Add a last updated timestamp on all my mongo collections

[bg]

Hi all,

I would like to create a "last updated" timstamp across all my collections.

My model classes look like

class User extends MongoRecord[User] with MongoId[User] {

....

object User extends User with MongoMetaRecord[User] {

....

Any suggestions, or examples on a good way to implement this? Looking for every collection to get a field which gets poptulated with the currect time whenever a update is performed.

Thanks

[Richard Dallaway]

This was originally written for Squeryl, but as the example indicates, it'll work for Mongo too:

http://cookbook.liftweb.net/Create+and+update+trait+for+record.html

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[bg]

Perfect - thank you

[bg]

I'm having some trouble with the 

def  consumerCallbacks = Seq( beforeUpdate[Consumer] call {_.onUpdate}) 

Do I need to do something along the lines of the below to my User class?

class User extends MongoRecord[User] with MongoId[User] with LifecycleCallbacks { 

that give a compiler error - so I guess its not quite that!

illegal inheritance;

[error]  self-type com.blendology.sojo_database.model.User does not conform to net.liftweb.record.LifecycleCallbacks's selftype net.liftweb.record.LifecycleCallbacks with net.liftweb.record.BaseField

[error] class User extends MongoRecord[User] with MongoId[User] with CreatedUpdated[User] with LifecycleCallbacks {

And then would that line (or something similar) go in the User class?

Thanks

[Carlos Montemuiño]

Hi, I think next post might help you: http://bit.ly/X3TTLe

[bg]

My understanding of that post is LifecycleCallbacks are not for Records 

If so - is there anything else I can hook onto in order to update the "last updated" timestamp on each transaction?

[Richard Dallaway]

Hello

The cookbook example is confusing: it is Squeryl specific (and possibly only for 2.5 too), even though it gives a record that is Mongo-based. I'll re-work it to clear up that confusion.

However, that doesn't help you. 

For Mongo, although the updated and created fields will be there when you add a record, I can't currently see a way to automatically trigger the update.

Richard

--

[bg]

there  is a package net.liftweb.record.LifecycleCallbacks 

So I guess LifecycleCallbacks does exist within the Record world, but is it the case that MongoRecord doesn't use them?

On Wednesday, October 31, 2012 9:02:26 PM UTC, bg wrote:

[Tim Nelson]

Hi bg,

MongoRecord does use the LifecycleCallbacks. However, currently they only work for save and delete. I will add the update callbacks to the update function.

Here's a field that should work for you with the save function:

object updatedAt extends DateTimeField(this) with LifecycleCallbacks {

  override def beforeSave() {

    super.beforeSave

    this.set(Calendar.getInstance)

  }

}

Tim

[Tim Nelson]

Hi again,

You probably wanted a trait, so here's one that works. I will probably be adding this to Record at some point.

trait Updated[T <: Updated[T]] extends Record[T] {

  self: T =>

  /**

   * The updatedAt field.  You can change the behavior of this

   * field:

   * <pre name="code" class="scala">

   * override lazy val updatedAt = new MyUpdatedAt(this) {

   *   override def dbColumnName = "i_eat_time_for_breakfast"

   * }

   * </pre>

   */

  lazy val updatedAt: MyUpdatedAt = new MyUpdatedAt(this)

  protected class MyUpdatedAt(obj: T) extends DateTimeField(obj.asInstanceOf[T]) with LifecycleCallbacks {

    override def beforeSave() {

      super.beforeSave

      this.set(Calendar.getInstance)

    }

  }

}

Tim

[bg]

Brilliant - thank you very much, working on the create and saves.