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The MessageField Class

The MessageField class is used to define messages for efficient transmission across network or process space. Messages are defined using field classes .

MessageField is provided by the protorpc.messages module.

1. MessageField()
2. Class Property
   • type
   • message_type

Constructor

The constructor of the MessageField class is defined as follows:

class MessageField ( message_type , number , [ required = False | repeated

Class Property

The MessageField class provides the following properties:

type

The Python type used for values of this field. For example, in the case of DateTimeField , type is datetime.datetime . For user defined MessageFields, type is the specified Message type.

message_type

The underlying message type used for serialization. Specifically this is the type that you can store on an instance of a Message class. For example, for DateTimeField , the type will be message_types.DateTimeMessage . For normal message fields it will be the protorpc message subclass. For example:

class Sub(messages.Message):
  x = messages.IntegerField(1)

class M(messages.Message):
  sub = messages.MessageField(Sub, 1)
  dt = message_types.DateTimeField(2)

print 'M.sub.type         =', M.sub.type
print 'M.sub.message_type =', M.sub.message_type
print 'M.dt.type          =', M.dt.type
print 'M.dt.message_type  =', M.dt.message_type


=== output ===
M.sub.type                 = <class '__main__.Sub>
M.sub.message_type = <class '__main__.Sub'>
M.dt.type                   = <type 'datetime.datetime'>
M.dt.message_type   = <class 'protorpc.message_types.DateTimeMessage'>