I have a model "User", and each user has "Posts". Now there are different types of posts, like "TextPost", "VideoPost", etc.
I want to get all posts of a user like this:
$user->posts()->get()
This should return an array of objects with the correct class, so e.g. an array like this:
[App\VideoPost{}, App\TextPost{}]
I tried to use polymorphic relationships as described in the docs, but it doesn't work. Any ideas?
There isn't really a relationship type in Laravel for your specific use case. The easiest thing you can do in this case is create a separate hasMany relationship for each of your post types, and then write a function that returns a combination of all the results.
So you'd end up with something like this in your User class:
public function videoPosts()
{
return $this->hasMany(App\VideoPost::class);
}
public function textPosts()
{
return $this->hasMany(App\TextPost::class);
}
public function getPosts()
{
return $this->textPosts->concat($this->videoPosts);
}
You can then just keep chaining concat calls for every other post type you may want to add.
Related
I've inherited a Laravel 5 project at work and would like to know how I should check for the existence of a related model to avoid null exceptions.
BlockDate model
class BlockDate extends Model {
public function claims()
{
return $this->belongsToMany(User::class);
}
}
User model
class User extends Model {
public function blocks()
{
return $this->belongsToMany(BlockDate::class);
}
}
Pivot table
$table->unsignedInteger('user_id');
$table->foreign('user_id')->references('id')->on('users');
$table->unsignedInteger(block_date_id');
$table->foreign('block_date_id')->references('id')->on(block_dates);
Users can claim a range of dates for vacation requests. However, users may have no claims or dates may not have been claimed. I am currently using
if ($user->blocks->count() > 0) {
$dates = $user->blocks->sortByDesc('created_at');
// more logic here....
}
I do not like using count everywhere, is there a way to incorporate the check like:
// I don't know what hasClaimedDates might be
$dates = $user->hasClaimedDates()->blocks->sortByDesc('created_at');
You can use the actual relationship method instead of the magic accessor:
$sortedDates = $user->blocks()->latest()->get();
This will give you an empty collection if no relations are established, but it will not fail on the sorting.
Note: latest() is an equivalent for orderBy('created_at', 'desc') in this case.
By the way, if you use $user->blocks->count(), it will first load all related models into memory and then count on the relation. If you are going to use the related models afterwards, that is fine. But if you don't and you only count them, this is a waste of resources. In this case $user->blocks()->count() is way more performant as it executes a database query that only returns a single number. Take this into consideration especially where you have a lot of related models.
Laravel offers an optional helper method to guard against nulls:
// will return either a collection or null
$dates = optional($user->blocks)->sortByDesc('created_at');
If I have a model that needs to have a property that is an array of different models. Is there an eloquent method or way to handle this kind of problem?
eg.
I have a Feature model that needs a method that gets an array of objects that are from different models.
class Feature extends Model
{
public function getArrayOfDifferentObjects()
{
$array_of_objects=array();
???? ELOQUENT to get objects from different models ????
return $array_of_objects;
}
}
I have a feature_model_connections table with the following:
feature_id
featured_model_id
featured_model_type
The featured_model_type value would be a string denoting the model type.
The model_id would be a foreign key of the relevant model's table.
However I can't see how you would be able to use eloquent to return data for the getArrayOfDifferentObjects method in features model.
Any pointers would be much appreciated. Many thanks, J
What you are describing there, is basicly a Polymorphic Relations, which can handle these cases, and making fetching them easy, instead of i'm making a made up case, read the documentation, it is well written, under the section Polymorphic Relations. https://laravel.com/docs/5.1/eloquent-relationships#polymorphic-relations
Within your scope right now, you can do something like this.
public function getArrayOfDifferentObjects()
{
$objects = [];
$features = DB::table('feature_model_connections')
->select('feature_id', 'featured_model_id', 'featured_model_type')->get();
foreach($features as $feature)
{
$type = '\\App\\' . $feature->featured_model_type; //App is you app namespace
$model = $type::find($feature->featured_model_id);
if($model)
$objects[] = $model;
}
return $objects;
}
The basics of this, is you can define different types, with the app namespace seed, from there staticly call them, which will access the predefined type in your database table, then find the element and add it to the array. With that said, this is done as of the top of my head, no compile check, not ranned in Laravel, but it should pretty much get you the idea of what to do, with that said, if you can change your structure, go with the Polymorphic Relations, it is really awesome.
Now I get some model with all properties filled except one.
So I want to make a search in a database and see if there is some registry that matches all the properties values, in which case, get the last property value and keep it.
Now im doing a query wit query builder, giving it all where like this:
$query->Model::select()->where(field, $instance->field);
$query->where(field2, $instance->field2);
...
$query->get();
But I want to know if there some way to make a shortcut like...
$instance->get();
Yes you can do this by defining method in your model like this
class YourModel extends Model
{
public function getFiltered()
{
return Model::where('field1',$this->field1)->where('field2',$this->field2)->get();
}
}
And you can access it like this:
$instance->getFiltered();
You cannot keep function name 'get' because It's already being used in Model which is being extended. But you can change from getFiltered to anything which is not used. Like If the Model was User and the function getFiltered gives user's comments then It can be comments.
My Association model looks like this (irrelevant code redacted):
class Association extends Model
{
public function members() {
return $this->hasMany('App\Member');
}
}
My Member model looks like this:
class Member extends Model
{
public function scopeActive($query) {
return $query->where('membership_ended_at', Null);
}
public function scopeInactive($query) {
return $query->whereNotNull('membership_ended_at');
}
}
This is what I want to be able to do:
$association = Association::find(49);
$association->members->active()->count();
Now, I'm aware there's a difference between a Query and a Collection. But what I'm basically asking is if there's some kind of similar scope for collections. Of course, the optimal solution would be to not have to write TWO active methods, but use one for both purposes.
(question already answered in the comments, but might as well write a proper answer)
It is not possible to use a query scope in a Colletion, since query scope is a concept used in Eloquent to add constraints to a database query while Collections are just a collection of things (data, objects, etc).
In your case, what you need to do is to change this line:
$association->members->active()->count();
to:
$association->members()->active()->count();
This works because when we call members as a method, we are getting a QueryBuilder instance, and with that we can start chaining scopes to the query before calling the count method.
I have a pair of objects in laravel, pages and contents.
I have setup a relationship function, and include, which includes contents based on page_id.
I want to apply other conditions such as where deleted - 0, and where dates are within certain bounds, I know how to apply where conditions and set these field up.
What I can't fathom is how extra conditions can be applied as well as matching relationship fields.
Could anybody help me with this?
Defining the relationship in the model is all you need to do to the model itself. However you can add a static function to the model to get the data with the information you need.
Page model methods examples:
class Page extends Eloquent {
public function contents()
{
return $this->has_many('Content');
}
// Return all content that has not been marked as
// deleted in the database
public static function with_contents($id)
{
return Page::find($id)->contents()
->where_null('deleted')
->get();
}
}
This example assumes that the deleted field in the contents table is null unless it is deleted, in which case it will have any value.
To use you would simply use
$page = Page::with_contents('1');
You can create as many of these static helper methods as you like or add as many conditions to the one method as you like, then use your new static methods to retrieve your data.
I think this might be what you're looking for
http://doginthehat.com.au/2012/06/adding-conditions-to-relationships-in-laravel/
class User extends Eloquent {
public function meta()
{
return $this->has_many('Meta','target_id')
->where('target_type','=',$this->table());
}
}