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.
A TQDataBrowser is used to associate a dataset with a form in much the same way as a TQDataTable 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.
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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 behaviour of the form when the user edits a record and then navigates.
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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.
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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.
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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:
.TP
\fIinsert\fR When the data browser enters insertion mode it emits the primeInsert() signal which you can connect to, for example to pre-populate fields. Call writeFields() to write the user's edits to the cursor's edit buffer then call insert() to insert the record into the database. The beforeInsert() signal is emitted just before the cursor's edit buffer is inserted into the database; connect to this for example, to populate fields such as an auto-generated primary key.
.TP
\fIupdate\fR For updates the primeUpdate() signal is emitted when the data browser enters update mode. After calling writeFields() call update() to update the record and connect to the beforeUpdate() signal to manipulate the user's data before the update takes place.
.TP
\fIdelete\fR For deletion the primeDelete() signal is emitted when the data browser enters deletion mode. After calling writeFields() call del() to delete the record and connect to the beforeDelete() signal, for example to record an audit of the deleted record.
This signal is emitted just before the cursor's edit buffer is deleted from the database. The \fIbuf\fR 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 \fIbuf\fR 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 \fIbuf\fR parameter points to the edit buffer being updated. You might connect to this signal to capture some auditing information about the update.
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 TQDataBrowser::Boundary.
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 TQSqlPropertyMap constructor for the default mappings of widgets to properties.
.SH "TQSql::Confirm TQDataBrowser::confirmCancel ( TQSql::Op m )\fC [virtual protected]\fR"
Protected virtual function which returns a confirmation for cancelling an edit mode \fIm\fR. 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 \fIm\fR. 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 cursor record was changed due to navigation. The \fImode\fR parameter is the edit that just took place, e.g. Insert, Update or Delete. See TQSqlCursor::Mode.
Performs a delete operation on the data browser's cursor. If there is no default cursor or no default form, nothing happens.
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Otherwise, the following happens:
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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.
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.
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If the browser is already positioned on the first record nothing happens.
This signal is emitted whenever the position of the cursor changes. The \fIavailable\fR parameter indicates whether or not the first record in the default cursor is available.
Performs an insert operation on the data browser's cursor. If there is no default cursor or no default form, nothing happens.
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If auto-editing is on (see setAutoEdit()), the following happens:
.TP
If the browser is already actively inserting a record, the current form's data is inserted into the database.
.TP
If the browser is not inserting a record, but the current record was changed by the user, the record is updated in the database with the current form's data (i.e. with the changes).
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If there is an error handling any of the above auto-edit actions, handleError() is called and no insert or update is performed.
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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 successfull, the cursor is refreshed and relocated to the newly inserted record, the cursorChanged() signal is emitted, and TRUE is returned.
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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.
.PP
If the browser is already positioned on the last record nothing happens.
This signal is emitted whenever the position of the cursor changes. The \fIavailable\fR 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.
.PP
If the browser is positioned on the last record nothing happens.
This signal is emitted whenever the position of the cursor changes. The \fIavailable\fR 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.
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If the browser is positioned on the first record nothing happens.
This signal is emitted whenever the position of the cursor changes. The \fIavailable\fR 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 \fIbuf\fR parameter points to the record buffer being deleted. (Note that TQSqlCursor::primeDelete() is \fInot\fR 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.
This signal is emitted when the data browser enters insertion mode. The \fIbuf\fR 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 TQSqlCursor::primeInsert() is \fInot\fR called on the default cursor, as this would corrupt values in the form.)
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 \fIbuf\fR parameter points to the record buffer being updated. (Note that TQSqlCursor::primeUpdate() is \fInot\fR 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.
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.
Moves the default cursor to the record specified by the index \fIi\fR and refreshes the default form to display this record. If there is no default form or no default cursor, nothing happens. If \fIrelative\fR 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.
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If the browser is already positioned on the desired record nothing happens.
Sets the browser's default form to \fIform\fR. The cursor and all navigation and data manipulation functions that the browser provides become available to the \fIform\fR.
Sets the default cursor used by the data browser to \fIcursor\fR. If \fIautoDelete\fR is TRUE (the default is FALSE), the data browser takes ownership of the \fIcursor\fR pointer, which will be deleted when the browser is destroyed, or when setSqlCursor() is called again. To activate the \fIcursor\fR use refresh(). The cursor's edit buffer is used in the default form to browse and edit records.
Performs an update operation on the data browser's cursor.
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If there is no default cursor or no default form, nothing happens. Otherwise, the following happens:
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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.
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 successfull, the cursor is refreshed and relocated to the updated record, the cursorChanged() signal is emitted, and TRUE is returned.
Writes the form's data to the default cursor's edit buffer. If there is no default cursor or no default form, nothing happens.
.SS "Property Documentation"
.SH "bool autoEdit"
This property holds whether the browser automatically applies edits.
.PP
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:
.TP
the insert or update is is performed -- this occurs if autoEdit is TRUE
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the insert or update is discarded -- this occurs if autoEdit is FALSE
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Set this property's value with setAutoEdit() and get this property's value with autoEdit().
.SH "bool boundaryChecking"
This property holds whether boundary checking is active.
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When boundary checking is active (the default), signals are emitted indicating the current position of the default cursor.
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See also boundary().
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Set this property's value with setBoundaryChecking() and get this property's value with boundaryChecking().
.SH "bool confirmCancels"
This property holds whether the browser confirms cancel operations.
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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.
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See also confirmEdits and confirmCancel().
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Set this property's value with setConfirmCancels() and get this property's value with confirmCancels().
.SH "bool confirmDelete"
This property holds whether the browser confirms deletions.
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If this property is TRUE, the browser confirms deletions, otherwise deletions happen immediately.
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See also confirmCancels, confirmEdits, confirmUpdate, confirmInsert, and confirmEdit().
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Set this property's value with setConfirmDelete() and get this property's value with confirmDelete().
.SH "bool confirmEdits"
This property holds whether the browser confirms edits.
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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,
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See also confirmEdit(), confirmCancels, confirmInsert, confirmUpdate, and confirmDelete.
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Set this property's value with setConfirmEdits() and get this property's value with confirmEdits().
.SH "bool confirmInsert"
This property holds whether the data browser confirms insertions.
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If this property is TRUE, the browser confirms insertions, otherwise insertions happen immediately.
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See also confirmCancels, confirmEdits, confirmUpdate, confirmDelete, and confirmEdit().
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Set this property's value with setConfirmInsert() and get this property's value with confirmInsert().
.SH "bool confirmUpdate"
This property holds whether the browser confirms updates.
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If this property is TRUE, the browser confirms updates, otherwise updates happen immediately.
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See also confirmCancels, confirmEdits, confirmInsert, confirmDelete, and confirmEdit().
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Set this property's value with setConfirmUpdate() and get this property's value with confirmUpdate().
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.
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There is no default filter.
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See also sort.
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Set this property's value with setFilter() and get this property's value with filter().
.SH "bool readOnly"
This property holds whether the browser is read-only.
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The default is FALSE, i.e. data can be edited. If the data browser is read-only, no database edits will be allowed.
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Set this property's value with setReadOnly() and get this property's value with isReadOnly().
.SH "QStringList sort"
This property holds the data browser's sort.
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The data browser's sort affects the order in which records are viewed in the browser. Call refresh() to apply the new sort.
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When retrieving the sort property, a string list is returned in the form 'fieldname order', e.g. 'id ASC', 'surname DESC'.
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There is no default sort.
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Note that if you want to iterate over the list, you should iterate over a copy, e.g.
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.nf
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QStringList list = myDataBrowser.sort();
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QStringList::Iterator it = list.begin();
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while( it != list.end() ) {
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myProcessing( *it );
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++it;
.br
}
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.fi
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Set this property's value with setSort() and get this property's value with sort().
