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The Q3DataBrowser class provides data manipulation and navigation for data entry forms. More...
#include <Q3DataBrowser>
This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.
Note to Qt Desktop Light Edition users: This class is only available in the Qt Desktop Edition.
Inherits QWidget.
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The Q3DataBrowser class provides data manipulation and navigation for data entry forms.
A high-level API is provided for navigating through data records in a cursor, for inserting, updating and deleting records, and for refreshing data in the display.
If you want a read-only form to present database data use Q3DataView; if you want a table-based presentation of your data use Q3DataTable.
A Q3DataBrowser is used to associate a dataset with a form in much the same way as a Q3DataTable associates a dataset with a table. Once the data browser has been constructed it can be associated with a dataset with setSqlCursor(), and with a form with setForm(). Boundary checking, sorting and filtering can be set with setBoundaryChecking(), setSort() and setFilter(), respectively.
The insertCurrent() function reads the fields from the default form into the default cursor and performs the insert. The updateCurrent() and deleteCurrent() functions perform similarly to update and delete the current record respectively.
The user can be asked to confirm all edits with setConfirmEdits(). For more precise control use setConfirmInsert(), setConfirmUpdate(), setConfirmDelete() and setConfirmCancels(). Use setAutoEdit() to control the behavior of the form when the user edits a record and then navigates.
The record set is navigated using first(), next(), prev(), last() and seek(). The form's display is updated with refresh(). When navigation takes place the firstRecordAvailable(), lastRecordAvailable(), nextRecordAvailable() and prevRecordAvailable() signals are emitted. When the cursor record is changed due to navigation the cursorChanged() signal is emitted.
If you want finer control of the insert, update and delete processes then you can use the lower level functions to perform these operations as described below.
The form is populated with data from the database with readFields(). If the user is allowed to edit, (see setReadOnly()), write the form's data back to the cursor's edit buffer with writeFields(). You can clear the values in the form with clearValues(). Editing is performed as follows:
This enum describes where the data browser is positioned.
| Constant | Value | Description |
|---|---|---|
| Q3DataBrowser::Unknown | 0 | the boundary cannot be determined (usually because there is no default cursor, or the default cursor is not active). |
| Q3DataBrowser::None | 1 | the browser is not positioned on a boundary, but it is positioned on a record somewhere in the middle. |
| Q3DataBrowser::BeforeBeginning | 2 | the browser is positioned before the first available record. |
| Q3DataBrowser::Beginning | 3 | the browser is positioned at the first record. |
| Q3DataBrowser::End | 4 | the browser is positioned at the last record. |
| Q3DataBrowser::AfterEnd | 5 | the browser is positioned after the last available record. |
This property holds whether the browser automatically applies edits.
The default value for this property is true. When the user begins an insertion or an update on a form there are two possible outcomes when they navigate to another record:
Access functions:
This property holds whether boundary checking is active.
When boundary checking is active (the default), signals are emitted indicating the current position of the default cursor.
Access functions:
See also boundary().
This property holds whether the browser confirms cancel operations.
If this property is true, all cancels must be confirmed by the user through a message box (this behavior can be changed by overriding the confirmCancel() function), otherwise all cancels occur immediately. The default is false.
Access functions:
See also confirmEdits() and confirmCancel().
This property holds whether the browser confirms deletions.
If this property is true, the browser confirms deletions, otherwise deletions happen immediately.
Access functions:
See also confirmCancels(), confirmEdits(), confirmUpdate(), confirmInsert(), and confirmEdit().
This property holds whether the browser confirms edits.
If this property is true, the browser confirms all edit operations (insertions, updates and deletions), otherwise all edit operations happen immediately. Confirmation is achieved by presenting the user with a message box -- this behavior can be changed by reimplementing the confirmEdit() function,
Access functions:
See also confirmEdit(), confirmCancels(), confirmInsert(), confirmUpdate(), and confirmDelete().
This property holds whether the data browser confirms insertions.
If this property is true, the browser confirms insertions, otherwise insertions happen immediately.
Access functions:
See also confirmCancels(), confirmEdits(), confirmUpdate(), confirmDelete(), and confirmEdit().
This property holds whether the browser confirms updates.
If this property is true, the browser confirms updates, otherwise updates happen immediately.
Access functions:
See also confirmCancels(), confirmEdits(), confirmInsert(), confirmDelete(), and confirmEdit().
This property holds the data browser's filter.
The filter applies to the data shown in the browser. Call refresh() to apply the new filter. A filter is a string containing a SQL WHERE clause without the WHERE keyword, e.g. "id>1000", "name LIKE 'A%'", etc.
There is no default filter.
Access functions:
See also sort().
This property holds whether the browser is read-only.
The default is false, i.e. data can be edited. If the data browser is read-only, no database edits will be allowed.
Access functions:
This property holds the data browser's sort.
The data browser's sort affects the order in which records are viewed in the browser. Call refresh() to apply the new sort.
When retrieving the sort property, a string list is returned in the form 'fieldname order', e.g. 'id ASC', 'surname DESC'.
There is no default sort.
Note that if you want to iterate over the list, you should iterate over a copy, e.g.
QStringList list = myDataBrowser.sort();
QStringList::Iterator it = list.begin();
while(it != list.end()) {
myProcessing(*it);
++it;
}
Access functions:
Constructs a data browser which is a child of parent, with the name name and widget flags set to fl.
Destroys the object and frees any allocated resources.
This signal is emitted just before the cursor's edit buffer is deleted from the database. The buf parameter points to the edit buffer being deleted. You might connect to this signal to capture some auditing information about the deletion.
This signal is emitted just before the cursor's edit buffer is inserted into the database. The buf parameter points to the edit buffer being inserted. You might connect to this signal to populate a generated primary key for example.
This signal is emitted just before the cursor's edit buffer is updated in the database. The buf parameter points to the edit buffer being updated. You might connect to this signal to capture some auditing information about the update.
Returns an enum indicating the boundary status of the browser.
This is achieved by moving the default cursor and checking the position, however the current default form values will not be altered. After checking for the boundary, the cursor is moved back to its former position. See Q3DataBrowser::Boundary.
See also Boundary.
Clears all the values in the form.
All the edit buffer field values are set to their 'zero state', e.g. 0 for numeric fields and "" for string fields. Then the widgets are updated using the property map. For example, a combobox that is property-mapped to integers would scroll to the first item. See the Q3SqlPropertyMap constructor for the default mappings of widgets to properties.
Protected virtual function which returns a confirmation for canceling an edit mode m. Derived classes can reimplement this function and provide their own confirmation dialog. The default implementation uses a message box which prompts the user to confirm the edit action.
Protected virtual function which returns a confirmation for an edit of mode m. Derived classes can reimplement this function and provide their own confirmation dialog. The default implementation uses a message box which prompts the user to confirm the edit action.
This signal is emitted whenever the current cursor position changes. The record parameter points to the contents of the current cursor's record.
Returns true if the form's edit buffer differs from the current cursor buffer; otherwise returns false.
This signal is emitted whenever the cursor record was changed due to navigation. The mode parameter is the edit that just took place, e.g. Insert, Update or Delete. See Q3SqlCursor::Mode.
Performs a delete operation on the data browser's cursor. If there is no default cursor or no default form, nothing happens.
Otherwise, the following happens:
The current form's record is deleted from the database, providing that the data browser is not in insert mode. If the data browser is actively inserting a record (see insert()), the insert action is canceled, and the browser navigates to the last valid record that was current. If there is an error, handleError() is called.
Performs a delete on the default cursor using the values from the default form and updates the default form. If there is no default form or no default cursor, nothing happens. If the deletion was successful, the cursor is repositioned to the nearest record and true is returned. The nearest record is the next record if there is one otherwise the previous record if there is one. If an error occurred during the deletion from the database, handleError() is called and false is returned.
See also cursor(), form(), and handleError().
Moves the default cursor to the first record and refreshes the default form to display this record. If there is no default form or no default cursor, nothing happens. If the data browser successfully navigated to the first record, the default cursor is primed for update and the primeUpdate() signal is emitted.
If the browser is already positioned on the first record nothing happens.
This signal is emitted whenever the position of the cursor changes. The available parameter indicates whether or not the first record in the default cursor is available.
Returns the data browser's default form or 0 if no form has been set.
See also setForm().
Virtual function which handles the error error. The default implementation warns the user with a message box.
Performs an insert operation on the data browser's cursor. If there is no default cursor or no default form, nothing happens.
If auto-editing is on (see setAutoEdit()), the following happens:
If there is an error handling any of the above auto-edit actions, handleError() is called and no insert or update is performed.
If no error occurred, or auto-editing is not enabled, the data browser begins actively inserting a record into the database by performing the following actions:
Reads the fields from the default form into the default cursor and performs an insert on the default cursor. If there is no default form or no default cursor, nothing happens. If an error occurred during the insert into the database, handleError() is called and false is returned. If the insert was successful, the cursor is refreshed and relocated to the newly inserted record, the cursorChanged() signal is emitted, and true is returned.
See also cursorChanged(), sqlCursor(), form(), and handleError().
Moves the default cursor to the last record and refreshes the default form to display this record. If there is no default form or no default cursor, nothing happens. If the data browser successfully navigated to the last record, the default cursor is primed for update and the primeUpdate() signal is emitted.
If the browser is already positioned on the last record nothing happens.
This signal is emitted whenever the position of the cursor changes. The available parameter indicates whether or not the last record in the default cursor is available.
Moves the default cursor to the next record and refreshes the default form to display this record. If there is no default form or no default cursor, nothing happens. If the data browser successfully navigated to the next record, the default cursor is primed for update and the primeUpdate() signal is emitted.
If the browser is positioned on the last record nothing happens.
This signal is emitted whenever the position of the cursor changes. The available parameter indicates whether or not the next record in the default cursor is available.
Moves the default cursor to the previous record and refreshes the default form to display this record. If there is no default form or no default cursor, nothing happens. If the data browser successfully navigated to the previous record, the default cursor is primed for update and the primeUpdate() signal is emitted.
If the browser is positioned on the first record nothing happens.
This signal is emitted whenever the position of the cursor changes. The available parameter indicates whether or not the previous record in the default cursor is available.
This signal is emitted when the data browser enters deletion mode. The buf parameter points to the record buffer being deleted. (Note that Q3SqlCursor::primeDelete() is not called on the default cursor, as this would corrupt values in the form.) Connect to this signal in order to, for example, save a copy of the deleted record for auditing purposes.
See also del().
This signal is emitted when the data browser enters insertion mode. The buf parameter points to the record buffer that is to be inserted. Connect to this signal to, for example, prime the record buffer with default data values, auto-numbered fields etc. (Note that Q3SqlCursor::primeInsert() is not called on the default cursor, as this would corrupt values in the form.)
See also insert().
This signal is emitted when the data browser enters update mode. Note that during navigation (first(), last(), next(), prev()), each record that is shown in the default form is primed for update. The buf parameter points to the record buffer being updated. (Note that Q3SqlCursor::primeUpdate() is not called on the default cursor, as this would corrupt values in the form.) Connect to this signal in order to, for example, keep track of which records have been updated, perhaps for auditing purposes.
See also update().
Reads the fields from the default cursor's edit buffer and displays them in the form. If there is no default cursor or no default form, nothing happens.
Refreshes the data browser's data using the default cursor. The browser's current filter and sort are applied if they have been set.
See also setFilter() and setSort().
Moves the default cursor to the record specified by index i and refreshes the default form to display that record. If there is no default form or no default cursor, nothing happens. If relative is true (the default is false), the cursor is moved relative to its current position. If the data browser successfully navigated to the desired record, the default cursor is primed for update and the primeUpdate() signal is emitted.
If the browser is already positioned on the desired record nothing happens. Returns false if there is no cursor. Otherwise returns true.
Sets the browser's default form to form. The cursor and all navigation and data manipulation functions that the browser provides become available to the form.
See also form().
Sets the default cursor used by the data browser to cursor. If autoDelete is true (the default is false), the data browser takes ownership of the cursor pointer, which will be deleted when the browser is destroyed, or when setSqlCursor() is called again. To activate the cursor use refresh(). The cursor's edit buffer is used in the default form to browse and edit records.
See also sqlCursor(), form(), and setForm().
Returns the default cursor used for navigation, or 0 if there is no default cursor.
See also setSqlCursor().
Performs an update operation on the data browser's cursor.
If there is no default cursor or no default form, nothing happens. Otherwise, the following happens:
If the data browser is actively inserting a record (see insert()), that record is inserted into the database using insertCurrent(). Otherwise, the database is updated with the current form's data using updateCurrent(). If there is an error handling either action, handleError() is called.
If boundaryChecking() is true, checks the boundary of the current default cursor and emits signals which indicate the position of the cursor.
Reads the fields from the default form into the default cursor and performs an update on the default cursor. If there is no default form or no default cursor, nothing happens. If an error occurred during the update on the database, handleError() is called and false is returned. If the update was successful, the cursor is refreshed and relocated to the updated record, the cursorChanged() signal is emitted, and true is returned.
See also cursor(), form(), and handleError().
Writes the form's data to the default cursor's edit buffer. If there is no default cursor or no default form, nothing happens.
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