# IDataSource.GetList()

Description:

The `GetList` method retrieves an iterable list of entries from the log event database. The database contains two types of entries, log entries (all entries) and recent log entries (a subset of all log entries).

This method can be called both synchronously and asynchronously.

Syntax:

For synchronous calls:

    result = so.IDataSource.GetList(criteria);

For asynchronous calls:

    result = so.IDataSource.GetList(criteria, callback);

Arguments:

- `criteria`:

  This is an object that specifies what information is returned from the log event database. For more information about the object properties and how to define them, see section Criteria for retrieving log events.

- `callback`:

  The `callback` argument is the name of the method that is executed when an asynchronous `GetList` call has results or status information to return. You must define this method separately. Follow the instructions in section Defining the callback handler for an asynchronous method to define the `callback` method.

  This argument is used only with an asynchronous `GetList` call.

Return value:

If synchronous, the `GetList` method returns an object that contains the requested log event information, an error code, and an error message.

Table: Return value properties for a synchronous GetList
Property | Description | Value
--- | --- | ---
`result.ReturnValue` | This is an iterator that contains the requested log event information. | See Returned log event information.
`result.ErrorCode` | This is a number that specifies a predefined error code. | See Service API error codes .
`result.ErrorMessage` | This is a text string that describes the error. | See Logging Service API error messages.

If asynchronous, the `GetList` method returns an object that contains the initial return value from the asynchronous call that it started (see the following table). The actual information is returned by the `callback` method in the `ReturnValue` property of its result object. The returned information is described in section Returned log event information.

Table: Return value properties for an asynchronous GetList
Property | Description | Value
--- | --- | ---
`result.TransactionID` | This is a number used as an identification to match transactions started with the asynchronous `GetList` call to one or more calls it generates to `callback`. This property is only valid for asynchronous calls. |
`result.ErrorCode` | This is a number that specifies a predefined error code. | See Service API error codes.
`result.ErrorMessage` | This is a text string that describes the error. | See Logging Service API error messages.

Remarks:

To access information about individual log events, iterate through the list of objects contained in `result.ReturnValue`.

Example code:

For the complete source of a sample widget that demonstrates how to use this Service API, see the full example.