Interface nsIKeyValueDatabaseType

Clear all the key/value pairs from the database.

Remove the key/value pair with the given key from the database.

If the given key doesn't exist in the database, this operation doesn't fail; or rather, it fails silently, calling the resolve() method of its callback rather than reject(). If you want to know whether or not a key exists when deleting it, call the has() method first.

Enumerate key/value pairs, starting with the first key equal to or greater than the "from" key (inclusive) and ending with the last key less than the "to" key (exclusive) sorted lexicographically.

If either key is omitted, the range extends to the first and/or last key in the database.

Retrieve the value of the specified key from the database.

If the key/value pair doesn't exist in the database, and you specify a default value, then the default value will be returned. Otherwise, the callback's resolve() method will be called with a variant of type VTYPE_EMPTY, which translates to the JS null value.

Determine whether or not the key exists in the database.

Write the specified key/value pair to the database.

Write multiple key/value pairs to the database.

It supports two types of write:

• Put a key/value pair into the database. It takes a nsIKeyValuePair where its key and value follow the same types as the put() method.
• Delete a key/value pair from database. It takes a nsIkeyValuePair where its value property must be null or undefined.

This features the "all-or-nothing" semantics, i.e. if any error occurs during the call, it will rollback the previous writes and terminate the call. In addition, writeMany should be more efficient than calling "put" or "delete" for every single key/value pair since it does all the writes in a single transaction.

Note:

• If there are multiple values with the same key in the specified pairs, only the last value will be stored in the database.
• Deleting a key that is not in the database will be silently ignored.
• If the same key gets put and deleted for multiple times, the final state of that key is subject to the ordering of the put(s) and delete(s).