Cursor

Object Hierarchy:

Description:

[ CCode ( type_id = "tracker_sparql_cursor_get_type ()" ) ]
[ GIR ( name = "SparqlCursor" ) ]
public abstract class Cursor : Object

`TrackerSparqlCursor` provides the methods to iterate the results of a SPARQL query.

Cursors are obtained through e.g. [method@SparqlStatement.execute] or [method@SparqlConnection.query] after the SPARQL query has been executed.

When created, a cursor does not point to any element, [method@SparqlCursor.next] is necessary to iterate one by one to the first (and following) results. When the cursor iterated across all rows in the result set, [method@SparqlCursor.next] will return false with no error set.

On each row, it is possible to extract the result values through the [method@SparqlCursor.get_integer], [method@SparqlCursor.get_string], etc... family of methods. The column index of those functions starts at 0. The number of columns is dependent on the SPARQL query issued, but may be checked at runtime through the [method@SparqlCursor.get_n_columns] method.

After a cursor is iterated, it is recommended to call [method@SparqlCursor.close] explicitly to free up resources for other users of the same [class@SparqlConnection], this is especially important in garbage collected languages. These resources will be also implicitly freed on cursor object finalization.

It is possible to use a given `TrackerSparqlCursor` in other threads than the one it was created from. It must be however used from just one thread at any given time.

Namespace: Tracker.Sparql

Package: tracker-sparql-3.0

Content:

Properties:

public Connection connection { get; construct; }
The [class@SparqlConnection] used to retrieve the results.
public int n_columns { get; }
Number of columns available in the result set.

Creation methods:

protected Cursor ()

Methods:

public void close ()
Closes the cursor.
public bool get_boolean (int column)
Retrieve a boolean for the current row in column.
public unowned Connection get_connection ()
Returns the [class@SparqlConnection] associated with this `TrackerSparqlCursor`.
public DateTime? get_datetime (int column)
Retrieves a [type@GLib.
public double get_double (int column)
Retrieve a double for the current row in column.
public int64 get_integer (int column)
Retrieve an integer for the current row in column.
public unowned string? get_langstring (int column, out string langtag, out long length)
Retrieves a string representation of the data in the current row in column.
public int get_n_columns ()
Retrieves the number of columns available in the result set.
public unowned string? get_string (int column, out long length = null)
Retrieves a string representation of the data in the current row in column.
public ValueType get_value_type (int column)
Returns the data type bound to the current row and the given column.
public unowned string? get_variable_name (int column)
Retrieves the name of the given column.
public bool is_bound (int column)
Returns whether the given column has a bound value in the current row.
public bool next (Cancellable? cancellable = null) throws Error
Iterates the cursor to the next result.
public async bool next_async (Cancellable? cancellable = null) throws Error
Iterates the cursor asyncronously to the next result.
public void rewind ()
Resets the iterator to point back to the first result.

Inherited Members:

All known members inherited from class GLib.Object