ContactETag Property

The ETag of the current contact in a Google Contacts feed.

Syntax

 gcontacts.getContactETag([callback])
 gcontacts.setContactETag( contactETag, [callback])

Default Value

""

Callback

The 'callback' parameter specifies a function which will be called when the operation completes (or an error is encountered). If the 'callback' parameter is not specified, then the method will block and will not return until the operation completes (or an error is encountered).

The callback for the getContactETag([callback]) method is defined as:

function(err, data){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'data' is the value returned by the method.

The callback for the setContactETag([callback]) method is defined as:

function(err){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'err' has 2 properties which hold detailed information:

err.code
err.message

Remarks

To ensure that the data sent to Google does not overwrite another client's changes, Google checks the ETag sent with the request against the ETag of the existing contact. If they do not match, this means the last change was made by a different client, and the "HTTP 412 Precondition Failed" status code is returned.

This property is used to obtain the ETag of the specified contact within a Google Contact feed and will be populated once ContactIndex is set.

This property is also used when retrieving, updating or deleting an entry. When ContactETag contains a non-empty string, an "If-None-Match" header will be sent with the entered value when QueryContacts is called. When DeleteContact or UpdateContact is called, an "If-Match" header will be sent with the entered value.

To bypass this verification process and process the update regardless of updates from other clients, set this configuration setting to "*".

This property is not available at design time.

Data Type

String