There's the save and saveMany methods on the HasMany relation class, but where are the dissociate(Many)/detach(Many) methods? There's also no built-in way to get the inverse relationship method, so what's the best way to dissociate an array of id's/models from a HasMany relationship object.
Currently I'm using:
$hasMany = $parent->theRelationship(); // Get the relationship object.
$child = $hasMany->getRelated(); // Get an empty related model.
$key = $hasMany->getForeignKeyName(); // Get the name of the column on the child to set to NULL.
$child->findMany($IDs)->each(function($model) use ($key) {
$model->$key = NULL;
$model->save();
});
This could be alot shorter with something like:
$hasMany = $parent->theRelationship();
$hasMany->dissociate($IDs);
Bonus points if you have any official answers from Taylor as to why he hasn't implemented this, I've seen him close feature requests of this kind on GitHub.
I am not sure why there isn't a function, but to be more performant than your example, you could use the DB class like:
\DB::table('child_table')->where('parent_id', $parent->id)->update(['parent_id' => null]);
You could use detach like so;
$parent->theRelationship()->detach([1,2,3])
Where you pass an array of IDs.
From Laravel documentation:
"For convenience, attach and detach also accept arrays of IDs as input"
The performatic way (1 db update):
$partent->theRelationship()->update(['parent_id' => null]);
The readable way (multiple db updates):
$parent->theRelationship->each->parentRelationship()->dissociate();
So, in order to check the existence of a relationship on a model, we use the has function on the relationship like model1->has('relationship1').
While it is possible to supply the model1->with() function with an array of relations to eager load them all, both has and whereHas functions do not accept arrays as parameters. How to check for the existence of multiple relationships?
Right now, I am running multiple has functions on the same model (The relations are not nested):
model1->has('relationship1')
->has('relationship2')
->has('relationship3')
But that is tedious and error-prone. Solution anyone?
There unfortunately isn't a way to pass an array of relationships to has() or whereHas(), but you can use a QueryScope instead. On your Model, define the following:
public function scopeCheckRelationships($query){
return $query->has("relationship1")->has("relationship2")->has("relationship3");
}
Then, when querying your Model in a Controller, simply run:
$result = Model::checkRelationships()->get();
The function name to use a Scope is the name of the function, minus the word scope, so scopeCheckRelationships() is used as checkRelationships().
Also, it's actually possible to pass the relationships you want to query as a param:
public function scopeCheckRelationships($query, $relationships = []){
foreach($relationships AS $relationship){
$query->has($relationship);
// Might need to be `$query = $query->has(...);`, but I don't think so.
}
return $query;
}
...
$result = Model::checkRelationships(["relationship1", "relationship2", "relationship3"])->get();
In case you need this to be dynamic.
Here's the documentation for Query Scopes if you need more info: https://laravel.com/docs/5.8/eloquent#query-scopes
Using Laravel 5.3, I have a model with the following function
public function myData() {
return $this->hasMany(MyData::class);
}
and in my collection I have the following
$my_data = MyModel->myData()->get();
All good so far. If I return $my_data I get an eloquent collection with three items.
What I need now though is to create a duplicate of that collection but containing only three of the fields.
I have tried several different things, each of which return an error. The following is the closest I have got, but this returns an empty array - I assume because the fields are located one level deeper than the collection object.
$new_collection = $my_data->only(['field_1', 'field_2', 'field_3']);
What would be the correct way to create a new collection containing all three items, each with only the three selected fields?
Thanks for your help
You could use map:
$slimmed_down = $collection->map(function ($item, $key) {
return [
'field_1' => $item->field_1,
'field_2' => $item->field_2,
'field_3' => $item->field_3
];
});
This will return a new Collection with just the values you want. As far as I know there isn't any other method that does what you want, so iterating over every item and selecting the fields this way is one of the few solutions.
The advantage of using map instead of a standard foreach loop is that when you use map it returns a new instance of Collection.
Edit:
After some thoughts and research about this, the problem you'll have created is that the all the values in the Collection aren't instances of anything anymore. If you don't mind this effect, an even prettier and faster way would be to do this:
$slimmed_down = $collection->toArray()->only(['field_1', 'field_2', 'field_3']);
This basically has the same result.
Using Laravel 9, I just had the same issue :
$my_data->only(['field_1', 'field_2', 'field_3']);
returning an empty array.
I solved it with :
$my_data->map->only(['field_1', 'field_2', 'field_3']);
lets say I have 7 columns in table, and I want to select only two of them, something like this
SELECT `name`,`surname` FROM `table` WHERE `id` = '1';
In laravel eloquent model it may looks like this
Table::where('id', 1)->get();
but I guess this expression will select ALL columns where id equals 1, and I want only two columns(name, surname). how to select only two columns?
You can do it like this:
Table::select('name','surname')->where('id', 1)->get();
Table::where('id', 1)->get(['name','surname']);
You can also use find() like this:
ModelName::find($id, ['name', 'surname']);
The $id variable can be an array in case you need to retrieve multiple instances of the model.
By using all() method we can select particular columns from table like as shown below.
ModelName::all('column1', 'column2', 'column3');
Note: Laravel 5.4
You first need to create a Model, that represent that Table and then use the below Eloquent way to fetch the data of only 2 fields.
Model::where('id', 1)
->pluck('name', 'surname')
->all();
Also Model::all(['id'])->toArray() it will only fetch id as array.
Get value of one column:
Table_Name::find($id)->column_name;
you can use this method with where clause:
Table_Name::where('id',$id)->first()->column_name;
or use this method for bypass PhpStorm "Method where not found in App\Models":
Table_Name::query()->where('id','=',$id)->first()->column_name;
in query builder:
DB::table('table_names')->find($id)->column_name;
with where cluase:
DB::table('table_names')->where('id',$id)->first()->column_name;
or
DB::table('table_names')->where('id',$id)->first('column_name');
last method result is array
You can use get() as well as all()
ModelName::where('a', 1)->get(['column1','column2']);
From laravel 5.3 only using get() method you can get specific columns of your table:
YouModelName::get(['id', 'name']);
Or from laravel 5.4 you can also use all() method for getting the fields of your choice:
YourModelName::all('id', 'name');
with both of above method get() or all() you can also use where() but syntax is different for both:
Model::all()
YourModelName::all('id', 'name')->where('id',1);
Model::get()
YourModelName::where('id',1)->get(['id', 'name']);
To get the result of specific column from table,we have to specify the column name.
Use following code : -
$result = DB::Table('table_name')->select('column1','column2')->where('id',1)->get();
for example -
$result = DB::Table('Student')->select('subject','class')->where('id',1)->get();
use App\Table;
// ...
Table::where('id',1)->get('name','surname');
if no where
Table::all('name','surname');
If you want to get a single value from Database
Model::where('id', 1)->value('name');
Also you can use pluck.
Model::where('id',1)->pluck('column1', 'column2');
You can use Table::select ('name', 'surname')->where ('id', 1)->get ().
Keep in mind that when selecting for only certain fields, you will have to make another query if you end up accessing those other fields later in the request (that may be obvious, just wanted to include that caveat). Including the id field is usually a good idea so laravel knows how to write back any updates you do to the model instance.
You can get it like
`PostModel::where('post_status', 'publish')->get(['title', 'content', 'slug', 'image_url']`)
link
you can also used findOrFail() method here it's good to used
if the exception is not caught, a 404 HTTP response is automatically sent back to the user. It is not necessary to write explicit checks to return 404 responses when using these method not give a 500 error..
ModelName::findOrFail($id, ['firstName', 'lastName']);
While most common approach is to use Model::select,
it can cause rendering out all attributes defined with accessor methods within model classes. So if you define attribute in your model:
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class User extends Model
{
/**
* Get the user's first name.
*
* #param string $value
* #return string
*/
public function getFirstNameAttribute($value)
{
return ucfirst($value);
}
}
And then use:
TableName::select('username')->where('id', 1)->get();
It will output collection with both first_name and username, rather than only username.
Better use pluck(), solo or optionally in combination with select - if you want specific columns.
TableName::select('username')->where('id', 1)->pluck('username');
or
TableName::where('id', 1)->pluck('username'); //that would return collection consisting of only username values
Also, optionally, use ->toArray() to convert collection object into array.
If you want to get single row and from the that row single column, one line code to get the value of the specific column is to use find() method alongside specifying of the column that you want to retrieve it.
Here is sample code:
ModelName::find($id_of_the_record, ['column_name'])->toArray()['column_name'];
If you need to get one column calling pluck directly on a model is the most performant way to retrieve a single column from all models in Laravel.
Calling get or all before pluck will read all models into memory before plucking the value.
Users::pluck('email');
->get() much like ->all() (and ->first() etc..) can take the fields you want to bring back as parameters;
->get/all(['column1','column2'])
Would bring back the collection but only with column1 and column2
You can use the below query:
Table('table')->select('name','surname')->where('id',1)->get();
If you wanted to get the value of a single column like 'name', you could also use the following:
Table::where('id', 1)->first(['name'])->name;
For getting multiple columns (returns collection) :
Model::select('name','surname')->where('id', 1)->get();
If you want to get columns as array use the below code:
Model::select('name','surname')->where('id', 1)->get()->toArray();
If you want to get a single column try this:
Model::where('id', 1)->first(['column_name'])->column_name;
In Laravel 4.2 I have a model called Product with many-to-many relationshis to other models like Country or Category. I want to filter out products that are "incomplete", which means they have no connected countries or no connected categories. I can use whereDoesntHave() method to filter out one relation. When I use it two times in one query it creates AND condition, but I need OR. I can't find orWhereDoesntHave() method in API documentation. I can't pass multiple relations as arguments because it expects first argument to be a string.
I need something like this:
$products = Product::whereDoesntHave('categories')->orWhereDoesntHave('countries')->get();
Is there any way to achive whereDoesntHave() with multiple OR conditions?
You can use doesntHave and specify the boolean operator:
$products = Product::doesntHave('categories')->doesntHave('countries', 'or')->get();
Actually you only need whereDoesntHave if you want to pass in a closure to filter the related models before checking if any of them exist. In case you want to do that you can pass the closure as third argument:
$products = Product::doesntHave('categories', 'or', function($q){
$q->where('active', false);
})->doesntHave('countries', 'or')->get();
Since Laravel 5.5 there is an orWhereDoesntHave function.
You may use it like this
Product::whereDoesntHave('categories', function($q){ //... })
->orWhereDoesntHave('countries', function($q){//...})
->get();
From you example it seems that you are not using a where clause, so you may just use
Product::doesntHave('categories')
->orDoesntHave('countries')
->get();
Use
Product::whereDoesntHave('categories')->doesntHave('countries', 'or')->get();
Laravel Source Code:
whereDoesntHave https://github.com/illuminate/database/blob/master/Eloquent/Builder.php#L654
calls
https://github.com/illuminate/database/blob/master/Eloquent/Builder.php#L628
internally.
Let’s say we have Authors and Books, with 1-n relationship – one Author can have one or many Books. Here’s how it looks in app\Author.php:
public function books()
{
return $this->hasMany(\App\Book::class, 'author_id');
}
Now, what if we want to show only those Authors that have at least one book? Simple, there’s method has():
$authors = Author::has('books')->get();
Similarly, there’s an opposite method – what if we want to query only the authors without any books? Use doesnthave():
$authors = Author::doesnthave('books')->get();
It’s not only convenient, but also super-easy to read and understand, even if you’re not a Laravel developer, right?