Any contains an arbitrary serialized protocol buffer message along with a
URL that describes the type of the serialized message.
Protobuf library provides support to pack/unpack Any values in the form
of utility functions or additional generated methods of the Any type.
Example 1: Pack and unpack a message in C++.
Foo foo = ...;
Any any;
any.PackFrom(foo);
...
if (any.UnpackTo(&foo)) {
...
}
Example 2: Pack and unpack a message in Java.
Foo foo = ...;
Any any = Any.pack(foo);
...
if (any.is(Foo.class)) {
foo = any.unpack(Foo.class);
}
Example 3: Pack and unpack a message in Python.
foo = Foo(...)
any = Any()
any.Pack(foo)
...
if any.Is(Foo.DESCRIPTOR):
any.Unpack(foo)
...
Example 4: Pack and unpack a message in Go
foo := &pb.Foo{...}
any, err := ptypes.MarshalAny(foo)
...
foo := &pb.Foo{}
if err := ptypes.UnmarshalAny(any, foo); err != nil {
...
}
The pack methods provided by protobuf library will by default use
'type.googleapis.com/full.type.name' as the type URL and the unpack
methods only use the fully qualified type name after the last '/'
in the type URL, for example "foo.bar.com/x/y.z" will yield type
name "y.z".
JSON
The JSON representation of an Any value uses the regular
representation of the deserialized, embedded message, with an
additional field @type which contains the type URL. Example:
package google.profile;
message Person {
string first_name = 1;
string last_name = 2;
}
{
"@type": "type.googleapis.com/google.profile.Person",
"firstName": <string>,
"lastName": <string>
}
If the embedded message type is well-known and has a custom JSON
representation, that representation will be embedded adding a field
value which holds the custom JSON in addition to the @type
field. Example (for message [google.protobuf.Duration][]):
{
"@type": "type.googleapis.com/google.protobuf.Duration",
"value": "1.212s"
}