RejectedSoftware Forums

On Tue, 21 Oct 2014 08:26:28 GMT, Jack Applegame wrote:

The current implementation of the serialization framework always serializes all serializable fields.

I think there must be a way to specify (runtime) that a particular field must not be serialized.

For example, seriаlizer skips the field is marked as optional if its value is the default value. Or if the field is marked as optional and has bool skipSerialization() method and it returns true.

What do you think about this?

There's @ignore for this: http://vibed.org/api/vibe.data.serialization/ignore

On Mon, 22 Dec 2014 10:22:35 GMT, Jack Applegame wrote:

On Sun, 21 Dec 2014 19:59:50 GMT, Mathias LANG wrote:

There's @ignore for this: http://vibed.org/api/vibe.data.serialization/ignore
I'm talking about run time not compile time.

Okay. I can't see why you would use it (looks like lack of SoC), could you provide an use case ?
Anyway, I can imagine something like this fitting into Vibe.d:

struct MyStruct {
  @optional(canSerialize) int value;
  bool canSerialize(int value) { return value != 42; }
}

Here, 'MyStruct.value' will only be serialized if the return value from canSerialize (which can be either a member or a free function) is true. Would that do ?

On Mon, 22 Dec 2014 12:23:59 GMT, Jack Applegame wrote:

On Mon, 22 Dec 2014 10:41:10 GMT, Mathias LANG wrote:

Okay. I can't see why you would use it (looks like lack of SoC), could you provide an use case ?
I just don't want to serialize data with default values. This is useless overhead (extra network traffic and CPU load).

Okay. I can't see why you would use it (looks like lack of SoC), could you provide an use case ?
Anyway, I can imagine something like this fitting into Vibe.d:

struct MyStruct {
  @optional(canSerialize) int value;
  bool canSerialize(int value) { return value != 42; }
}

Here, 'MyStruct.value' will only be serialized if the return value from canSerialize (which can be either a member or a free function) is true. Would that do ?
Good idea. Like attributes for web interfaces:

struct MyStruct {
    bool canSerialize() { return this.value != 42; }
    @optional!canSerialize int value = 42;
}

Does vibe.d support that approach?

Not currently. It can be worked around somewhat by providing a custom toRepresentation method:

struct MyStruct {
    int value = 42;
    Json[string] toRepresentation() {
        Json[string] ret;
        if (value != 42) ret["value"] = value;
        return ret;
    }
    static MyStruct fromRepresentation(Json[string] j)
    {
        MyStruct ret;
        if (auto pv = "value" in j)
            ret.value = pv.get!int;
        return ret;
    }
}

As far as I understand I need to implement serialization for whole object in this case?

Instead of the @optional!canSerialize another (or an additional) possibility would be to handle @optional Nullable!int value; in that way.

Doesn't work for string[] for example.

Of course, skipping the value if it equals .init, like suggested in the OP, is also a possibility.

Any further opinions or use cases?

REST server accept only one of two fields and reject request if you send both for example.