Conditional transformer

[Ricardo Brandão]

Hi,

I have the following transformer:

public class ResultTranslationTransformer : AbstractTransformerCreationTask<Result>

{
    public const string LANGUAGE_PARAMETER_KEY = "LanguageName";

    public InterfaceTranslationTransformer()
    {
        TransformResults = results =>
            from result in results
            let translation = LoadDocument<ResultTranslation>(result.Id + "/" + Parameter(LANGUAGE_PARAMETER_KEY))
            select new
            {
                result.Id,

                Name = translation != null ? translation.Name : result.Name,
                Language = translation != null ? translation.Language : result.Language,
            };
    }

}

However I want to conditionally apply this transformer to the results with the following condition:

if(result.Language != Parameter(LANGUAGE_PARAMETER_KEY))
{
    // apply transformer
}

Otherwise I want to return the result without performing any transformation.

Any ideas?

Thanks in advance.

P.S. I have taken a look at this discussion but it seems that no proper solution has been provided.

[Michael Yarichuk]

Can you share more info about what do you want to achieve?

In general, why not apply transformer on a query that is already filtered by your condition?

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[Ricardo Brandão]

Sure.

I have an application where users can create content in different languages. For that, users are able to create content in a specific language and then that content can be translated into different languages.

For that I have the following entities:

public class Result {

    public string Id {get;set;}
    public string Name {get;set;}
    public string Language {get;set;}
}

public class ResultTranslation {

   public string Id {get;set;}
    public string ResultId {get;set;}
    public string Name {get;set;}
    public string Language {get;set;}
}

What I need/want to do is to load some content in a requested language like this:

var results = DocumentSession

                .Load<ResultTranslationTransformer, Result>(_ids, configuration =>

                    configuration.AddTransformerParameter(ResultTranslationTransformer.LANGUAGE_PARAMETER_KEY, _languageName));

in order to retrieve the results in the requested language.

Since the content can be created in different languages, the transformer needs to check if it is necessary to "translate" the result or if we are good to go.

Thanks

[Chris Marisic]

Don't do that. Databases aren't meant for executing application/business code.

Use your application to properly encode your data then persist completed documents.

[Ricardo Brandão]

My data is not business aware. However I don't want to load things I don't need/have and that is why I want to transform the results conditionally when loading the data from the database. 

Furthermore I really don't want to keep one file with all the translations (for a lot of reasons but mainly performance by issues) and that is why I have separate documents for translations.

[Chris Marisic]

UserContent/1 

{

locale: en-us

content: "foo foo foo"

}

then when you need DE-GB or whatever is a valid locale

var translated = session.Get("UserContent/1/DE-GB") 

if(translated = null)

{

 translated = Translate("DE-GB", session.Get("UserContent/1"))

translated.Id = "UserContent/1/DE-GB"

session.Store(translated)

session.SaveChanges();

}

return translated

[Oren Eini (Ayende Rahien)]

public class ResultTranslationTransformer : AbstractTransformerCreationTask<Result>

{
    public const string LANGUAGE_PARAMETER_KEY = "LanguageName";

    public InterfaceTranslationTransformer()
    {
        TransformResults = results =>
            from result in results
            let translation = LoadDocument<ResultTranslation>(result.Id + "/" + Parameter(LANGUAGE_PARAMETER_KEY))

            select  Parameter("LangKey") != "en-US" ?  new
            {
                result.Id,

                Name = translation != null ? translation.Name : result.Name,
                Language = translation != null ? translation.Language : result.Language,

            } : result;
    }

}

Hibernating Rhinos Ltd  

Oren Eini l CEO l Mobile: + 972-52-548-6969

Office: +972-4-622-7811 l Fax: +972-153-4-622-7811

 

On Tue, Jul 21, 2015 at 4:43 PM, Ricardo Brandão <ricardo...@welisten.eu> wrote:

--

[Ricardo Brandão]

Hi Chris,

We already had a solution similar to that but we were not very happy with it because the code was getting too complicated. And since this is going to be used in many places we decided to find a better solution.

[Ricardo Brandão]

Hi Oren,

That's it and you kept it really simple! 

Thanks.

[Ricardo Brandão]

One quick question Oren,

What's the impact of loading the translation? Because with you solution we still always load a translation.

[Oren Eini (Ayende Rahien)]

I don't understand the question. What do you mean?

[Ricardo Brandão]

If you take a look at:

 from result in results
            let translation = LoadDocument<ResultTranslation>(result.Id + "/" + Parameter(LANGUAGE_PARAMETER_KEY))

            select  Parameter("LangKey") != "en-US" ?  new

You'll see that we will load the translation first. However, if we already have the result in the requested language, we don't need to do this load (actually, it will return null).

My question is that if this affects the performance.

[Oren Eini (Ayende Rahien)]

Yes, probably.

You can move this into the other section, though.

[Chris Marisic]

Embedding this in the database is definitely not a better solution, it is a radically worse solution.