## GdaDataProxy GdaDataProxy — Proxy to hold modifications for any GdaDataModel, and provides the GdaDataModel interface itself |

## Synopsis

                        GdaDataProxy;
                        GdaDataProxyClass;
                        GdaDataProxyPrivate;
    GObject*            gda_data_proxy_new                  (GdaDataModel *model);
    GdaDataModel*       gda_data_proxy_get_proxied_model    (GdaDataProxy *proxy);
    gint                gda_data_proxy_get_proxied_model_n_cols
                                                            (GdaDataProxy *proxy);
    gint                gda_data_proxy_get_proxied_model_n_rows
                                                            (GdaDataProxy *proxy);
    gboolean            gda_data_proxy_is_read_only         (GdaDataProxy *proxy);
    GSList*             gda_data_proxy_get_values           (GdaDataProxy *proxy,
                                                             gint proxy_row,
                                                             gint *cols_index,
                                                             gint n_cols);
    GdaValueAttribute   gda_data_proxy_get_value_attributes (GdaDataProxy *proxy,
                                                             gint proxy_row,
                                                             gint col);
    void                gda_data_proxy_alter_value_attributes
                                                            (GdaDataProxy *proxy,
                                                             gint proxy_row,
                                                             gint col,
                                                             GdaValueAttribute alter_flags);
    gint                gda_data_proxy_get_proxied_model_row
                                                            (GdaDataProxy *proxy,
                                                             gint proxy_row);
    void                gda_data_proxy_delete               (GdaDataProxy *proxy,
                                                             gint proxy_row);
    void                gda_data_proxy_undelete             (GdaDataProxy *proxy,
                                                             gint proxy_row);
    gboolean            gda_data_proxy_row_is_deleted       (GdaDataProxy *proxy,
                                                             gint proxy_row);
    gboolean            gda_data_proxy_row_is_inserted      (GdaDataProxy *proxy,
                                                             gint proxy_row);
    gint                gda_data_proxy_find_row_from_values (GdaDataProxy *proxy,
                                                             GSList *values,
                                                             gint *cols_index);
    void                gda_data_proxy_cancel_row_changes   (GdaDataProxy *proxy,
                                                             gint proxy_row,
                                                             gint col);
    gboolean            gda_data_proxy_apply_row_changes    (GdaDataProxy *proxy,
                                                             gint proxy_row,
                                                             GError **error);
    gboolean            gda_data_proxy_has_changed          (GdaDataProxy *proxy);
    gboolean            gda_data_proxy_row_has_changed      (GdaDataProxy *proxy,
                                                             gint proxy_row);
    gint                gda_data_proxy_get_n_new_rows       (GdaDataProxy *proxy);
    void                gda_data_proxy_set_sample_size      (GdaDataProxy *proxy,
                                                             gint sample_size);
    gint                gda_data_proxy_get_sample_size      (GdaDataProxy *proxy);
    void                gda_data_proxy_set_sample_start     (GdaDataProxy *proxy,
                                                             gint sample_start);
    gint                gda_data_proxy_get_sample_start     (GdaDataProxy *proxy);
    gint                gda_data_proxy_get_sample_end       (GdaDataProxy *proxy);
    gboolean            gda_data_proxy_apply_all_changes    (GdaDataProxy *proxy,
                                                             GError **error);
    gboolean            gda_data_proxy_cancel_all_changes   (GdaDataProxy *proxy);
    gboolean            gda_data_proxy_set_filter_expr      (GdaDataProxy *proxy,
                                                             const gchar *filter_expr,
                                                             GError **error);
    const gchar*        gda_data_proxy_get_filter_expr      (GdaDataProxy *proxy);
    gint                gda_data_proxy_get_filtered_n_rows  (GdaDataProxy *proxy);

## Object Hierarchy

      GObject
       +----GdaObject
             +----GdaDataProxy

## Implemented Interfaces

GdaDataProxy implements GdaDataModel.

## Properties

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

## Signals

      "filter-changed"                                 : Run First
      "post-changes-applied"                           : Run First
      "pre-changes-applied"                            : Run Last
      "row-delete-changed"                             : Run First
      "sample-changed"                                 : Run First
      "sample-size-changed"                            : Run First

## 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

Note that unless explicitely mentionned, the columns are read-only.

## Details

### GdaDataProxy

    typedef struct _GdaDataProxy GdaDataProxy;

### GdaDataProxyClass

    typedef struct {
    	GdaObjectClass          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);

    	gboolean             (* pre_changes_applied)  (GdaDataProxy *proxy, gint row, gint proxied_row);
    	void                 (* post_changes_applied) (GdaDataProxy *proxy, gint row, gint proxied_row);
    } GdaDataProxyClass;

### GdaDataProxyPrivate

    typedef struct _GdaDataProxyPrivate GdaDataProxyPrivate;

### gda_data_proxy_new ()

    GObject*            gda_data_proxy_new                  (GdaDataModel *model);

Creates a new proxy for `model`

`model` : | Data model to be proxied
Returns : | a new GdaDataProxy object

### gda_data_proxy_get_proxied_model ()

    GdaDataModel*       gda_data_proxy_get_proxied_model    (GdaDataProxy *proxy);

Fetch the GdaDataModel which `proxy` does proxy

`proxy` : | a GdaDataProxy object
Returns : | the proxied data model

### 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

`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

`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);

`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);

Retreive a whole list of values from the `proxy` store. This function calls `gda_data_proxy_get_value()` for each column index specified in `cols_index`, and generates a GSlist on the way.

`proxy` : | a GdaDataProxy object
`proxy_row` : | a proxy row
`cols_index` : |
`n_cols` : |
Returns : | a new list of values (the list must be freed, not the values), or `NULL` if an error occurred

### 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

`proxy` : | a GdaDataProxy object
`proxy_row` : | a proxy row
`col` : | a valid proxy column
Returns : | the attribute

### 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).

`proxy` : | a GdaDataProxy object
`proxy_row` : | A proxy row number
`col` : | a valid column number
`alter_flags` : | flags to alter the attributes

### 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`

`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

`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.

`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.

`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).

`proxy` : | a GdaDataProxy object
`proxy_row` : | A proxy row number
Returns : | TRUE if the row is an inserted row

### gda_data_proxy_find_row_from_values ()

    gint                gda_data_proxy_find_row_from_values (GdaDataProxy *proxy,
                                                             GSList *values,
                                                             gint *cols_index);

Find the first row where all the values in `values` at the columns identified at `cols_index` match.

NOTE: the `cols_index` array MUST contain a column index for each value in `values`

`proxy` : | a GdaDataProxy object
`values` : | a list of GValue values
`cols_index` : | an array of gint containing the column number to match each value of `values`
Returns : | proxy row number if the row has been identified, or -1 otherwise

### 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`.

`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.

`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.

`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

`proxy` : | a GdaDataProxy object
`proxy_row` : | A proxy row number
Returns : |

### 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.

`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 fata to display: the maximum number of rows which can be displayed at a time. 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 commited 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.

`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.

`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 displayed.

`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 row number of the first row to be displayed.

`proxy` : | a GdaDataProxy object
Returns : | the number of the first row being displayed.

### gda_data_proxy_get_sample_end ()

    gint                gda_data_proxy_get_sample_end       (GdaDataProxy *proxy);

Get the row number of the last row to be displayed.

`proxy` : | a GdaDataProxy object
Returns : | the number of the last row being displayed.

### 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.

`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).

`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 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).

`proxy` : | a GdaDataProxy object
`filter_expr` : | an SQL based expression which will filter the contents of `proxy`, or `NULL` to remove any previous filter
`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`.

`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 reefrences to new rows and rows to be removed.

`proxy` : | a GdaDataProxy object
Returns : | the number of filtered rows in `proxy`, or -1 if no filter has been applied

## Property Details

### The `"defer-sync"` property

      "defer-sync"               gboolean              : Read / Write

Default value: TRUE

### The `"model"` property

      "model"                    GdaDataModel*         : Read / Write / Construct

### The `"prepend-null-entry"` property

      "prepend-null-entry"       gboolean              : Read / Write

Default value: FALSE

### The `"sample-size"` property

      "sample-size"              gint                  : Read / Write / Construct

Allowed values: [0,2147483646]

Default value: 300

## Signal Details

### The `"filter-changed"` signal

    void                user_function                      (GdaDataProxy *gdadataproxy,
                                                            gpointer      user_data)         : Run First

`gdadataproxy` : | the object which received the signal.
`user_data` : | user data set when the signal handler was connected.

### The `"post-changes-applied"` signal

    void                user_function                      (GdaDataProxy *gdadataproxy,
                                                            gint          arg1,
                                                            gint          arg2,
                                                            gpointer      user_data)         : Run First

`gdadataproxy` : | the object which received the signal.
`arg1` : |
`arg2` : |
`user_data` : | user data set when the signal handler was connected.

### The `"pre-changes-applied"` signal

    gboolean            user_function                      (GdaDataProxy *gdadataproxy,
                                                            gint          arg1,
                                                            gint          arg2,
                                                            gpointer      user_data)         : Run Last

`gdadataproxy` : | the object which received the signal.
`arg1` : |
`arg2` : |
`user_data` : | user data set when the signal handler was connected.
Returns : |

### The `"row-delete-changed"` signal

    void                user_function                      (GdaDataProxy *gdadataproxy,
                                                            gint          arg1,
                                                            gboolean      arg2,
                                                            gpointer      user_data)         : Run First

`gdadataproxy` : | the object which received the signal.
`arg1` : |
`arg2` : |
`user_data` : | user data set when the signal handler was connected.

### The `"sample-changed"` signal

    void                user_function                      (GdaDataProxy *gdadataproxy,
                                                            gint          arg1,
                                                            gint          arg2,
                                                            gpointer      user_data)         : Run First

`gdadataproxy` : | the object which received the signal.
`arg1` : |
`arg2` : |
`user_data` : | user data set when the signal handler was connected.

### The `"sample-size-changed"` signal

    void                user_function                      (GdaDataProxy *gdadataproxy,
                                                            gint          arg1,
                                                            gpointer      user_data)         : Run First

`gdadataproxy` : | the object which received the signal.
`arg1` : |
`user_data` : | user data set when the signal handler was connected.