Re: [ceylon-users] Re: DeserializationContex recreation of Sequence/Stream/List

[Tom Bentley]

Hi Wojciech,

I can't really tell from this which bits of the documentation need improving and how. Would you be able to explain the particular things you struggled to understand, and why?

Or even better a pull request updating the documentation would be great.

Many thanks,

Tom

On 16 September 2016 at 21:01, Wojciech Potiopa <wojciech...@gmail.com> wrote:

Man... after rough source inspection i finally used DeserializationContext<Element>.element(...) method. This is soo intuitive and sooooo undocumented. For further reference DeserializationContext<Element>.element(...)  method can be used for List<Element> reconstruction. But some prerequisites must be fulfilled.
Prerequisites:

1) The attribute being declared as List<Element> must be registered with DeserializationContext<Element>.instance() method.
Parameters:
a) InstanceId- instance id which will be used for DeserializationContext<Element>.attribute() method for that specific field being declared as List<Element>;
b) `Array<Element>`

2) The attribute "size" of the Arrray<Element> for field  being declared as List<Element> must be registered with DeserializationContexext<Element>.attribute() method.
Parameters:
a) InstanceId- instance id which will be used for DeserializationContext<Element>.instance() method for that specific field being declared as List<Element> (the same as step before);
b) `Array<Element>.size`.declaration
c) attributeValueId- id of attribute which will be used for attaching value of size for Array<Element>.size attribute.

3) The attribute "size" of the Array<Element> must be set to value coresponding with  DeserializationContexext<Element>.element() calls by calling DeserializationContexext<Element>.instanceValue() .
Parameters:
a) instanceId - attributeValueId from last step
b) size of List<Element> / Array<Element> which attribute being reconstructed.

4) All content must be recreated with two methods call:
- DeserializationContexext<Element>.instanceValue()
Parameters:
a) InstanceId - unique id of content value (Element) - (referenced further as "unique")
b) instanceValue - value of content (Element)

- DeserializationContexext<Element>.element()
Parameters:
a) InstanceId- the same id as in point - 1,2
b) index of element in Array<Element>/List<Element>
c) the "unique" identifier used before

The whole test looks like this:

shared serializable class TestDataList(shared List<String> objs){}

shared test void listAutomaticRecreation(){
    DeserializationContext<String> context = deserialization<String>();
    context.instance(`TestDataList`.declaration.name, `TestDataList`);
    context.attribute(`TestDataList`.declaration.name, `TestDataList.objs`.declaration, `TestDataList.objs`.declaration.name);
    String[] sequence=["abc","fed"];
    context.instance(`TestDataList.objs`.declaration.name, `Array<String>`);
    context.attribute(`TestDataList.objs`.declaration.name, `Array<String>.size`.declaration, `Array<String>.size`.declaration.name);
    context.instanceValue(`Array<String>.size`.declaration.name, sequence.size);
    for(Integer->String a in sequence.indexed){
        context.instanceValue(a.key.string, a.item);
        context.element(`TestDataList.objs`.declaration.name, a.key, a.key.string);    
    }
   
    TestDataList reconstruct = context.reconstruct<TestDataList>(`TestDataList`.declaration.name);
    assert(sequence.every((String element) => reconstruct.objs.contains(element)));
   
}

Cheers
Wojciech.

On Monday, 12 September 2016 13:00:38 UTC+2, Wojciech Potiopa wrote:

I was able to recreate each type of collection by manually providing instanceValue with constructed Sequence/Stream/List
example:

import ceylon.test {
    test
}
import ceylon.language.serialization {
    deserialization,
    DeserializationContext
}


shared serializable class TestDataSequence(shared String[] objs){}

shared test void  sequenceManualRecreation(){
    DeserializationContext<String> context = deserialization<String>();
    context.instance(`TestDataSequence`.declaration.name, `TestDataSequence`);
    context.attribute(`TestDataSequence`.declaration.name, `TestDataSequence.objs`.declaration, `TestDataSequence.objs`.declaration.name);
    String[] objs=["abc","fed"];
    context.instanceValue(`TestDataSequence.objs`.declaration.name, objs);
    TestDataSequence reconstruct = context.reconstruct<TestDataSequence>(`TestDataSequence`.declaration.name);
    assert(reconstruct.objs==objs);
}

is it possible that DeserializationContex would take care with recreation of Sequence/Stream/List for me ? There is DeserializationContext.element method but I'm not able to correctly use it.

shared test void sequenceAutomaticRecreation(){
    DeserializationContext<String> context = deserialization<String>();
    context.instance(`TestDataSequence`.declaration.name, `TestDataSequence`);
    context.attribute(`TestDataSequence`.declaration.name, `TestDataSequence.objs`.declaration, `TestDataSequence.objs`.declaration.name);
    String[] objs=["abc","fed"];
    for(Integer->String obj in objs.indexed){
        context.element(`TestDataSequence.objs`.declaration.name, obj.key, `TestDataSequence.objs`.declaration.name+obj.key.string);
        context.instanceValue(`TestDataSequence.objs`.declaration.name+obj.key.string, obj.item);
    }
    TestDataSequence reconstruct = context.reconstruct<TestDataSequence>(`TestDataSequence`.declaration.name);
    assert(reconstruct.objs==objs);
}

Test throws:
ceylon.language.serialization.DeserializationException " no class specified for instance with id objs"

Looking at DeserializationContext.element method it seems as it works like DeserializationContext.attribute so it should be ok ;) How to make it work, the best would be if it would also allow deserialization of collections and streams ? Should i always manually Sequence/Stream/List like in first test ? If so what for is DeserializationContext.element  method ?

Cheers
Wojciech

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[Tom Bentley]

Hi Wojciech,

Posting them here is fine.

If it helps to see the API used in context have a look at a serialization library I've written (https://github.com/tombentley/alabama). I will be publishing this on the herd very soon.

Cheers,

Tom

On 20 September 2016 at 21:49, Wojciech Potiopa <wojciech...@gmail.com> wrote:

Hi Tom.
I'm not sure right now if i fully understand application of DeserializationContext methods - so I wouldn't provide you proper documentation update. I can post my doubts and struggles here or via e-mail if you wish - the discussion here may be better option for further generations :). So if you do not mind i will post them here in meantime.

Thank You,
Wojciech

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