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Property [title] does not exist on this collection instance
(8 answers)
Closed 5 years ago.
I'm using Laravel 5.5.
I'm trying to get an object instance with the Query Builder of Laravel.
public function functionName(Request $request) {
$seance = Seance::where('id_seance', '=', $request->idSeance)->get();
return $seance->type_seance;
}
My model : Seance(id_seance, type_seance, capacite_seance, niveau_seance, avec_coach, date_seance, heure_seance).
However I get this error :
Exception: Property [type_seance] does not exist on this collection
instance
Thank's for help!
Get() method return a collection object it's like an array, you need to use first method to get the first object:
public function functionName(Request $request) {
$seance = Seance::where('id_seance', '=', $request->idSeance)->first();
return $seance->type_seance;
}
You can use find() method too but id_seance should be the primary key of your table:
$seance = Seance::find($request->idSeance);
return $seance->type_seance;
Use first() instead of get() to get an object instead of collection of objects:
$seance = Seance::where('id_seance', $request->idSeance)->first();
The difference between these methods is explained here.
When using the get() method, it will return a collection rather than an instance of the model. I suggest using thefirst() method instead.
Better yet, useSeance::find($request->idSeance) or Seance::findOrFail($request->idSeance). This assumes that you've defined your primary key on your model correctly.
Related
There is some basic understanding/theory here that I am missing.I don't understand the difference between these function calls:
$distributors = $store->distributors();
$distributors = $store->distributors;
$distributors = $store->distributors()->get();
$distributors = $store->distributors->get();
What I am trying to accomplis here is to get a list of the distributors for a store (a many to many relationship), and they get each distributors list of beers into one giant list.
foreach ($distributors as $distributor)
{
$available_beers = array_merge($distributor->beers(), $available_beers);
}
I don't know if that is the best way to do this and I can't get it to work. Similar to the first list of methods, I don't know if I need ->$beers or ->$beers()
Update
Thanks to everyone who answered! This will be a good reference for me going forward. My biggest lesson was the difference between getting a collection back, vs getting the query builder/relationship object back. For future reference to those who find this question, here is what I set up in my controller:
$store = $this->store->find($id)->first();
$distributors = $store->distributors;
$beers = [];
foreach ($distributors as $distributor){
$beers = array_merge($distributor->beers->lists('name', 'id'), $beers);
}
Short answer
$model->relation() returns the relationship object
$model->relation returns the result of the relationship
Long answer
$model->relation() can be explained pretty simple. You're calling the actual function you defined your relation with. Yours for distributor probably looks somewhat like this:
public function distributors(){
return $this->hasMany('Distributor');
}
So when calling $store->distributors() you just get the return value of $this->hasMany('Distributor') which is an instance of Illuminate\Database\Eloquent\Relations\HasMany
When do you use it?
You usually would call the relationship function if you want to further specify the query before you run it. For example add a where statement:
$distributors = $store->distributors()->where('priority', '>', 4)->get();
Of course you can also just do this: $store->distributors()->get() but that has the same result as $store->distributors.
Which brings me to the explanation of the dynamic relationship property.
Laravel does some things under the hood to allow you to directly access the results of a relationship as property. Like: $model->relation.
Here's what happens in Illuminate\Database\Eloquent\Model
1) The properties don't actually exist. So if you access $store->distributors the call will be proxied to __get()
2) This method then calls getAttribute with the property name getAttribute('distributors')
public function __get($key)
{
return $this->getAttribute($key);
}
3) In getAttribute it checks if the relationship is already loaded (exists in relations). If not and if a relationship method exists it will load the relation (getRelationshipFromMethod)
public function getAttribute($key)
{
// code omitted for brevity
if (array_key_exists($key, $this->relations))
{
return $this->relations[$key];
}
$camelKey = camel_case($key);
if (method_exists($this, $camelKey))
{
return $this->getRelationshipFromMethod($key, $camelKey);
}
}
4) In the end Laravel calls getResults() on the relation which then results in a get() on the query builder instance. (And that gives the same result as $model->relation()->get().
The direct answer to your question:
$store->distributors() will return the actual relationship object (\Illuminate\Database\Eloquent\Relations\BelongsToMany).
$store->distributors will be a collection containing the results of the relationship query (\Illuminate\Database\Eloquent\Collection).
$store->distributors()->get() will be a collection containing the results of the relationship query (\Illuminate\Database\Eloquent\Collection).
$store->distributors->get() should return an error since you're calling get() on a Collection object and the first parameter is not optional. If not an error, it should at least return null.
More information:
Given the following model:
class Store extends Eloquent {
public function distributors() {
return $this->belongsToMany('Distributor');
}
}
Calling the relationship method ($store->distributors()) will return to you the relationship (\Illuminate\Database\Eloquent\Relations\BelongsToMany) object. This is basically a query object which you can continue to modify, but you still need to call some type of method to get the results (e.g. get(), first(), etc).
However, accessing the relationship attribute ($store->distributors) will return to you a collection (\Illuminate\Database\Eloquent\Collection) object containing the results from executing the relationship query.
By default, the relationship attribute is created and assigned a value the first time it is accessed (known as "lazy loading"). So, the first time you access $store->distributors, behind the scenes it is executing the relationship query, storing the results in the $store->distributors attribute, and then returning those results. However, it only does this once. The next time you access $store->distributors, the attribute already contains the data, so that is what you are accessing.
To illustrate this:
// the following two statements will run the query twice
$r1 = $store->distributors()->get();
$r2 = $store->distributors()->get();
// the following two statements will run the query once.
// the first statement runs the query, populates $store->distributors, and assigns the variable
// the second statement just accesses the data now stored in $store->distributors
$r3 = $store->distributors;
$r4 = $store->distributors;
// at the end, $r1 == $r2 == $r3 == $r4
Relationships can also be "eager" loaded, using the with() method on the query. This is done to alleviate all of the extra queries that may be needed for lazy loading (known as the n+1 problem). You can read more about that here.
When you work with relationships with Eloquent the property is a collection (Illuminate\Database\Eloquent\Collection) of your relation white the method is a start of a new query.
Say your model looks like this:
class User extends Eloquent {
public function roles()
{
return $this->belongsToMany('Role');
}
}
If you try to access $user->roles, Eloquent will run the query and fetch all roles related to that user thanks to magic methods and returns an instance of Illuminate\Database\Eloquent\Collection. That class has a method called get, that's why $user->roles->get() works for you.
If you try to access the method, $user->roles(), you will instead get a query builder object so you can fine tune your query.
$user->roles()->whereIn('role_id', [1, 3, 4])->get();
That would only return roles where role_id is 1, 3 or 4.
So, the property returns a complete query and it results (Illuminate\Database\Eloquent\Collection) while the method lets you customize your query.
$distributors = $store->distributors();
Result of a method (function)
$distributors = $store->distributors;
Value of property (variable)
$distributors = $store->distributors()->get();
Take the first one, where it's the result of a method, if the method returns an object, this is a method in that object that was returned.
$distributors = $store->distributors->get();
If the property is an object, then it's calling a method in that property that's an object.
Re ->$beers vs ->$beers() that's a dynamic name of a property/method depending on what you're for. Just make a really rough guess at what you're doing, in your class you're going to have
$this->beers = array('bud','miller','sam');
and in your code using the $store object, you're actually going to go something like
$drink_type = 'beers';
$drink_list = $store->$drink_type;
And that will return $this->beers from $store, the same as writing $store->beers;
Imagine that the store class looks like this:
<?php
class Store {
public $distributors;
function __construct($distributors = array()) {
$this->distributors = $distributors;
}
public function distributors() {
return $this->distributors;
}
}
So the difference is:
$store = new Store(array('some guy', 'some other guy'));
$guys = $store->distributors; # accesing the $distributors property
$more = $store->distributors(); # calling the distributors() method.
The main difference is:
$distributors = $store->distributors() return instance of the relationship object like Illuminate\Database\Eloquent\Relations\BelongsToMany. You can use other conditions such as where after call this.
$store->distributors return instance of the collection Illuminate/Database/Eloquent/Collection. Laravel call the magic method __get under the hood. It will return a result of query relationship.
Maybe this will be usefull.
Access to method:
$object->method();
Access to property:
$object->property;
I'm working fixing a project and I made a scope in a model to query a relationship which also executes a closure:
This is the scope, it's a hotel:
public function scopeIsHotelAvailable($query, $start_date, $end_date){
return $query->whereHas('isAvailableInRanges', function($q) use ($start_date, $end_date) {
$q->isAvailableInRanges($start_date, $end_date);
});
}
When I even attempt at running this I get the following error:
$hotel->ishotelavailable($start, $end);
TypeError: Too few arguments to function Modules/Hotel/Models/Hotel::isAvailableInRanges(), 0 passed in /home/ffuentes/pk2/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Concerns/QueriesRelationships.php on line 475 and exactly 2 expected
I've seen this before but I don't know how to make Eloquent recognize the arguments.
EDIT:
This is the method being called from the closure which is part of the model Hotel.
public function isAvailableInRanges($start_date,$end_date){
$days = max(1,floor((strtotime($end_date) - strtotime($start_date)) / DAY_IN_SECONDS));
if($this->default_state)
{
$notAvailableDates = $this->hotelDateClass::query()->where([
['start_date','>=',$start_date],
['end_date','<=',$end_date],
['active','0']
])->count('id');
if($notAvailableDates) return false;
}else{
$availableDates = $this->hotelDateClass::query()->where([
['start_date','>=',$start_date],
['end_date','<=',$end_date],
['active','=',1]
])->count('id');
if($availableDates <= $days) return false;
}
// Check Order
$bookingInRanges = $this->bookingClass::getAcceptedBookingQuery($this->id,$this->type)->where([
['end_date','>=',$start_date],
['start_date','<=',$end_date],
])->count('id');
if($bookingInRanges){
return false;
}
return true;
}
The point of all this is to test the query results against these results and filter them. Back then when I begun trying it I just filtered the collection but it didn't work because the collection returned didn't include pagination and the eloquent elements it usually carries within itself.
Problems 1:
You're using a scope method instead of relationship, try to use relationship method in whereHas, like:
->whereHas('yourRelationshipMethod', function($q) {...});
Problem 2:
The isAvailableInRanges is in Hotel model, so you can call it by Hotel, not relationship model.
Problem 3:
But the isAvailableInRanges is a instance method, so you cannot just call it by Eloquent builder, you need to get the instance and call this method:
Hotel::first()->isAvailableInRanges($start_date,$end_date);
I am trying to fetch the the id and the name of the categories which is related to my services. A service has many categories and a categories belongs to a services. However when I try to get the id and the name as an array to return it gives me this error.
array_key_exists(): The first argument should be either a string or an
integer.
Here is my method or function.
public function getCategories($idService)
{
$service = Service::findOrFail($idService);
return $service->categories->get(['id','name']);;
}
and here is the defined route.
Route::get('service/{service}/categories', 'ServiceController#getCategories');
I tried to look and browse for it but can't find any solution at all.
Use pluck() method instead
return $service->categories->pluck('id','name');
The name of the parameter has to be equal to the wildcard and you need to use pluck() as mentioned in another comment, in your case:
public function getCategories($service)
{
$service = Service::findOrFail($service);
return $service->categories->pluck(['id','name']);
}
If service is a model you can also use eloquent:
public function getCategories(Service $service)
{
return $service->categories->pluck(['id','name']);
}
i guess it related to with eager loading..need to use eager loading to fetch the relationship.. then use laravel collection if you want to filter more
public function getCategories($idService)
{
return Service::with(['categories' => function ($query) {
$query->select('id', 'name');
}])->findOrFail($idService);
}
There is some basic understanding/theory here that I am missing.I don't understand the difference between these function calls:
$distributors = $store->distributors();
$distributors = $store->distributors;
$distributors = $store->distributors()->get();
$distributors = $store->distributors->get();
What I am trying to accomplis here is to get a list of the distributors for a store (a many to many relationship), and they get each distributors list of beers into one giant list.
foreach ($distributors as $distributor)
{
$available_beers = array_merge($distributor->beers(), $available_beers);
}
I don't know if that is the best way to do this and I can't get it to work. Similar to the first list of methods, I don't know if I need ->$beers or ->$beers()
Update
Thanks to everyone who answered! This will be a good reference for me going forward. My biggest lesson was the difference between getting a collection back, vs getting the query builder/relationship object back. For future reference to those who find this question, here is what I set up in my controller:
$store = $this->store->find($id)->first();
$distributors = $store->distributors;
$beers = [];
foreach ($distributors as $distributor){
$beers = array_merge($distributor->beers->lists('name', 'id'), $beers);
}
Short answer
$model->relation() returns the relationship object
$model->relation returns the result of the relationship
Long answer
$model->relation() can be explained pretty simple. You're calling the actual function you defined your relation with. Yours for distributor probably looks somewhat like this:
public function distributors(){
return $this->hasMany('Distributor');
}
So when calling $store->distributors() you just get the return value of $this->hasMany('Distributor') which is an instance of Illuminate\Database\Eloquent\Relations\HasMany
When do you use it?
You usually would call the relationship function if you want to further specify the query before you run it. For example add a where statement:
$distributors = $store->distributors()->where('priority', '>', 4)->get();
Of course you can also just do this: $store->distributors()->get() but that has the same result as $store->distributors.
Which brings me to the explanation of the dynamic relationship property.
Laravel does some things under the hood to allow you to directly access the results of a relationship as property. Like: $model->relation.
Here's what happens in Illuminate\Database\Eloquent\Model
1) The properties don't actually exist. So if you access $store->distributors the call will be proxied to __get()
2) This method then calls getAttribute with the property name getAttribute('distributors')
public function __get($key)
{
return $this->getAttribute($key);
}
3) In getAttribute it checks if the relationship is already loaded (exists in relations). If not and if a relationship method exists it will load the relation (getRelationshipFromMethod)
public function getAttribute($key)
{
// code omitted for brevity
if (array_key_exists($key, $this->relations))
{
return $this->relations[$key];
}
$camelKey = camel_case($key);
if (method_exists($this, $camelKey))
{
return $this->getRelationshipFromMethod($key, $camelKey);
}
}
4) In the end Laravel calls getResults() on the relation which then results in a get() on the query builder instance. (And that gives the same result as $model->relation()->get().
The direct answer to your question:
$store->distributors() will return the actual relationship object (\Illuminate\Database\Eloquent\Relations\BelongsToMany).
$store->distributors will be a collection containing the results of the relationship query (\Illuminate\Database\Eloquent\Collection).
$store->distributors()->get() will be a collection containing the results of the relationship query (\Illuminate\Database\Eloquent\Collection).
$store->distributors->get() should return an error since you're calling get() on a Collection object and the first parameter is not optional. If not an error, it should at least return null.
More information:
Given the following model:
class Store extends Eloquent {
public function distributors() {
return $this->belongsToMany('Distributor');
}
}
Calling the relationship method ($store->distributors()) will return to you the relationship (\Illuminate\Database\Eloquent\Relations\BelongsToMany) object. This is basically a query object which you can continue to modify, but you still need to call some type of method to get the results (e.g. get(), first(), etc).
However, accessing the relationship attribute ($store->distributors) will return to you a collection (\Illuminate\Database\Eloquent\Collection) object containing the results from executing the relationship query.
By default, the relationship attribute is created and assigned a value the first time it is accessed (known as "lazy loading"). So, the first time you access $store->distributors, behind the scenes it is executing the relationship query, storing the results in the $store->distributors attribute, and then returning those results. However, it only does this once. The next time you access $store->distributors, the attribute already contains the data, so that is what you are accessing.
To illustrate this:
// the following two statements will run the query twice
$r1 = $store->distributors()->get();
$r2 = $store->distributors()->get();
// the following two statements will run the query once.
// the first statement runs the query, populates $store->distributors, and assigns the variable
// the second statement just accesses the data now stored in $store->distributors
$r3 = $store->distributors;
$r4 = $store->distributors;
// at the end, $r1 == $r2 == $r3 == $r4
Relationships can also be "eager" loaded, using the with() method on the query. This is done to alleviate all of the extra queries that may be needed for lazy loading (known as the n+1 problem). You can read more about that here.
When you work with relationships with Eloquent the property is a collection (Illuminate\Database\Eloquent\Collection) of your relation white the method is a start of a new query.
Say your model looks like this:
class User extends Eloquent {
public function roles()
{
return $this->belongsToMany('Role');
}
}
If you try to access $user->roles, Eloquent will run the query and fetch all roles related to that user thanks to magic methods and returns an instance of Illuminate\Database\Eloquent\Collection. That class has a method called get, that's why $user->roles->get() works for you.
If you try to access the method, $user->roles(), you will instead get a query builder object so you can fine tune your query.
$user->roles()->whereIn('role_id', [1, 3, 4])->get();
That would only return roles where role_id is 1, 3 or 4.
So, the property returns a complete query and it results (Illuminate\Database\Eloquent\Collection) while the method lets you customize your query.
$distributors = $store->distributors();
Result of a method (function)
$distributors = $store->distributors;
Value of property (variable)
$distributors = $store->distributors()->get();
Take the first one, where it's the result of a method, if the method returns an object, this is a method in that object that was returned.
$distributors = $store->distributors->get();
If the property is an object, then it's calling a method in that property that's an object.
Re ->$beers vs ->$beers() that's a dynamic name of a property/method depending on what you're for. Just make a really rough guess at what you're doing, in your class you're going to have
$this->beers = array('bud','miller','sam');
and in your code using the $store object, you're actually going to go something like
$drink_type = 'beers';
$drink_list = $store->$drink_type;
And that will return $this->beers from $store, the same as writing $store->beers;
Imagine that the store class looks like this:
<?php
class Store {
public $distributors;
function __construct($distributors = array()) {
$this->distributors = $distributors;
}
public function distributors() {
return $this->distributors;
}
}
So the difference is:
$store = new Store(array('some guy', 'some other guy'));
$guys = $store->distributors; # accesing the $distributors property
$more = $store->distributors(); # calling the distributors() method.
The main difference is:
$distributors = $store->distributors() return instance of the relationship object like Illuminate\Database\Eloquent\Relations\BelongsToMany. You can use other conditions such as where after call this.
$store->distributors return instance of the collection Illuminate/Database/Eloquent/Collection. Laravel call the magic method __get under the hood. It will return a result of query relationship.
Maybe this will be usefull.
Access to method:
$object->method();
Access to property:
$object->property;
I have a collection and I am calling first() method on it with a closure expecting a parameter say $model.
Upon execution, if I try to access a property of $model; it says:
Accessing property of non-object
I tried dumping $model and found that it has a integer 1 instead of Object.
$Collection->first( function($model) {
if(!$model) return false;
return $model->type == 'Test';
});
I just got it working. The first() method's argument closure is provided with 2 variables. First one is the key and second one is the model. So, you will call first() method like below and if it satisfies the criteria you defined, just return true.
$result = $collection->first( function($i, $model) {
// define criteria and return true if it satisfies. The model will now be returned in resulting Collection.
});