[2.0] Null value in any field that is not the primary key (@Id), refer to sample project zentasks

[Priyo]

Hi guys,

I am playing around with Play and have noticed a behaviour that occurs in my application and the sample zentasks, which leads me to believe this is more than a mistake by myself. In zentasks you have the item.scala.html, there is this line of code.

<span class="assignedTo">@task.assignedTo.emal</span>

The tasks object encapsulates a User object which is called assignedTo. In that particular line of code, the email field which is of type @Id (primary key) is returned normally as you would expect. However when i want to retrieve a different field for example, name which is not a primary key, the value returned is null. Now i checked using Java in the controller class if the same is true, however using the Logger, i noticed the returned value is a String with the correct name associated with that user and the email. My question is why can't i access the name field, the reason why i have brought the primary key to your attention is because the task object has another object encapsulated within it, the project object. The same is true for that object too. I can only access the primary key but not any other field.

Kind Regards,
Priyo

[Guillaume Bort]

This issue has been discussed before. It's because the other fields were not fetched during the query. Then Ebean (like hibernate and other magic libraries) use bytecode manipulation to issue a select query in field access. 

Unfortunately this magic is not available when you access a direct field from within scala (because the scala code itself would be modified)

So there are 2 options:

- Rely on magic and use plain old getter and setter to enable it. 

- Don't use lazy loading and fetch everything during the query. 

For my point of view, having lazy loading not working from template is a feature. It avoid to have the template rendering accidentely issuing tens of db queries as it is often the case in java applications. 

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[Priyo]

Thank you Gullaume,

I didn't quite know what to search for apart from the symptom itself, hence i had to resort to a posting. Thank you for clearing this up.

Regards.

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