Rails: Set default model values

[mwmitchell]

Hi,

I have a model called Product. The Product has date_modified and date_created fields. I'd like to set the value to now() (mysql). I thought it'd be as simple as setting the value in the controller.create method:

@product = Product.new(params[roduct])
@product.date_created = 'now()'

The 'now()' value needs to be un-escaped: values(now(), 'string', etc..)

But that doesn't do it. What gives? Also, is there a way to do this in the model?

-matt

[DougBTX]

The easy way to get this behaviour is to take advantage of the Timestamp module and rename your column from date_created to created_on.

The manual way to do it, would be more like this:

@product = Product.new(params[:product])
@product.date_created = Time.now

You can see the source for the created_on feature here, and you can see it does basically the same thing as the code above.

Edit: if you really want to use 'now()', you could probably do it with connection.execute(sql),though it isn't sometihng I've had to use before.

hth,
Douglas

[xmitchx]

I concur. Its probably not a very smart idea to use direct SQL since rails will handle escaping the values for you. Using the Time module you can create timestamps that work with SQL databases

[mwmitchell]

OK cool. But just for my own knowledge, how do you set a models values directly? Without quoting?

Thanks a lot! It's working great using Time.now

-matt

[Luke Redpath]

If you name your columns "created_on" and "modified_on" then Rails will handle this for you automatically.

[DougBTX]

OK cool. But just for my own knowledge, how do you set a models values directly? Without quoting?

From outside the model? Don't know, sorry.

From inside the model, write_attribute/read_attribute are useful, but everything in the attributes hash goes through attributes_with_quotes on create and update (called by my_model_object.save). That means you'll have to write the SQL yourself to get unquoted data in there.

Here's how Rails does update internally, you could base your code on that:

1435 	      def update
1436 	        connection.update(
1437 	          "UPDATE #{self.class.table_name} " +
1438 	          "SET #{quoted_comma_pair_list(connection, attributes_with_quotes(false))} " +
1439 	          "WHERE #{self.class.primary_key} = #{quote(id)}",
1440 	          "#{self.class.name} Update"
1441 	        )
1442 	      end

So you'd have something like:

def custom_update
  custom_sql_data = "... now() ..."
  connection.update(
    "UPDATE #{self.class.table_name} " +
    "SET #{custom_sql_data} " +
    "WHERE #{self.class.primary_key} = #{quote(id)}",
    "#{self.class.name} Update"
  )
end

And I think it should work. Just remember that you are going around most of ActiveRecord by doing that, so if you find yourself doing it regularly, you might want to use a different ORM, or just not bother with an ORM in the first place

Douglas

[mwmitchell]

Thanks! I'm going to go with the created_on and modified_on method. So simple.

-matt