GdaDataProxy

GdaDataProxy — Proxy to hold modifications for any GdaDataModel, providing the GdaDataModel interface itself

Stability Level

Stable, unless otherwise indicated

Properties

gboolean cache-changes Read / Write
gboolean defer-sync Read / Write
GdaDataModel * model Read / Write / Construct
gboolean prepend-null-entry Read / Write
gint sample-size Read / Write / Construct

Signals

void filter-changed Run First
void row-changes-applied Run First
void row-delete-changed Run First
void sample-changed Run First
void sample-size-changed Run First
GError* validate-row-changes Run Last

Object Hierarchy

    GObject
    ╰── GdaDataProxy

Implemented Interfaces

GdaDataProxy implements GdaDataModel.

Description

This object stores modifications to be made to a GdaDataModel object which is proxied until the modifications are actually written to the GdaDataModel, it can also filter the proxied data model to show only a subset (a defined number of continuous rows or by a filter to apply).

Specifically, for a proxied data model having nb_cols columns and nb_rows rows, the GdaDataProxy object has the following attributes:

  • 2 * nb_cols columns:

    • the first (>= 0) nb_cols columns are the current values stored in the proxy (which correspond to the values of the proxied data model if the considered row has not been changed). The associated values are writable.

    • the last nb_cols columns are the values stored in the proxied data model, at column col - nb_cols

  • a variable number of rows depending on the following attributes:

    • if the proxy is configured to have an empty row as the first row

    • if the proxy only displays parts of the proxied data model

    • if new rows have been added to the proxy

  • Any GdaDataModelIter iterator created will only make appear the colmuns as present in the proxied data model, not any of the other columns

This situation is illustrated in the following schema, where there is a direct mapping between the proxy's rows and the proxied data model's rows:

GdaDataProxy's values mapping regarding the proxied data model

Note that unless explicitly mentioned, the columns are read-only.

The following figures illustrate row mappings between the data proxy and the proxied data model in several situations (which can be combined, but are shown alone for simplicity):

  • situation where rows 1 and 5 have been marked as deleted from the data proxy, using gda_data_proxy_delete() method, the data proxy has 2 rows less than the proxied data model:

    GdaDataProxy with 2 rows marked as deleted

  • situation where the data proxy only shows a sample of the proxied data model at any given time, using the gda_data_proxy_set_sample_size() method (the sample here is 4 rows wide, and starts at row 3):

    GdaDataProxy with a sample size of 4

  • situation where the data proxy shows a row of NULL values, using the "prepend-null-entry" property:

    GdaDataProxy with an extra row of NULL values

  • situation where a row has been added to the data proxy, using for example the gda_data_model_append_row() method:

    GdaDataProxy where a row has been added

The GdaDataProxy objects are thread safe, which means any proxy object can be used from any thread at the same time as they implement their own locking mechanisms.

Functions

gda_data_proxy_new ()

GObject *
gda_data_proxy_new (GdaDataModel *model);

Creates a new proxy for model . For bindings use gda_data_proxy_new_with_data_model .

Parameters

model

Data model to be proxied.

[transfer none]

Returns

a new GdaDataProxy object.

[transfer full]


gda_data_proxy_get_proxied_model ()

GdaDataModel *
gda_data_proxy_get_proxied_model (GdaDataProxy *proxy);

Fetch the GdaDataModel which proxy does proxy

Parameters

proxy

a GdaDataProxy object

 

Returns

the proxied data model.

[transfer none]


gda_data_proxy_get_proxied_model_n_cols ()

gint
gda_data_proxy_get_proxied_model_n_cols
                               (GdaDataProxy *proxy);

Get the number of columns in the proxied data model

Parameters

proxy

a GdaDataProxy object

 

Returns

the number of columns, or -1 if an error occurred


gda_data_proxy_get_proxied_model_n_rows ()

gint
gda_data_proxy_get_proxied_model_n_rows
                               (GdaDataProxy *proxy);

Get the number of rows in the proxied data model

Parameters

proxy

a GdaDataProxy object

 

Returns

the number of rows, or -1 if the number of rows is not known


gda_data_proxy_is_read_only ()

gboolean
gda_data_proxy_is_read_only (GdaDataProxy *proxy);

Parameters

proxy

a GdaDataProxy object

 

Returns

TRUE if the proxied data model is itself read-only


gda_data_proxy_get_values ()

GSList *
gda_data_proxy_get_values (GdaDataProxy *proxy,
                           gint proxy_row,
                           gint *cols_index,
                           gint n_cols);

Retrieve a whole list of values from the proxy data model. This function calls gda_data_proxy_get_value() for each column index specified in cols_index , and generates a GSList on the way.

Parameters

proxy

a GdaDataProxy object

 

proxy_row

a proxy row

 

cols_index

array containing the columns for which the values are requested.

[array][array length=n_cols]

n_cols

size of cols_index

 

Returns

a new list of values (the list must be freed, not the values), or NULL if an error occurred.

[element-type GValue][transfer container]


gda_data_proxy_get_value_attributes ()

GdaValueAttribute
gda_data_proxy_get_value_attributes (GdaDataProxy *proxy,
                                     gint proxy_row,
                                     gint col);

Get the attributes of the value stored at (proxy_row, col) in proxy , which is an ORed value of GdaValueAttribute flags

Parameters

proxy

a GdaDataProxy object

 

proxy_row

a proxy row

 

col

a valid proxy column

 

Returns

a GdaValueAttribute with the value's attributes at given position


gda_data_proxy_alter_value_attributes ()

void
gda_data_proxy_alter_value_attributes (GdaDataProxy *proxy,
                                       gint proxy_row,
                                       gint col,
                                       GdaValueAttribute alter_flags);

Alters the attributes of the value stored at (proxy_row, col) in proxy . the alter_flags can only contain the GDA_VALUE_ATTR_IS_NULL, GDA_VALUE_ATTR_IS_DEFAULT and GDA_VALUE_ATTR_IS_UNCHANGED flags (other flags are ignored).

Parameters

proxy

a GdaDataProxy object

 

proxy_row

A proxy row number

 

col

a valid column number

 

alter_flags

flags to alter the attributes.

[transfer none]

gda_data_proxy_get_proxied_model_row ()

gint
gda_data_proxy_get_proxied_model_row (GdaDataProxy *proxy,
                                      gint proxy_row);

Get the proxy 's proxied model row corresponding to proxy_row

Parameters

proxy

a GdaDataProxy object

 

proxy_row

A proxy row number

 

Returns

the proxied model's row, or -1 if proxy row which only exists proxy


gda_data_proxy_delete ()

void
gda_data_proxy_delete (GdaDataProxy *proxy,
                       gint proxy_row);

Marks the row proxy_row to be deleted

Parameters

proxy

a GdaDataProxy object

 

proxy_row

A proxy row number

 

gda_data_proxy_undelete ()

void
gda_data_proxy_undelete (GdaDataProxy *proxy,
                         gint proxy_row);

Remove the "to be deleted" mark at the row proxy_row , if it existed.

Parameters

proxy

a GdaDataProxy object

 

proxy_row

A proxy row number

 

gda_data_proxy_row_is_deleted ()

gboolean
gda_data_proxy_row_is_deleted (GdaDataProxy *proxy,
                               gint proxy_row);

Tells if the row number proxy_row is marked to be deleted.

Parameters

proxy

a GdaDataProxy object

 

proxy_row

A proxy row number

 

Returns

TRUE if the row is marked to be deleted


gda_data_proxy_row_is_inserted ()

gboolean
gda_data_proxy_row_is_inserted (GdaDataProxy *proxy,
                                gint proxy_row);

Tells if the row number proxy_row is a row which has been inserted in proxy (and is thus not in the proxied data model).

Parameters

proxy

a GdaDataProxy object

 

proxy_row

A proxy row number

 

Returns

TRUE if the row is an inserted row


gda_data_proxy_cancel_row_changes ()

void
gda_data_proxy_cancel_row_changes (GdaDataProxy *proxy,
                                   gint proxy_row,
                                   gint col);

Resets data at the corresponding row and column. If proxy_row corresponds to a new row, then that new row is deleted from proxy .

Parameters

proxy

a GdaDataProxy object

 

proxy_row

the row to cancel changes

 

col

the column to cancel changes, or less than 0 to cancel any change on the row row

 

gda_data_proxy_apply_row_changes ()

gboolean
gda_data_proxy_apply_row_changes (GdaDataProxy *proxy,
                                  gint proxy_row,
                                  GError **error);

Commits the modified data in the proxy back into the GdaDataModel.

Parameters

proxy

a GdaDataProxy object

 

proxy_row

the row number to commit

 

error

place to store the error, or NULL

 

Returns

TRUE if no error occurred.


gda_data_proxy_has_changed ()

gboolean
gda_data_proxy_has_changed (GdaDataProxy *proxy);

Tells if proxy contains any modifications not applied to the proxied data model.

Parameters

proxy

a GdaDataProxy object

 

Returns

TRUE if there are some modifications in proxy


gda_data_proxy_row_has_changed ()

gboolean
gda_data_proxy_row_has_changed (GdaDataProxy *proxy,
                                gint proxy_row);

Tells if the row number proxy_row has changed

Parameters

proxy

a GdaDataProxy object

 

proxy_row

A proxy row number

 

Returns

TRUE if the row has changed


gda_data_proxy_get_n_new_rows ()

gint
gda_data_proxy_get_n_new_rows (GdaDataProxy *proxy);

Get the number of rows which have been added to proxy and which are not part of the proxied data model.

Parameters

proxy

a GdaDataProxy object

 

Returns

the number of new rows


gda_data_proxy_set_sample_size ()

void
gda_data_proxy_set_sample_size (GdaDataProxy *proxy,
                                gint sample_size);

Sets the size of each chunk of data to display: the maximum number of rows which can be "displayed" at a time (the maximum number of rows which proxy pretends to have). The default value is arbitrary 300 as it is big enough to be able to display quite a lot of data, but small enough to avoid too much data displayed at the same time.

Note: the rows which have been added but not yet committed will always be displayed regardless of the current chunk of data, and the modified rows which are not visible when the displayed chunk of data changes are still held as modified rows.

To remove the chunking of the data to display, simply pass sample_size the 0 value.

Parameters

proxy

a GdaDataProxy object

 

sample_size

the requested size of a chunk, or 0

 

gda_data_proxy_get_sample_size ()

gint
gda_data_proxy_get_sample_size (GdaDataProxy *proxy);

Get the size of each chunk of data displayed at a time.

Parameters

proxy

a GdaDataProxy object

 

Returns

the chunk (or sample) size, or 0 if chunking is disabled.


gda_data_proxy_set_sample_start ()

void
gda_data_proxy_set_sample_start (GdaDataProxy *proxy,
                                 gint sample_start);

Sets the number of the first row to be available in proxy (in reference to the proxied data model)

Parameters

proxy

a GdaDataProxy object

 

sample_start

the number of the first row to be displayed

 

gda_data_proxy_get_sample_start ()

gint
gda_data_proxy_get_sample_start (GdaDataProxy *proxy);

Get the number of the first row to be available in proxy (in reference to the proxied data model)

Parameters

proxy

a GdaDataProxy object

 

Returns

the number of the first proxied model's row.


gda_data_proxy_get_sample_end ()

gint
gda_data_proxy_get_sample_end (GdaDataProxy *proxy);

Get the number of the last row to be available in proxy (in reference to the proxied data model)

Parameters

proxy

a GdaDataProxy object

 

Returns

the number of the last proxied model's row.


gda_data_proxy_apply_all_changes ()

gboolean
gda_data_proxy_apply_all_changes (GdaDataProxy *proxy,
                                  GError **error);

Apply all the changes stored in the proxy to the proxied data model. The changes are done row after row, and if an error occurs, then it is possible that not all the changes to all the rows have been applied.

Parameters

proxy

a GdaDataProxy object

 

error

a place to store errors, or NULL

 

Returns

TRUE if no error occurred


gda_data_proxy_cancel_all_changes ()

gboolean
gda_data_proxy_cancel_all_changes (GdaDataProxy *proxy);

Cancel all the changes stored in the proxy (the proxy will be reset to its state as it was just after creation). Note that if there are some cached changes (i.e. not applied to the current proxied data model), then these cached changes are not cleared (set the "cache-changes" property to FALSE for this).

Parameters

proxy

a GdaDataProxy object

 

Returns

TRUE if no error occurred


gda_data_proxy_set_filter_expr ()

gboolean
gda_data_proxy_set_filter_expr (GdaDataProxy *proxy,
                                const gchar *filter_expr,
                                GError **error);

Sets a filter among the rows presented by proxy . The filter is defined by a filter expression which can be any SQL valid expression using proxy 's columns. For instance if proxy has the "id" and "name" columns, then a filter can be "length(name) < 5" to filter only the rows where the length of the name is strictly inferior to 5, or "id >= 1000 and id < 2000 order by name limit 50" to filter only the rows where the id is between 1000 and 2000, ordered by name and limited to 50 rows.

Note about column names: real column names can be used (double quoted if necessary), but columns can also be named "_<column number>" with column numbers starting at 1.

Note that any previous filter expression is replaced with the new filter_expr if no error occurs (if an error occurs, then any previous filter is left unchanged).

Parameters

proxy

a GdaDataProxy object

 

filter_expr

an SQL based expression which will filter the contents of proxy , or NULL to remove any previous filter.

[allow-none]

error

a place to store errors, or NULL

 

Returns

TRUE if no error occurred


gda_data_proxy_get_filter_expr ()

const gchar *
gda_data_proxy_get_filter_expr (GdaDataProxy *proxy);

Get the current filter expression used by proxy .

Parameters

proxy

a GdaDataProxy object

 

Returns

the current filter expression or NULL if no filter has been set


gda_data_proxy_get_filtered_n_rows ()

gint
gda_data_proxy_get_filtered_n_rows (GdaDataProxy *proxy);

Get the total number of filtered rows in proxy if a filter has been applied. As new rows (rows added to the proxy and not yet added to the proxied data model) and rows to remove (rows marked for removal but not yet removed from the proxied data model) are also filtered, the returned number also contains references to new rows and rows to be removed.

Parameters

proxy

a GdaDataProxy object

 

Returns

the number of filtered rows in proxy , or -1 if no filter has been applied

Types and Values

GdaDataProxy

typedef struct _GdaDataProxy GdaDataProxy;

GdaDataProxyClass

typedef struct {
	GObjectClass            parent_class;

	void                 (* row_delete_changed)   (GdaDataProxy *proxy, gint row, gboolean to_be_deleted);

	void                 (* sample_size_changed)  (GdaDataProxy *proxy, gint sample_size);
	void                 (* sample_changed)       (GdaDataProxy *proxy, gint sample_start, gint sample_end);

	GError              *(* validate_row_changes) (GdaDataProxy *proxy, gint row, gint proxied_row);
	void                 (* row_changes_applied)  (GdaDataProxy *proxy, gint row, gint proxied_row);

	void                 (* filter_changed)       (GdaDataProxy *proxy);
} GdaDataProxyClass;

GdaDataProxyPrivate

typedef struct _GdaDataProxyPrivate GdaDataProxyPrivate;

Property Details

The “cache-changes” property

  “cache-changes”            gboolean

Defines how changes kept in the data proxy are handled when the proxied data model is changed (using the "model" property). The default is to silently discard all the changes, but if this property is set to TRUE, then the changes are cached.

If set to TRUE, each cached change will be re-applied to a newly set proxied data model if the change's number of columns match the proxied data model's number of columns and based on:

  • the contents of the proxied data model's modified row for updates and deletes

  • the inserts are always kept

Flags: Read / Write

Default value: FALSE

Since 5.2


The “defer-sync” property

  “defer-sync”               gboolean

Tells if changes to the sample of rows displayed is done in background in several steps or if it's done in one step.

Flags: Read / Write

Default value: TRUE


The “model” property

  “model”                    GdaDataModel *

Proxied data model.

Flags: Read / Write / Construct


The “prepend-null-entry” property

  “prepend-null-entry”       gboolean

Tells if a row composed of NULL values is inserted as the proxy's first row.

Flags: Read / Write

Default value: FALSE


The “sample-size” property

  “sample-size”              gint

Number of rows which the proxy will contain at any time, like a sliding window on the proxied data model.

Flags: Read / Write / Construct

Allowed values: [0,2147483646]

Default value: 300

Signal Details

The “filter-changed” signal

void
user_function (GdaDataProxy *proxy,
               gpointer      user_data)

Gets emitted when proxy 's filter has been changed

Parameters

proxy

the GdaDataProxy

 

user_data

user data set when the signal handler was connected.

 

Flags: Run First


The “row-changes-applied” signal

void
user_function (GdaDataProxy *proxy,
               gint          row,
               gint          proxied_row,
               gpointer      user_data)

Gets emitted when proxy has committed a row change to the proxied data model.

Parameters

proxy

the GdaDataProxy

 

row

the proxy's row

 

proxied_row

the proxied data model's row

 

user_data

user data set when the signal handler was connected.

 

Flags: Run First


The “row-delete-changed” signal

void
user_function (GdaDataProxy *proxy,
               gint          row,
               gboolean      to_be_deleted,
               gpointer      user_data)

Gets emitted whenever a row has been marked to be deleted, or has been unmarked to be deleted

Parameters

proxy

the GdaDataProxy

 

row

the concerned proxy 's row

 

to_be_deleted

tells if the row is marked to be deleted

 

user_data

user data set when the signal handler was connected.

 

Flags: Run First


The “sample-changed” signal

void
user_function (GdaDataProxy *proxy,
               gint          sample_start,
               gint          sample_end,
               gpointer      user_data)

Gets emitted whenever proxy 's sample size has been changed. sample_start and sample_end are in reference to the proxied data model.

Parameters

proxy

the GdaDataProxy

 

sample_start

the first row of the sample

 

sample_end

the last row of the sample

 

user_data

user data set when the signal handler was connected.

 

Flags: Run First


The “sample-size-changed” signal

void
user_function (GdaDataProxy *proxy,
               gint          sample_size,
               gpointer      user_data)

Gets emitted whenever proxy 's sample size has been changed

Parameters

proxy

the GdaDataProxy

 

sample_size

the new sample size

 

user_data

user data set when the signal handler was connected.

 

Flags: Run First


The “validate-row-changes” signal

GError*
user_function (GdaDataProxy *proxy,
               gint          row,
               gint          proxied_row,
               gpointer      user_data)

Gets emitted when proxy is about to commit a row change to the proxied data model. If any callback returns a non NULL value, then the change commit fails with the returned GError

Parameters

proxy

the GdaDataProxy

 

row

the proxy's row

 

proxied_row

the proxied data model's row

 

user_data

user data set when the signal handler was connected.

 

Returns

a new GError if validation failed, or NULL

Flags: Run Last

See Also

GdaDataModel