Tag "models" tricks

Often a foreign key needs to be set to NULL. On my projects I often use a drop down for this, and using an empty string as an option value does not work. I (hopefully) improved on this method[1] to set null values only on certain fields when saving a model. The original idea is from stackoverflow[2]. This method uses a BaseModel from which all models inherit. Any FK fields should be added to the model's $nullable property (an array). The work is done by the BaseModel. [1] http://laravelsnippets.com/snippets/set-fields-to-null-instead-of-empty-value-to-avoid-problems-with-nullable-foreign-keys [2] http://stackoverflow.com/questions/17452923/empty-string-instead-of-null-values-eloquent/19101473#19101473

Sometimes you'll need to put custom fields in your dropdown field, like user's firstname and name. That's how you can do it.

Laravel's docs suggest to override the Model's getDates() methods when adding your own date fields. http://laravel.com/docs/4.2/eloquent#date-mutators To keep the default created_at, updated_at and deleted_at date fields, these must also be returned by the method, giving you at least 4 elements to the array. An easier (or at least, tidier) way is to set the protected $dates property with your own fields. These are merged with the defaults.

Since Eloquent doesn't do a real join when using "with" this will add a simple join method without having to worry about the join columns since it's all stored with the models anyway. It will also select all the columns from the joined table with an added prefix of the table name.

This scope function applies a callback to the elements of a given query collection.

You can chain eager loading to avoid N+1 problem. Suppose you have 3 tables. customer[id, email], pos[id, serial_number] and restaurant[id, name, customer_id, pos_id] so restaurant table can act like a pivot table and it also have some value attribute. So now we can call customer from pos table via chaining eager loading.

Laravel has many choices for performing a query, sometimes it could be confusing, I hope this list help you to clear any doubts. If you know other way please show it in comments for add it.

I recently figured out that you can specify the columns that you want to select from an eager loaded relationship in Eloquent. I thought others might find this useful as I couldn't find much about this online!

I've used this technique to check if I have called any `->with()` or other relations loaded on a model. I had a need for this since I have a lot of methods that require relation data in order to generate an appended property on the model. For example, if I want to pull all of the recent Posts of an Author and I want to store it on the model as `posts_this_month`, I would need to have Posts relation loaded. I want to force myself to eager load that data before I try to access it, otherwise I could run into an n+1 problem.