MgQuery

Name

MgQuery -- Represents any kind of DML query

Synopsis



#define     MG_QUERY_TYPE
#define     MG_QUERY                        (obj)
#define     IS_MG_QUERY                     (obj)
#define     MG_QUERY_CLASS                  (klass)
struct      MgQuery;
enum        MgQueryType;
guint       mg_query_get_type               (void);
GObject*    mg_query_new                    (MgConf *conf);
GObject*    mg_query_new_from_sql           (MgConf *conf,
                                             const gchar *sql,
                                             GError **error);
GObject*    mg_query_new_copy               (MgQuery *orig,
                                             GHashTable *replacements);
void        mg_query_set_query_type         (MgQuery *query,
                                             MgQueryType type);
MgQueryType mg_query_get_query_type         (MgQuery *query);
gboolean    mg_query_is_select_query        (MgQuery *query);
gboolean    mg_query_is_modif_query         (MgQuery *query);
MgQuery*    mg_query_get_parent_query       (MgQuery *query);
MgQfield*   mg_query_get_visible_field_by_ref_field
                                            (MgQuery *query,
                                             MgField *ref_field);
MgQfield*   mg_query_get_any_field_by_ref_field
                                            (MgQuery *query,
                                             MgField *ref_field);
void        mg_query_set_sql_text           (MgQuery *query,
                                             const gchar *sql,
                                             GError **error);
const gchar* mg_query_get_sql_text          (MgQuery *query);
GSList*     mg_query_get_sub_queries        (MgQuery *query);
void        mg_query_add_sub_query          (MgQuery *query,
                                             MgQuery *sub_query);
void        mg_query_del_sub_query          (MgQuery *query,
                                             MgQuery *sub_query);
const GSList* mg_query_get_param_sources    (MgQuery *query);
void        mg_query_add_param_source       (MgQuery *query,
                                             MgQuery *param_source);
void        mg_query_del_param_source       (MgQuery *query,
                                             MgQuery *param_source);
GSList*     mg_query_get_targets            (MgQuery *query);
gboolean    mg_query_add_target             (MgQuery *query,
                                             MgTarget *target,
                                             GError **error);
void        mg_query_del_target             (MgQuery *query,
                                             MgTarget *target);
MgTarget*   mg_query_get_target_by_xml_id   (MgQuery *query,
                                             const gchar *xml_id);
GSList*     mg_query_get_target_pkfields    (MgQuery *query,
                                             MgTarget *target);
GSList*     mg_query_get_joins              (MgQuery *query);
gboolean    mg_query_add_join               (MgQuery *query,
                                             MgJoin *join);
void        mg_query_del_join               (MgQuery *query,
                                             MgJoin *join);
void        mg_query_set_condition          (MgQuery *query,
                                             MgCondition *cond);
MgCondition* mg_query_get_condition         (MgQuery *query);
GSList*     mg_query_get_main_conditions    (MgQuery *query);
void        mg_query_set_order_by_field     (MgQuery *query,
                                             MgQfield *field,
                                             gint order,
                                             gboolean ascendant);
gint        mg_query_get_order_by_field     (MgQuery *query,
                                             MgQfield *field,
                                             gboolean *ascendant);

Object Hierarchy


  GObject
   +----MgBase
         +----MgQuery

Implemented Interfaces

MgQuery implements MgXmlStorage, MgRenderer, MgReferer and MgEntity.

Properties


  "cond-serial"          guint                : Read
  "field-serial"         guint                : Read
  "really-all-fields"    gpointer             : Read
  "target-serial"        guint                : Read

Signal Prototypes


"condition-changed"
            void        user_function      (MgQuery *mgquery,
                                            gpointer user_data);
"join-added"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"join-removed"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"join-updated"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"sub-query-added"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"sub-query-removed"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"sub-query-updated"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"target-added"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"target-removed"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"target-updated"
            void        user_function      (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);
"type-changed"
            void        user_function      (MgQuery *mgquery,
                                            gpointer user_data);

Description

Any query (which can be of any type, see the MgQueryType enum) can be represented by a MgQuery object. Also a query may require some parameters to be provided before in can be executed; each parameter is then represented by a MgParameter object, and parameters required for a query are organised within a MgContext object.

It implements the MgEntity, MgXmlStorage, MgReferer and MgRenderer interfaces.

Details

MG_QUERY_TYPE

#define MG_QUERY_TYPE          (mg_query_get_type())


MG_QUERY()

#define MG_QUERY(obj)          G_TYPE_CHECK_INSTANCE_CAST (obj, mg_query_get_type(), MgQuery)

obj :


IS_MG_QUERY()

#define IS_MG_QUERY(obj)       G_TYPE_CHECK_INSTANCE_TYPE (obj, mg_query_get_type ())

obj :


MG_QUERY_CLASS()

#define MG_QUERY_CLASS(klass)  G_TYPE_CHECK_CLASS_CAST (klass, mg_query_get_type (), MgQueryClass)

klass :


struct MgQuery

struct MgQuery;


enum MgQueryType

typedef enum {
        MG_QUERY_TYPE_SELECT,
	MG_QUERY_TYPE_INSERT,
	MG_QUERY_TYPE_UPDATE,
	MG_QUERY_TYPE_DELETE,
        MG_QUERY_TYPE_UNION,
        MG_QUERY_TYPE_INTERSECT,
	MG_QUERY_TYPE_EXCEPT,
        MG_QUERY_TYPE_NON_PARSED_SQL
} MgQueryType;

MG_QUERY_TYPE_SELECT

MG_QUERY_TYPE_INSERT

MG_QUERY_TYPE_UPDATE

MG_QUERY_TYPE_DELETE

MG_QUERY_TYPE_UNION

Union of SELECT queries

MG_QUERY_TYPE_INTERSECT

Intersection of SELECT queries

MG_QUERY_TYPE_EXCEPT

A SELECT query minus another SELECT query

MG_QUERY_TYPE_NON_PARSED_SQL


mg_query_get_type ()

guint       mg_query_get_type               (void);

Returns :


mg_query_new ()

GObject*    mg_query_new                    (MgConf *conf);

Creates a new MgQuery object

conf :

a MgConf object

Returns :

the new object


mg_query_new_from_sql ()

GObject*    mg_query_new_from_sql           (MgConf *conf,
                                             const gchar *sql,
                                             GError **error);

Creates a new MgQuery object and fills its structure by parsing the sql. If the parsing failed, then the returned query is of type MG_QUERY_TYPE_NON_PARSED_SQL.

To be parsed successfully, the expected SQL must respect the SQL standard; some extensions have been added to be able to define variables within the SQL statement. See the introduction to the MgQuery for more information.

conf :

a MgConf object

sql :

an SQL statement

error :

location to store error, or NULL

Returns :

a new MgQuery


mg_query_new_copy ()

GObject*    mg_query_new_copy               (MgQuery *orig,
                                             GHashTable *replacements);

Copy constructor

orig :

a MgQuery to make a copy of

replacements :

a hash table to store replacements, or NULL

Returns :

a the new copy of orig


mg_query_set_query_type ()

void        mg_query_set_query_type         (MgQuery *query,
                                             MgQueryType type);

Sets the type of query

query :

a MgQuery object

type :

the new type of query


mg_query_get_query_type ()

MgQueryType mg_query_get_query_type         (MgQuery *query);

Get the type of a query

query :

a MgQuery object

Returns :

the type of query


mg_query_is_select_query ()

gboolean    mg_query_is_select_query        (MgQuery *query);

Tells if query is a SELECTION query (a simple SELECT, UNION, INTERSECT or EXCEPT); pure SQL queries are not handled and will always return FALSE.

query :

a # MgQuery object

Returns :

TRUE if query is a selection query


mg_query_is_modif_query ()

gboolean    mg_query_is_modif_query         (MgQuery *query);

Tells if query is a modification query (a simple UPDATE, DELETE, INSERT).; pure SQL queries are not handled and will always return FALSE.

query :

a # MgQuery object

Returns :

TRUE if query is a modification query


mg_query_get_parent_query ()

MgQuery*    mg_query_get_parent_query       (MgQuery *query);

Get the parent query of query

query :

a MgQuery object

Returns :

the parent query, or NULL if query does not have any parent


mg_query_get_visible_field_by_ref_field ()

MgQfield*   mg_query_get_visible_field_by_ref_field
                                            (MgQuery *query,
                                             MgField *ref_field);

Finds the first visible MgQfield object in query which represents ref_field. The returned object will be a MgQfField object which represents ref_field.

query :

a MgQuery object

ref_field :

a MgField object

Returns :

a MgQfField object or NULL


mg_query_get_any_field_by_ref_field ()

MgQfield*   mg_query_get_any_field_by_ref_field
                                            (MgQuery *query,
                                             MgField *ref_field);

Finds the first (visible or not) MgQfField object in query which represents ref_field. The returned object will be a MgQfField object which represents ref_field.

query :

a MgQuery object

ref_field :

a MgField object

Returns :

a MgQfField object or NULL


mg_query_set_sql_text ()

void        mg_query_set_sql_text           (MgQuery *query,
                                             const gchar *sql,
                                             GError **error);

Defines query's contents from an SQL statement. The SQL text is parsed and the internal query structured is built from that; the query type is also set. If the SQL text cannot be parsed, then the internal structure of the query is emptied and the query type is set to MG_QUERY_TYPE_NON_PARSED_SQL.

To be parsed successfully, the expected SQL must respect the SQL standard; some extensions have been added to be able to define variables within the SQL statement. See the introduction to the MgQuery for more information.

query :

a # MgQuery object

sql :

the SQL statement

error :

location to store parsing error, or NULL


mg_query_get_sql_text ()

const gchar* mg_query_get_sql_text          (MgQuery *query);

Obtain a new string representing the SQL version of the query.

WARNING: the returned SQL statement may contain some extensions which allow for the definition of variables (see the introduction to the MgQuery for more information). As such the returned SQL cannot be executed as it may provoque errors. To get an executable statement, use the MgRenderer interface's methods.

query :

a # MgQuery object

Returns :


mg_query_get_sub_queries ()

GSList*     mg_query_get_sub_queries        (MgQuery *query);

Get a list of all the sub-queries managed by query

query :

a MgQuery object

Returns :

a new list of the sub-queries


mg_query_add_sub_query ()

void        mg_query_add_sub_query          (MgQuery *query,
                                             MgQuery *sub_query);

Add sub_query to query. Sub queries are managed by their parent query, and as such they are destroyed when their parent query is destroyed.

query :

a MgQuery object

sub_query :

a MgQuery object


mg_query_del_sub_query ()

void        mg_query_del_sub_query          (MgQuery *query,
                                             MgQuery *sub_query);

Removes sub_query from query. sub_query MUST be present within query.

query :

a MgQuery object

sub_query :

a MgQuery object


mg_query_get_param_sources ()

const GSList* mg_query_get_param_sources    (MgQuery *query);

Get a list of the parameter source queries that are references as such by query.

Return: the list of MgQuery objects

query :

a MgQuery object

Returns :


mg_query_add_param_source ()

void        mg_query_add_param_source       (MgQuery *query,
                                             MgQuery *param_source);

Tells query that param_source is a query which potentially will constraint the possible values of one or more of query's parameters. This implies that query keeps a reference on param_source.

query :

a MgQuery object

param_source :

a MgQuery object


mg_query_del_param_source ()

void        mg_query_del_param_source       (MgQuery *query,
                                             MgQuery *param_source);

Tells query that it should no longer take care of param_source. The parameters which depend on param_source will still depend on it, though.

query :

a MgQuery object

param_source :

a MgQuery object


mg_query_get_targets ()

GSList*     mg_query_get_targets            (MgQuery *query);

Get a list of all the targets used in query

query :

a MgQuery object

Returns :

a new list of the targets


mg_query_add_target ()

gboolean    mg_query_add_target             (MgQuery *query,
                                             MgTarget *target,
                                             GError **error);

Adds a target to query. A target represents a entity (it can actually be a table, a view, or another query) which query will use.

For a SELECT query, the targets appear after the FROM clause. The targets can be joined two by two using MgJoin objects

For UPDATE, DELETE or INSERT queries, there can be only ONE MgTarget object which is the one where the data modifications are performed.

For UNION and INTERSECT queries, there is no possible MgTarget object.

query :

a MgQuery object

target :

a MgTarget to add to query

error :

location to store error, or NULL

Returns :

TRUE if no error occured


mg_query_del_target ()

void        mg_query_del_target             (MgQuery *query,
                                             MgTarget *target);

Removes target from query. target MUST be present within query. Warning: All the joins and fields which depended on target are also removed.

query :

a MgQuery object

target :

a MgTarget object


mg_query_get_target_by_xml_id ()

MgTarget*   mg_query_get_target_by_xml_id   (MgQuery *query,
                                             const gchar *xml_id);

Get a pointer to a MgTarget (which must be within query) using its XML Id

query :

a MgQuery object

xml_id :

the XML Id of the requested MgTarget object

Returns :

the MgTarget object, or NULL if not found


mg_query_get_target_pkfields ()

GSList*     mg_query_get_target_pkfields    (MgQuery *query,
                                             MgTarget *target);

Makes a list of the MgQfield objects which represent primary key fields of the entity represented by target.

If the entity represented by target does not have any primary key, or if the primary key's fields are not present in query, then the returned value is NULL.

query :

a MgQuery object

target :

a MgTarget object

Returns :

a new GSList, or NULL.


mg_query_get_joins ()

GSList*     mg_query_get_joins              (MgQuery *query);

Get a list of all the joins used in query

query :

a MgQuery object

Returns :

a new list of the joins


mg_query_add_join ()

gboolean    mg_query_add_join               (MgQuery *query,
                                             MgJoin *join);

Add a join to query. A join is defined by the two MgTarget objects it joins and by a join condition which MUST ONLY make use of fields of the two entities represented by the targets.

For any given couple of MgTarget objects, there can exist ONLY ONE MgJoin which joins the two.

query :

a MgQuery object

join :

a MgJoin object

Returns :

TRUE on success, and FALSE otherwise


mg_query_del_join ()

void        mg_query_del_join               (MgQuery *query,
                                             MgJoin *join);

Removes join from query. join MUST be present within query.

query :

a MgQuery object

join :

a MgJoin object


mg_query_set_condition ()

void        mg_query_set_condition          (MgQuery *query,
                                             MgCondition *cond);

Sets the query's associated condition

query :

a MgQuery object

cond :

a MgCondition object


mg_query_get_condition ()

MgCondition* mg_query_get_condition         (MgQuery *query);

Get the query's associated condition

query :

a MgQuery object

Returns :

the MgCondition object


mg_query_get_main_conditions ()

GSList*     mg_query_get_main_conditions    (MgQuery *query);

Makes a list of all the conditions (part of the WHERE clause) which are always verified by query when it is executed.

Examples: if the WHERE clause is: --> "A and B" then the list will contains {A, B} --> "A and (B or C)" it will contain {A, B or C} --> "A and (B and not C)", it will contain {A, B, not C}

query :

a MgQuery object

Returns :

a new list of MgCondition objects


mg_query_set_order_by_field ()

void        mg_query_set_order_by_field     (MgQuery *query,
                                             MgQfield *field,
                                             gint order,
                                             gboolean ascendant);

Sets field to be used in the ORDER BY clause (using the order and ascendant attributes) if order >= 0. If order < 0, then field will not be used in the ORDER BY clause.

query :

a MgQuery

field :

a MgQfield which is in query

order :

the order in the list of ORDER BY fields (starts at 0), or -1

ascendant :

TRUE to sort ascending


mg_query_get_order_by_field ()

gint        mg_query_get_order_by_field     (MgQuery *query,
                                             MgQfield *field,
                                             gboolean *ascendant);

Tells if field (which MUST be in query) is part of the ORDER BY clause.

query :

a MgQuery

field :

a MgQfield which is in query

ascendant :

if not NULL, will be set TRUE if ascendant sorting and FALSE otherwise

Returns :

-1 if no, and the order where it appears in the ORDER BY list otherwise

Properties

"cond-serial" (guint : Read)

"field-serial" (guint : Read)

"really-all-fields" (gpointer : Read)

"target-serial" (guint : Read)

Signals

The "condition-changed" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer user_data);

mgquery :

the object which received the signal.

user_data :

user data set when the signal handler was connected.


The "join-added" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "join-removed" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "join-updated" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "sub-query-added" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "sub-query-removed" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "sub-query-updated" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "target-added" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "target-removed" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "target-updated" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer arg1,
                                            gpointer user_data);

mgquery :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.


The "type-changed" signal

void        user_function                  (MgQuery *mgquery,
                                            gpointer user_data);

mgquery :

the object which received the signal.

user_data :

user data set when the signal handler was connected.