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GNOME Data Access 3.0 manual | ![]() |
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GdaParameter; GdaParameter* gda_parameter_new (GType type); GdaParameter* gda_parameter_new_copy (GdaParameter *orig); GdaParameter* gda_parameter_new_string (const gchar *name, const gchar *str); GdaParameter* gda_parameter_new_boolean (const gchar *name, gboolean value); GType gda_parameter_get_g_type (GdaParameter *param); const GValue* gda_parameter_get_value (GdaParameter *param); gchar* gda_parameter_get_value_str (GdaParameter *param); void gda_parameter_set_value (GdaParameter *param, const GValue *value); gboolean gda_parameter_set_value_str (GdaParameter *param, const gchar *value); void gda_parameter_declare_invalid (GdaParameter *param); gboolean gda_parameter_is_valid (GdaParameter *param); const GValue* gda_parameter_get_default_value (GdaParameter *param); void gda_parameter_set_default_value (GdaParameter *param, const GValue *value); gboolean gda_parameter_get_exists_default_value (GdaParameter *param); void gda_parameter_set_exists_default_value (GdaParameter *param, gboolean default_value_exists); void gda_parameter_set_not_null (GdaParameter *param, gboolean not_null); gboolean gda_parameter_get_not_null (GdaParameter *param); gboolean gda_parameter_restrict_values (GdaParameter *param, GdaDataModel *model, gint col, GError **error); gboolean gda_parameter_has_restrict_values (GdaParameter *param, GdaDataModel **model, gint *col); void gda_parameter_bind_to_param (GdaParameter *param, GdaParameter *bind_to); GdaParameter* gda_parameter_get_bind_param (GdaParameter *param);
"entry-plugin" gchar* : Read / Write "full-bind" GdaParameter* : Read / Write "g-type" gulong : Read / Write / Construct Only "not-null" gboolean : Read / Write "restrict-column" gint : Read / Write "restrict-model" GdaDataModel* : Read / Write "simple-bind" GdaParameter* : Read / Write "use-default-value" gboolean : Read / Write
A GdaParameter object basically is a specification for a value and can convey a value once one has been set.
The GdaParameter object offers other features such as:
keeping a list of objects which "are interested" (mentioned as "users" in the API) in the value placed in the parameter: this feature is usefull when parameters are created by objects and when these objects want to be reminded that the parameter has been created by them at a later time
aliasing (binding) to another parameter: this is an easy way to keep several parameters synchronized. There are two modes: one where parameters A and B will always have the same value and where parameter B will update itself whan A changes to mirror tha change but will be allowed to have its own changes afterwards.
values restrictions: a parameter can be told to choose a value among the values in a colmun in a GdaDataModel (beware that this is a declarative feature only and that no policy is enforced regarding values changes)
GdaParameter* gda_parameter_new (GType type);
Creates a new parameter of type type
|
the GType requested |
Returns : |
a new GdaParameter object |
GdaParameter* gda_parameter_new_copy (GdaParameter *orig);
Copy constructor.
|
a GdaParameter object to copy |
Returns : |
a new GdaParameter object |
GdaParameter* gda_parameter_new_string (const gchar *name, const gchar *str);
Creates a new GdaParameter object of type G_TYPE_STRING
|
the name of the parameter to create |
|
the contents of the parameter to create |
Returns : |
a new GdaParameter object |
GdaParameter* gda_parameter_new_boolean (const gchar *name, gboolean value);
Creates a new GdaParameter object of type G_TYPE_BOOLEAN
|
the name of the parameter to create |
|
the value to give to the new parameter |
Returns : |
a new GdaParameter object |
GType gda_parameter_get_g_type (GdaParameter *param);
Get the requested data type for param
.
|
a GdaParameter object |
Returns : |
the data type |
const GValue* gda_parameter_get_value (GdaParameter *param);
Get the value held into the parameter
|
a GdaParameter object |
Returns : |
the value (a NULL value returns a GDA_TYPE_NULL GValue) |
gchar* gda_parameter_get_value_str (GdaParameter *param);
Get a string representation of the value stored in param
. Calling
gda_parameter_set_value_str()
with this value will restore param
's current
state.
|
a GdaParameter object |
Returns : |
a new string, or NULL if param 's value is NULL
|
void gda_parameter_set_value (GdaParameter *param, const GValue *value);
|
|
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gboolean gda_parameter_set_value_str (GdaParameter *param, const gchar *value);
Same function as gda_parameter_set_value()
except that the value
is provided as a string, and may return FALSE if the string did not
represent a correct value for the data type of the parameter.
|
a GdaParameter object |
|
a value to set the parameter to, as a string |
Returns : |
TRUE if no error occurred |
void gda_parameter_declare_invalid (GdaParameter *param);
Forces a parameter to be invalid; to set it valid again, a new value must be assigned
to it using gda_parameter_set_value()
.
|
a GdaParameter object |
gboolean gda_parameter_is_valid (GdaParameter *param);
Get the validity of param
(that is, of the value held by param
)
|
a GdaParameter object |
Returns : |
TRUE if param 's value can safely be used
|
const GValue* gda_parameter_get_default_value (GdaParameter *param);
Get the default value held into the parameter. WARNING: the default value does not need to be of
the same type as the one required by param
.
|
a GdaParameter object |
Returns : |
the default value |
void gda_parameter_set_default_value (GdaParameter *param, const GValue *value);
|
|
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gboolean gda_parameter_get_exists_default_value (GdaParameter *param);
|
a GdaParameter object |
Returns : |
TRUE if param has a default value (which may be unspecified)
|
void gda_parameter_set_exists_default_value (GdaParameter *param, gboolean default_value_exists);
Tells if param
has default unspecified value. This function is usefull
if one wants to inform that param
has a default value but does not know
what that default value actually is.
|
|
|
void gda_parameter_set_not_null (GdaParameter *param, gboolean not_null);
Sets if the parameter can have a NULL value. If not_null
is TRUE, then that won't be allowed
|
a GdaParameter object |
|
gboolean gda_parameter_get_not_null (GdaParameter *param);
Get wether the parameter can be NULL or not
|
a GdaParameter object |
Returns : |
TRUE if the parameter cannot be NULL |
gboolean gda_parameter_restrict_values (GdaParameter *param, GdaDataModel *model, gint col, GError **error);
Sets a limit on the possible values for the param
parameter: the value must be among the values
contained in the col
column of the model
data model.
|
a GdaParameter object |
|
a GdaDataModel object or NULL |
|
the reference column in model
|
|
location to store error, or NULL
|
Returns : |
TRUE if no error occurred |
gboolean gda_parameter_has_restrict_values (GdaParameter *param, GdaDataModel **model, gint *col);
Tells if param
has its values restricted by a GdaDataModel, and optionally
allows to fetch the restrictions.
|
a GdaParameter |
|
a place to store a pointer to the model restricting the parameter, or NULL .
|
|
a place to store the column in the model restricting the parameter, or NULL
|
Returns : |
TRUE if param has its values restricted.
|
void gda_parameter_bind_to_param (GdaParameter *param, GdaParameter *bind_to);
Sets param
to change when bind_to
changes (and does not make bind_to
change when param
changes)
|
a GdaParameter |
|
a GdaParameter or NULL
|
GdaParameter* gda_parameter_get_bind_param (GdaParameter *param);
Get the parameter which makes param
change its value when the param's value is changed.
|
a GdaParameter |
Returns : |
the GdaParameter or NULL
|
"restrict-column"
property"restrict-column" gint : Read / Write
Allowed values: >= 0
Default value: 0
"restrict-changed"
signalvoid user_function (GdaParameter *gdaparameter, gpointer user_data) : Run First
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the object which received the signal. |
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user data set when the signal handler was connected. |