MgQuery

MgQuery — Represents any kind of DML query

Synopsis




            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);
const gchar* mg_query_get_query_type_string (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);
gboolean    mg_query_is_equal_to            (MgQuery *query,
                                             MgQuery *compare_to);
MgQfield*   mg_query_get_field_by_sql_naming
                                            (MgQuery *query,
                                             const gchar *sql_naming);
GSList*     mg_query_get_fields_by_target   (MgQuery *query,
                                             MgTarget *target,
                                             gboolean visible_fields_only);
MgQfield*   mg_query_get_visible_field_by_ref_field
                                            (MgQuery *query,
                                             MgTarget *target,
                                             MgField *ref_field);
MgQfield*   mg_query_get_any_field_by_ref_field
                                            (MgQuery *query,
                                             MgTarget *target,
                                             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);
gboolean    mg_query_add_target             (MgQuery *query,
                                             MgTarget *target,
                                             GError **error);
void        mg_query_del_target             (MgQuery *query,
                                             MgTarget *target);
GSList*     mg_query_get_targets            (MgQuery *query);
MgTarget*   mg_query_get_target_by_xml_id   (MgQuery *query,
                                             const gchar *xml_id);
MgTarget*   mg_query_get_target_by_alias    (MgQuery *query,
                                             const gchar *alias_or_name);
GSList*     mg_query_get_target_pkfields    (MgQuery *query,
                                             MgTarget *target);
GSList*     mg_query_get_joins              (MgQuery *query);
MgJoin*     mg_query_get_join_by_targets    (MgQuery *query,
                                             MgTarget *target1,
                                             MgTarget *target2);
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);
GSList*     mg_query_expand_all_field       (MgQuery *query,
                                             MgTarget *target);
void        mg_query_order_fields_using_join_conds
                                            (MgQuery *query);

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

MgQuery

typedef struct _MgQuery 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_UNIONUnion of SELECT queries
MG_QUERY_TYPE_INTERSECTIntersection of SELECT queries
MG_QUERY_TYPE_EXCEPTA 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.

The error is set only if the SQL statement parsing produced an error; there is always a new MgQuery object which is returned.

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_get_query_type_string ()

const gchar* mg_query_get_query_type_string (MgQuery *query);

Get the type of a query as a human readable string

query : a MgQuery object
Returns : a string for 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_is_equal_to ()

gboolean    mg_query_is_equal_to            (MgQuery *query,
                                             MgQuery *compare_to);

Compares query and compare_to from the point of view of the result of the execution of the two queries.

query : a MgQuery object
compare_to : a MgQuery object
Returns : TRUE is query and compare_to represent the same query

mg_query_get_field_by_sql_naming ()

MgQfield*   mg_query_get_field_by_sql_naming
                                            (MgQuery *query,
                                             const gchar *sql_naming);

query : a MgQuery object
sql_naming :
Returns :

mg_query_get_fields_by_target ()

GSList*     mg_query_get_fields_by_target   (MgQuery *query,
                                             MgTarget *target,
                                             gboolean visible_fields_only);

Get a list of all the MgQfield objects in query which depent on the existance of target.

query : a MgQuery object
target : a MgTarget object representing a target in query
visible_fields_only :
Returns : a new list of MgQfield objects

mg_query_get_visible_field_by_ref_field ()

MgQfield*   mg_query_get_visible_field_by_ref_field
                                            (MgQuery *query,
                                             MgTarget *target,
                                             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.

If target is specified, then the returned field will be linked to that MgTarget object.

query : a MgQuery object
target : a MgTarget, or NULL
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,
                                             MgTarget *target,
                                             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.

If target is specified, then the returned field will be linked to that MgTarget object.

query : a MgQuery object
target : a MgTarget, or NULL
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 : the new string

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.

query : a MgQuery object
Returns : the list of MgQuery objects

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_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 occurred

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_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_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_by_alias ()

MgTarget*   mg_query_get_target_by_alias    (MgQuery *query,
                                             const gchar *alias_or_name);

Get a pointer to a MgTarget (which must be within query) using its alias (if not found then alias_or_name is interpreted as the target name)

query : a MgQuery object
alias_or_name : the alias or name
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_get_join_by_targets ()

MgJoin*     mg_query_get_join_by_targets    (MgQuery *query,
                                             MgTarget *target1,
                                             MgTarget *target2);

Find a join in query which joins the target1 and target2 targets

query : a MgQuery object
target1 : a MgTarget object
target2 : a MgTarget object
Returns : the MgJoin object, or NULL

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

mg_query_expand_all_field ()

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

Converts each visible "target.*" (MgQfAll) field into its list of fields. For example "t1.*" becomes "t1.a, t1.b" if table t1 is composed of fields "a" and "b". The original MgQfAll field is not removed, but simply rendered non visible.

The returned list must be free'd by the caller using g_slist_free().

query : a MgQuery object
target : a MgTarget, or NULL
Returns : a new list of the MgQfield objects which have been created

mg_query_order_fields_using_join_conds ()

void        mg_query_order_fields_using_join_conds
                                            (MgQuery *query);

Re-orders the fields in query using the joins' conditions: for each join condition, the used query fields are grouped together near the 1st visible field.

query : a MgQuery object

Properties

The "cond-serial" property

  "cond-serial"          guint                 : Read

Allowed values: >= 1

Default value: 1


The "field-serial" property

  "field-serial"         guint                 : Read

Allowed values: >= 1

Default value: 1


The "really-all-fields" property

  "really-all-fields"    gpointer              : Read


The "target-serial" property

  "target-serial"        guint                 : Read

Allowed values: >= 1

Default value: 1

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.