold information about each database object (tables, views, ...), its contents must not be modified.
Note: obj_catalog
, obj_schema
, obj_name
, obj_short_name
and obj_full_name
respect the
SQL identifiers convention used in
GdaMetaStore objects. Before using these SQL identifiers, you should check the
gda_sql_identifier_quote()
to know if is it is necessary to surround by double quotes
before using in an SQL statement.
GdaMetaDbObjectType |
the type of object (table, view) |
set to TRUE if the information in this GdaMetaDbObject may be outdated because the GdaMetaStore has been updated |
|
the catalog the object is in | |
the schema the object is in | |
the object's name | |
the shortest way to name the object | |
the full name of the object (in the <schema>.<nameagt; notation | |
object's owner | |
list of GdaMetaDbObject pointers on which this object depends (through foreign keys or tables used for views). [element-type Gda.MetaDbObject] |
#define GDA_META_DB_OBJECT(dbo) ((GdaMetaDbObject*)(dbo))
Casts dbo
to a GdaMetaDbObject, no check is made on the validity of dbo
|
a pointer |
Returns : |
a pointer to a GdaMetaDbObject |
#define GDA_META_TABLE(dbobj) (&((dbobj)->extra.meta_table))
Casts dbo
to a GdaMetaTable, no check is made on the validity of dbo
Returns : |
a pointer to a GdaMetaTable |
#define GDA_META_VIEW(dbobj) (&((dbobj)->extra.meta_view))
Casts dbo
to a GdaMetaView, no check is made on the validity of dbo
Returns : |
a pointer to a GdaMetaView |
typedef struct { GSList *columns; /* PK fields index */ gint *pk_cols_array; gint pk_cols_nb; /* Foreign keys */ GSList *reverse_fk_list; /* list of GdaMetaTableForeignKey where @depend_on == this GdaMetaDbObject */ GSList *fk_list; /* list of GdaMetaTableForeignKey where @meta_table == this GdaMetaDbObject */ } GdaMetaTable;
This structure specifies a GdaMetaDbObject to represent a table's specific attributes, its contents must not be modified.
Note that in some cases, the columns cannot be determined for views, and in this case the
columns
will be NULL
(this can be the case for example with SQLite where a view
uses a function which is not natively provided by SQLite.
list of GdaMetaTableColumn structures, one for each column in the table. [element-type Gda.MetaTableColumn] | |
index of the columns part of the primary key for the table (WARNING: columns numbering here start at 0) | |
size of the pk_cols_array array |
|
list of GdaMetaTableForeignKey where the referenced table is this table. [element-type Gda.MetaTableForeignKey] | |
list of GdaMetaTableForeignKey for this table. [element-type Gda.MetaTableForeignKey] |
typedef struct { GdaMetaTable table; gchar *view_def; gboolean is_updatable; } GdaMetaView;
This structure specifies a GdaMetaDbObject to represent a view's specific attributes, its contents must not be modified.
GdaMetaTable |
a view is also a table as it has columns |
views' definition | |
tells if the view's contents can be updated |
typedef struct { gchar *column_name; gchar *column_type; GType gtype; gboolean pkey; gboolean nullok; gchar *default_value; } GdaMetaTableColumn;
This structure represents a table of view's column, its contents must not be modified.
the column's name | |
the column's DBMS's type | |
the detected column's GType | |
tells if the column is part of a primary key | |
tells if the column can be NULL
|
|
the column's default value, represented as a valid SQL value (surrounded by simple quotes for strings, ...), or NULL if column has no default value. [allow-none]
|
#define GDA_META_TABLE_COLUMN(col) ((GdaMetaTableColumn*)(col))
Casts col
to a GdaMetaTableColumn, no check is made
|
a pointer |
Returns : |
col , casted to a GdaMetaTableColumn
|
const GValue * gda_meta_table_column_get_attribute (GdaMetaTableColumn *tcol
,const gchar *attribute
);
Get the value associated to a named attribute.
Attributes can have any name, but Libgda proposes some default names, see this section.
|
a GdaMetaTableColumn |
|
attribute name as a string |
Returns : |
a read-only GValue, or NULL if not attribute named attribute has been set for column . [transfer none]
|
void gda_meta_table_column_set_attribute (GdaMetaTableColumn *tcol
,const gchar *attribute
,const GValue *value
,GDestroyNotify destroy
);
Set the value associated to a named attribute.
Attributes can have any name, but Libgda proposes some default names, see this section.
If there is already an attribute named attribute
set, then its value is replaced with the new value
,
except if value
is NULL
, in which case the attribute is removed.
Warning: attribute
is not copied, if it needs to be freed when not used anymore, then destroy
should point to
the functions which will free it (typically g_free()
). If attribute
does not need to be freed, then destroy
can be NULL
.
|
a GdaMetaTableColumn |
|
attribute name as a static string |
|
a GValue, or NULL . [allow-none]
|
|
function called when attribute has to be freed, or NULL . [allow-none]
|
#define gda_meta_table_column_set_attribute_static(column,attribute,value) gda_meta_table_column_set_attribute((column),(attribute),(value),NULL)
This function is similar to gda_meta_table_column_set_attribute()
but for static strings
|
a GdaMetaTableColumn |
|
attribute's name |
|
a GValue, or NULL . [allow-none]
|
void gda_meta_table_column_foreach_attribute (GdaMetaTableColumn *tcol
,GdaAttributesManagerFunc func
,gpointer data
);
Calls func
for each attribute set to tcol
|
a GdaMetaTableColumn |
|
a GdaAttributesManagerFunc function. [scope call] |
|
user data to be passed as last argument of func each time it is called. [closure]
|
typedef enum { GDA_META_FOREIGN_KEY_UNKNOWN, GDA_META_FOREIGN_KEY_NONE, GDA_META_FOREIGN_KEY_NO_ACTION, GDA_META_FOREIGN_KEY_RESTRICT, GDA_META_FOREIGN_KEY_CASCADE, GDA_META_FOREIGN_KEY_SET_NULL, GDA_META_FOREIGN_KEY_SET_DEFAULT } GdaMetaForeignKeyPolicy;
Defines the filtering policy of a foreign key when invoked on an UPDATE or DELETE operation.
unspecified policy | |
not enforced policy | |
return an error, no action taken | |
same as GDA_META_FOREIGN_KEY_NO_ACTION , not deferrable
|
|
policy is to delete any rows referencing the deleted row, or update the value of the referencing column to the new value of the referenced column, respectively | |
policy is to set the referencing column to NULL | |
policy is to set the referencing column to its default value |
typedef struct { GdaMetaDbObject *meta_table; GdaMetaDbObject *depend_on; gint cols_nb; gint *fk_cols_array; /* FK fields index */ gchar **fk_names_array; /* FK fields names */ gint *ref_pk_cols_array; /* Ref PK fields index */ gchar **ref_pk_names_array; /* Ref PK fields names */ gchar *fk_name; } GdaMetaTableForeignKey;
This structure represents a foreign key constraint, its contents must not be modified.
GdaMetaDbObject * |
the GdaMetaDbObject for which this structure represents a foreign key |
GdaMetaDbObject * |
the GdaMetaDbObject which is referenced by the foreign key |
the size of the fk_cols_array , fk_names_array , ref_pk_cols_array and ref_pk_names_array arrays |
|
the columns' indexes in meta_table which participate in the constraint (WARNING: columns numbering
here start at 1) |
|
the columns' names in meta_table which participate in the constraint |
|
the columns' indexes in depend_on which participate in the constraint (WARNING: columns numbering
here start at 1) |
|
the columns' names in depend_on which participate in the constraint |
|
#define GDA_META_TABLE_FOREIGN_KEY(fk) ((GdaMetaTableForeignKey*)(fk))
Casts fk
to a GdaMetaTableForeignKey (no check is actuelly being done on fk
's validity)
|
a pointer |
Returns : |
col , casted to a GdaMetaTableForeignKey
|
#define GDA_META_TABLE_FOREIGN_KEY_ON_UPDATE_POLICY(fk) ((GdaMetaForeignKeyPolicy) GPOINTER_TO_INT ((GdaMetaTableForeignKey*)(fk)->on_update_policy))
Tells the actual policy implemented by fk
when used in the context of an UPDATE.
|
a pointer to a GdaMetaTableForeignKey |
Returns : |
the policy as a GdaMetaForeignKeyPolicy |
#define GDA_META_TABLE_FOREIGN_KEY_ON_DELETE_POLICY(fk) ((GdaMetaForeignKeyPolicy) GPOINTER_TO_INT ((GdaMetaTableForeignKey*)(fk)->on_delete_policy))
Tells the actual policy implemented by fk
when used in the context of a DELETE.
|
a pointer to a GdaMetaTableForeignKey |
Returns : |
the policy as a GdaMetaForeignKeyPolicy |
#define GDA_META_TABLE_FOREIGN_KEY_IS_DECLARED(fk) ((((GdaMetaTableForeignKey*)(fk))->declared) ? TRUE : FALSE)
Tells if fk
is an actual foreign key defined in the database's schema, or if it is an indication which
has been added to help Libgda understand the database schema.
|
a pointer to a GdaMetaTableForeignKey |
Returns : |
TRUE if fk has been declared in the database's meta data and FALSE if fk is an actual foreign key defined in the database's schema |
GdaMetaStruct * gda_meta_struct_new (GdaMetaStore *store
,GdaMetaStructFeature features
);
Creates a new GdaMetaStruct object. The features
specifies the extra features which will also be computed:
the more features, the more time it takes to run. Features such as table's columns, each column's attributes, etc
are not optional and will always be computed.
|
a GdaMetaStore from which the new GdaMetaStruct object will fetch information |
|
the kind of extra information the new GdaMetaStruct object will compute |
Returns : |
the newly created GdaMetaStruct object. [transfer full] |
GdaMetaDbObject * gda_meta_struct_complement (GdaMetaStruct *mstruct
,GdaMetaDbObjectType type
,const GValue *catalog
,const GValue *schema
,const GValue *name
,GError **error
);
Creates a new GdaMetaDbObject structure in mstruct
to represent the database object (of type type
)
which can be uniquely identified as catalog
.schema
.name
.
If catalog
is not NULL
, then schema
should not be NULL
.
If both catalog
and schema
are NULL
, then the database object will be the one which is
"visible" by default (that is which can be accessed only by its short name
name).
If catalog
is NULL
and schema
is not NULL
, then the database object will be the one which
can be accessed by its schema
.name
name.
Important note: catalog
, schema
and name
will be used using the following convention:
be surrounded by double quotes for a case sensitive search
otherwise for case insensitive search
For more information, see the meta data section about SQL identifiers.
|
a GdaMetaStruct object |
|
the type of object to add (which can be GDA_META_DB_UNKNOWN) |
|
the catalog the object belongs to (as a G_TYPE_STRING GValue), or NULL . [allow-none]
|
|
the schema the object belongs to (as a G_TYPE_STRING GValue), or NULL . [allow-none]
|
|
the object's name (as a G_TYPE_STRING GValue), not NULL
|
|
a place to store errors, or NULL . [allow-none]
|
Returns : |
the GdaMetaDbObject corresponding to the database object if no error occurred, or NULL . [transfer none]
|
gboolean gda_meta_struct_complement_schema (GdaMetaStruct *mstruct
,const GValue *catalog
,const GValue *schema
,GError **error
);
This method is similar to gda_meta_struct_complement()
but creates GdaMetaDbObject for all the
database object which are in the schema
schema (and in the catalog
catalog).
If catalog
is NULL
, then any catalog will be used, and
if schema
is NULL
then any schema will be used (if schema
is NULL
then catalog must also be NULL
).
Please refer to gda_meta_struct_complement()
form more information.
|
a GdaMetaStruct object |
|
name of a catalog, or NULL . [allow-none]
|
|
name of a schema, or NULL . [allow-none]
|
|
a place to store errors, or NULL . [allow-none]
|
Returns : |
TRUE if no error occurred |
gboolean gda_meta_struct_complement_default (GdaMetaStruct *mstruct
,GError **error
);
This method is similar to gda_meta_struct_complement()
and gda_meta_struct_complement_all()
but creates GdaMetaDbObject for all the
database object which are usable using only their short name (that is which do not need to be prefixed by
the schema in which they are to be used).
Please refer to gda_meta_struct_complement()
form more information.
|
a GdaMetaStruct object |
|
a place to store errors, or NULL . [allow-none]
|
Returns : |
TRUE if no error occurred |
gboolean gda_meta_struct_complement_all (GdaMetaStruct *mstruct
,GError **error
);
This method is similar to gda_meta_struct_complement()
and gda_meta_struct_complement_default()
but creates GdaMetaDbObject for all the database object.
Please refer to gda_meta_struct_complement()
form more information.
|
a GdaMetaStruct object |
|
a place to store errors, or NULL . [allow-none]
|
Returns : |
TRUE if no error occurred |
gboolean gda_meta_struct_complement_depend (GdaMetaStruct *mstruct
,GdaMetaDbObject *dbo
,GError **error
);
This method is similar to gda_meta_struct_complement()
but creates GdaMetaDbObject for all the dependencies
of dbo
.
Please refer to gda_meta_struct_complement()
form more information.
|
a GdaMetaStruct object |
|
a GdaMetaDbObject part of mstruct
|
|
a place to store errors, or NULL . [allow-none]
|
Returns : |
TRUE if no error occurred |
typedef enum { GDA_META_SORT_ALHAPETICAL, GDA_META_SORT_DEPENDENCIES } GdaMetaSortType;
Types of sorting
gboolean gda_meta_struct_sort_db_objects (GdaMetaStruct *mstruct
,GdaMetaSortType sort_type
,GError **error
);
Reorders the list of database objects within mstruct
in a way specified by sort_type
.
|
a GdaMetaStruct object |
|
the kind of sorting requested |
|
a place to store errors, or NULL . [allow-none]
|
Returns : |
TRUE if no error occurred |
GSList * gda_meta_struct_get_all_db_objects (GdaMetaStruct *mstruct
);
Get a list of all the GdaMetaDbObject structures representing database objects in mstruct
. Note that
no GdaMetaDbObject structure must not be modified.
|
a GdaMetaStruct object |
Returns : |
a new GSList list of pointers to GdaMetaDbObject structures which must be destroyed after usage using g_slist_free() . The individual GdaMetaDbObject must not be modified. [transfer container][element-type Gda.MetaDbObject]
|
GdaMetaDbObject * gda_meta_struct_get_db_object (GdaMetaStruct *mstruct
,const GValue *catalog
,const GValue *schema
,const GValue *name
);
Tries to locate the GdaMetaDbObject structure representing the database object named after
catalog
, schema
and name
.
If one or both of catalog
and schema
are NULL
, and more than one database object matches the name, then
the return value is also NULL
.
|
a GdaMetaStruct object |
|
the catalog the object belongs to (as a G_TYPE_STRING GValue), or NULL . [allow-none]
|
|
the schema the object belongs to (as a G_TYPE_STRING GValue), or NULL . [allow-none]
|
|
the object's name (as a G_TYPE_STRING GValue), not NULL
|
Returns : |
the GdaMetaDbObject or NULL if not found. [transfer none]
|
GdaMetaTableColumn * gda_meta_struct_get_table_column (GdaMetaStruct *mstruct
,GdaMetaTable *table
,const GValue *col_name
);
Tries to find the GdaMetaTableColumn representing the column named col_name
in table
.
|
a GdaMetaStruct object |
|
the GdaMetaTable structure to find the column for |
|
the name of the column to find (as a G_TYPE_STRING GValue) |
Returns : |
the GdaMetaTableColumn or NULL if not found. [transfer none]
|
gchar * gda_meta_struct_dump_as_graph (GdaMetaStruct *mstruct
,GdaMetaGraphInfo info
,GError **error
);
Creates a new graph (in the GraphViz syntax) representation of mstruct
.
|
a GdaMetaStruct object |
|
informs what kind of information to show in the resulting graph |
|
a place to store errors, or NULL . [allow-none]
|
Returns : |
a new string, or NULL if an error occurred. [transfer full]
|
"features"
property "features" guint : Read / Write / Construct Only
Allowed values: <= G_MAXINT
Default value: 3
"meta-store"
property"meta-store" GdaMetaStore* : Read / Write / Construct Only
GdaMetaStore object to fetch information from.