I have a table that has a one-to-many relationship with another table.
Call them tables parent and child
child has a field called field1
I am trying to get an array of all field1 values.
In the parent Model, I have this function that gets me all children of parent
public function children()
{
return $this->hasMany(Child::class);
}
Now, in the parent model, I also want to get all field1 values.
I can get all the children like so:
$children = $this->children->all();
But I just can't figure out how to then index into this to get all the field1 values.
Maybe it is better to just use $this->children in which case it is a Collection and then use some sort of Collection method to extract field1?
I tried
$this->children->only(['field1'])
but that returned nothing, even though field1 certain exists.
Ideas?
Thanks!
You can use pluck method of collecion to get an array of field1 values:
$parent->child->pluck('field1');
Or better, you can use pluck method of query builder (see section Retrieving A List Of Column Values), being even more efficient, with same result:
$parent->child()->pluck('field1');
map() is the function you are looking.
$children = $this->children->all()->map(function($children) {
return $children->field1;
});
A shorter version using Higher Order Message.
$children = $this->children->all()->map->field1;
Related
I have a table with types, and second table "cleanings" with a related type_id column.
I get a collection of all cleanings:
$cleanings= Cleaning::with(['propierty'])->get();
And now, I need to split this collection in many collections(or arrays), one for every type_id.
Is there any trick to do it? I can't find any method in collections page for that.
$array = [];
foreach($cleanings as $cleaning) {
$array[$cleaning->type_id][] = $cleaning;
}
This'll give you an array of arrays, keyed by type_id.
I have a challenge that if I want to sort the records when getting using Laravel's ORM based on a list of IDs, how should I do it?!!!!!!!
I mean :
Suppose we have a table called users, which contains 100 records and each record has a unique ID.
We also have an array of IDs.
$ids = [4,1,2,3]
Now I want to get the list of users, but only the users who are first in the ids array and secondly according to the same order as they are listed in this array.
User::whereIn('id' , $Ids)->sortBy('id',$ids)->get();
Can you think of a solution to do this?
User::whereIn('id' , $Ids)->sortBy('id',$ids)->get();
The collections sortBy() function can take a custom call back this way:
$users = User::whereIn('id', $Ids)->get()
->sortBy(function($user, $key) use($ids) {
return array_search($user->id, $ids);
});
This will sort your collection according to the given array.
You can also reference the docs for more information.
Note that the sortBy() function must act upon a collection, which means that the get() function must come before it.
I have used some accessors for Model attributes.
And as my knowledge about Accessor in Laravel, it can use to create a virtual attribute based on another attribute value or modify the return value of the existing attribute.
So I create an Accessor with the public method getStatusAttribute to convert the status from integer to string value. For example, my Model has an attribute named is 'status'. In DB, this column is stored with integers like 0,1,2,...
In this method, the return value is a string based on the current status attribute value.
public function getStatusAttribute(int $value): string
{
$statuses = [
1 => 'New',
2 => 'Pending',
3 => 'Canceled'
];
return $statuses[$value];
}
Everything work fined when I retrieve attribute value from the model object entity.
But when I want to retrieve an Eloquent Collection with a specific 'status' attribute value, the $value parameter in the 'where' method expects a string value that is returned from the accessor method, not is an integer value which stored in a database. So the $value parameter would be 'New' or 'Pending' or 'Canceled' instead of 1,2,3.
I want to retrieve a collection that contains an Eloquent Model Object so that I won't use an Illuminate\Support\Facades\DB.
I know I still can retrieve the exact collection with the $value parameter as a string, but I was just wondering if we have another way to skip the accessor in the query of Eloquent Collection?
Please see an example below for more detail about what I expect.
For example, some records in the database look like the below, and the model was named 'DemoModel' :
id
status
1
1
2
3
3
1
4
3
5
2
public function getCanceledEntities($entityId)
{
$canceledEntities = DemoModel::all()->where('status', '=', 3);
if($canceledEntities->isNotEmpty()) {
return $canceledEntities;
}
}
Without an accessor, this query will return a collection containing two entities with id [ 2, 4 ].
But with an accessor (as defined in the model), it can't find a matched entity because the WHERE clause expects that the 3rd parameter is 'Canceled' instead of 3.
My alternative method is to use a string 'Canceled' in the 'where' clause. However, I still want to use the value stored in a database for the query, and I think maybe the framework has another way to write an Eloquent Collection query without invoking an accessor.
Any suggestions are always welcome.
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 :
$my_data->map->only(['field_1', 'field_2', 'field_3']);
I am new to laravel and confused about some query methods.
find($id) is useful and returns a nice array, but sometimes I need to select by other fields rather than id.
The Laravel document said I could use where('field', '=', 'value') and return a bunch of data, which is fine.
What I can't understand is why I need to add ->first() every time, even if I am pretty sure there is only one single row matches the query.
It goes like this:
$query->where(..)->orderBy(..)->limit(..) etc.
// you can chain the methods as you like, and finally you need one of:
->get($columns); // returns Eloquent Collection of Models or array of stdObjects
->first($columns); // returns single row (Eloquent Model or stdClass)
->find($id); // returns single row (Eloquent Model or stdClass)
->find($ids); // returns Eloquent Collection
// those are examples, there are many more like firstOrFail, findMany etc, check the api
$columns is an array of fields to retrieve, default array('*')
$id is a single primary key value
$ids is an array of PKs, this works in find method only for Eloquent Builder
// or aggregate functions:
->count()
->avg()
->aggregate()
// just examples here too
So the method depends on what you want to retrieve (array/collection or single object)
Also the return objects depend on the builder you are using (Eloquent Builder or Query Builder):
User::get(); // Eloquent Colleciton
DB::table('users')->get(); // array of stdObjects
even if I am pretty sure there is only one single row matches the query.
Well Laravel cant read your mind - so you need to tell it what you want to do.
You can do either
User::where('field', '=', 'value')->get()
Which will return all objects that match that search. Sometimes it might be one, but sometimes it might be 2 or 3...
If you are sure there is only one (or you only want the first) you can do
User::where('field', '=', 'value')->first()
get() returns an array of objects (multiple rows)
while
first() returns a single object (a row)
You can of course use get() when you know it will return only one row, but you need to keep that in mind when addressing the result:
using get()
$rez = \DB::table('table')->where('sec_id','=','5')->get();
//will return one row in an array with one item, but will be addressed as:
$myfieldvalue = $rez[0]->fieldname;
using first()
$rez = \DB::table('table')->where('sec_id','=','5')->first();
// will also return one row but without the array, so
$myfieldvalue = $rez->fieldname;
So it depends on how you want to access the result of the query: as an object or as an array, and also depends on what "you know" the query will return.
first() is the equivalent of LIMIT 1 at the end of your SELECT statement. Even if your query would return multiple rows, if you use first() it will only return the first row