The Transcoder interface may be used to provide custom value and key formats. Among the uses of the transcoder class, one may:
Implement compatibility with other client libraries
formatoption in the operations correspond to a flag value which is stored in the server as meta data along with the key. These flags are utilized by client libraries to determine how to interpret the value on the server (which is just a set of bytes) into a more complex and user-friendly type in the native client language. Some clients may have different ideas about which flags mean which value format, and some clients may use formats which are specific to that platform (for example,
FMT_PICKLEwhich is typically only native to Python objects). One may implement a custom transcoder class which understands a wider variety of types and flags
If storing large values, it may be handy to compress them before storing them on the server. This provides for lower network overhead and storage space on the server, at the expense of the computational overhead of compressing and decompressing objects. One may add extra flags to indicate a value has been compressed, and with which format.
Automatic conversion of different value types into custom classes
The built-in transcoder only uses native Python types. One may wish to interpret values as belong to user-defined classes.
Transcoder class is implemented in C for efficiency, but
a pure-python implementation is available as the
Typically one would subclass the
Transcoder class, and
implement the needed methods, allowing for high efficient built-in
methods to perform the un-needed operations.
Note that the
Client does not
Transcoder object by default (however it internally uses
the same routines that the C-implemented
Transcoder does). Thus,
if no custom transcoding is needed, it is more efficient to set the
is the default.
- class couchbase_core.transcoder.Transcoder¶