I'm new to Laravel,
let me straight forward to the question.
Suppose I have 'Posts' table and 'Comments' table
And the first 'Post' has 3 comments,
What is the best query method to achieve this kind of result
Post => (
[0]=> array (
[id]=>1
[content]=> This is my first Post!
[comments]=> array(
[0]=>array(
[id]=>1
[post_id]=>1
[content]=> First comment!
)
[1]=>array(
[id]=>2
[post_id]=>1
[content]=> Second comment!
)
[2]=>array(
[id]=>3
[post_id]=>1
[content]=> Third comment!
)
)
)
)
Eager load the relationship:
$posts = Post::with('comments')->get()->toArray();
You can use Eloquent relationships. https://laravel.com/docs/5.4/eloquent-relationships#one-to-many.
The example is exactly what you're looking for! (:
Related
Looking some examples ( https://www.elutarkus.ee/tarkus/xO9eqyqewr6 ) how savemany works with many to many relations,
I did not find can I with similar code to fill additive fields in pivot table , like :
$post->comments()->saveMany([
new App\Comment(['message' => 'A new comment.'], $arratOfPivotTables),
new App\Comment(['message' => 'Another comment.'], $arratOfPivotTables),
]);
I tried and failed, no additive fields in pivot table were filled...
"laravel/framework": "^9.48.0",
Thanks in advance!
in sql query this commando do exactly i wanted:
SELECT
v.id,
(
SELECT sv.status_id
FROM status_viagem sv
WHERE sv.viagem_id = v.id
ORDER BY sv.created_at DESC LIMIT 1 ) AS status_id
FROM viagens v
Here is the sql results:
But i have no idea how can i do this using Laravel eloquent
Basically, a viagem entry can has a lot of status, but i need to get each viagem and their last status entry from status_viagem table (the pivot table)
by the way viagem/viagens means travel.
My class mapping:
class Viagem extends Model
{
...
public function status()
{
return $this->belongsToMany('App\Status')->withTimestamps();
}
...
}
class Status extends Model
{
public function viagens()
{
return $this->belongsToMany('App\Viagem')->withTimestamps();
}
}
The belongsToMany at both classes gets me a many-to-many:
can someone help me? thanks
---------- Temporary Solution -------
Thanks for all help guys. In fact i can't find a nice solution using only eloquent.
Step 1/3 - To bypass this situation i first execute the above sql to grab only the viagens under the desired status_id (last status_viagem entry):
$viagens_ids = DB::select(
"SELECT viagem_id FROM (
SELECT
v.id AS viagem_id,
(
SELECT sv.status_id
FROM status_viagem sv
WHERE sv.viagem_id = v.id
ORDER BY sv.id DESC LIMIT 1 ) AS status_id
FROM viagens v
) AS tt
WHERE tt.status_id = {$status->id}"
);
Step 2/3 - then i used the array_map to organize my viagens ids
$a = array_map(
function($obj) { return $obj->viagem_id; },
$viagens_ids
);
Step 3/3 - And at last i used elequent whereIn to fetch my viagens:
Viagem::with( 'status')->whereIn('id', $a)->get();
In fact i have solved the problem by a-old-sashion-way but i not happy with it because i wish i learn how to do it using eloquent. what bad to me.
There are many ways to query in laravel. I have created a test project for you to try. The gist are:
1. Eloquent ORM
Eloquent ORM is Laravel's magic which have some limitations in eager loading - which i just come across while contemplating your question for hours. It wont play nicely with first(), last(), and some more functions in the constrained eager loading closure.
In your case, our almost there can be fixed:
App\Models\Viagem::with(['status' => function($query){
return $query->orderBy('pivot_created_at', 'desc');
}])
->get()
It will return entire field for Viagem and Status including its pivot table (the status_viagem).
However, if you wanted to retrieve only viagem.id and status_viagem.status_id, you can map() it as such:
App\Models\Viagem::with(['status' => function($query){
return $query->orderBy('pivot_created_at', 'desc');
}])
->get()
->map(function($data){
$o = new stdClass();
$o->id = $data->id;
$o->status_id = $data->status->first()->id;
return $o;
});
Please take note that the statement above require sql query to be ran twice. Eager loading basically works by querying all the Viagem first then queries the Status and map them in memory based on the foreign keys. You can observe that replacing get with toSql will only give you the first query. Please enable Query Logging to see the second query.
2. Query Builder
Embarking from Ryan Adhitama Putra answer, you could do something like:
App\Models\Viagem::join('status_viagem', 'viagens.id', '=', 'status_viagem.viagem_id')
->orderBy('status_viagem.created_at', 'desc')
->groupBy(['status_viagem.status_id', 'viagens.id'])
->select(['viagens.id', 'status_viagem.status_id'])
->get();
This query builder approach guaranteed to be ran only once, you can replace the get() with toSql() to see the resulting query.
3. Raw Queries
Throwing DB::raw() can help sometime, but i really did not want to mention it.
I am not sure what viagens and viagem represent, but I think one of the relationships has to be belongsToMany() and the other hasMany().
then after you set relationships correctly, you can use Eloquent like this :
$status_id = Viagem::with('status')->orderBy('created_at', 'desc')->first()->pluck('status_id');
Try this.
$status_id = Viagem::join('status','viagem.id','status_viagem.viagem_id')
->select('viagem.id','status_viagem.status_id')
->get();
So I'm trying to get the number of distinct pids on a query, but the returned value is wrong.
This is what I try to do:
$ad->getcodes()->groupby('pid')->distinct()->count()
what returns the value "2", while the value it should return, should be "1".
As a workaround, I'm doing this:
count($ad->getcodes()->groupby('pid')->distinct()->get())
what works fine and returns "1"
Is there any rule where count and distinct cannot be on the same query? I find the workaround kind of "heavy", I would like to make the original query work :(
The following should work
$ad->getcodes()->distinct()->count('pid');
A more generic answer that would have saved me time, and hopefully others:
Does not work (returns count of all rows):
DB::table('users')
->select('first_name')
->distinct()
->count();
The fix:
DB::table('users')
->distinct()
->count('first_name');
Anyone else come across this post, and not finding the other suggestions to work?
Depending on the specific query, a different approach may be needed. In my case, I needed either count the results of a GROUP BY, e.g.
SELECT COUNT(*) FROM (SELECT * FROM a GROUP BY b)
or use COUNT(DISTINCT b):
SELECT COUNT(DISTINCT b) FROM a
After some puzzling around, I realised there was no built-in Laravel function for either of these. So the simplest solution was to use use DB::raw with the count method.
$count = $builder->count(DB::raw('DISTINCT b'));
Remember, don't use groupBy before calling count. You can apply groupBy later, if you need it for getting rows.
You can use the following way to get the unique data as per your need as follows,
$data = $ad->getcodes()->get()->unique('email');
$count = $data->count();
Hope this will work.
I had a similar problem, and found a way to work around it.
The problem is the way Laravel's query builder handles aggregates. It takes the first result returned and then returns the 'aggregate' value. This is usually fine, but when you combine count with groupBy you're returning a count per grouped item. So the first row's aggregate is just a count of the first group (so something low like 1 or 2 is likely).
So Laravel's count is out, but I combined the Laravel query builder with some raw SQL to get an accurate count of my grouped results.
For your example, I expect the following should work (and let you avoid the get):
$query = $ad->getcodes()->groupby('pid')->distinct();
$count = count(\DB::select($query->toSql(), $query->getBindings()));
If you want to make sure you're not wasting time selecting all the columns, you can avoid that when building your query:
$query = $ad->select(DB::raw(1))->getcodes()->groupby('pid')->distinct();
I came across the same problem.
If you install laravel debug bar you can see the queries and often see the problem
$ad->getcodes()->groupby('pid')->distinct()->count()
change to
$ad->getcodes()->distinct()->select('pid')->count()
You need to set the values to return as distinct. If you don't set the select fields it will return all the columns in the database and all will be unique. So set the query to distinct and only select the columns that make up your 'distinct' value you might want to add more. ->select('pid','date') to get all the unique values for a user in a day
Based on Laravel docs for raw queries I was able to get count for a select field to work with this code in the product model.
public function scopeShowProductCount($query)
{
$query->select(DB::raw('DISTINCT pid, COUNT(*) AS count_pid'))
->groupBy('pid')
->orderBy('count_pid', 'desc');
}
This facade worked to get the same result in the controller:
$products = DB::table('products')->select(DB::raw('DISTINCT pid, COUNT(*) AS count_pid'))->groupBy('pid')->orderBy('count_pid', 'desc')->get();
The resulting dump for both queries was as follows:
#attributes: array:2 [
"pid" => "1271"
"count_pid" => 19
],
#attributes: array:2 [
"pid" => "1273"
"count_pid" => 12
],
#attributes: array:2 [
"pid" => "1275"
"count_pid" => 7
]
$solution = $query->distinct()
->groupBy
(
[
'array',
'of',
'columns',
]
)
->addSelect(
[
'columns',
'from',
'the',
'groupby',
]
)
->get();
Remember the group by is optional,this should work in most cases when you want a count group by to exclude duplicated select values, the addSelect is a querybuilder instance method.
Wouldn't this work?
$ad->getcodes()->distinct()->get(['pid'])->count();
See here for discussion..
Distinct do not take arguments as it adds DISTINCT in your sql query, however, you MAY need to define the column name that you'd want to select distinct with. Thus, if you have
Flight->select('project_id')->distinct()->get() is equialent to SELECT DISTINCT 'project_id' FROM flights and you may now add other modifiers like count() or even raw eloquent queries.
Use something like this
DB::table('user_products')->select('user_id')->distinct()->pluck('user_id')->toArray();
This was working for me so
Try This:
$ad->getcodes()->distinct('pid')->count()
try this
$ad->getcodes()->groupby('pid')->distinct()->count('pid')
Basically this works
Section::with('fields')->find($id);
also:
Section::with(['fields' => function ($q) {
$q->select('*');
}])->find($id);
however:
Section::with(['fields' => function ($q) {
$q->select('label', 'position');
}])->find($id);
will not load the relations.
I haven't found something in the docs about eager loading constraints except using 'where', so my question is, is this even possible?
Thanks in advance.
Ahh, turns out you have to explicitly include the section_id within the select clause :)
So this will work as expected:
Section::with(['fields' => function ($q) {
$q->select('section_id', 'label', 'position');
}])->find($id);
I had the same problem last days and I couldn't find any solution so now that I have found the solution I would like to share it with anyone who has the same issue.
In order to use the foreign key's in functions, you need to give the function the foreign keys to for the tables so in this case if for example; you want to use section's relation so you need to give the function the values to find the relations so here it is if you have the relation like 'section_id' in fields table you need to use this code:
Section::with(['fields' => function ($q) {
$q->select('id','section_id','label', 'position');
}])->find($id);
also for Laravel 5.7* you can use Eager Loading Specific Columns too as the link below:
enter link description here
I use the response of #iwyg, but the important thing is that the first element inside select is the field that join those tables (foreign Key).
In the example show by #iwyg the table fields join with the table section with the key section_id, thats its why is the first element inside the select. So is not just add the id for make it work
I'm trying to popular a pivot table with ids in a seed.
$id = DB::table('products')->insertGetId(array(
array(
'title' => 'Product A',
'published' => 1
)
));
DB::table('product_user')->insert(array(
array(
'product_id' => $id,
'user_id' => '9999999999'
)
));
Is the above the best way to do it? By getting an id via insertGetId and then putting it in the pivot table Is there a better way?
Also the above way gives an error:
[ErrorException]
preg_replace(): Parameter mismatch, pattern is a string while replacement i
s an array
I suspect $id is an array, how can i get InsertGetId to return an int?
Well, you can print_r it and seek for the id attribute, and then call $id->attribute on the second insert.
But...
"Me myself", I like to use Eloquent. The mainly reason is: 'Cause it too god damm FUN. Really, Eloquent it's one of the most beautful things I've ever seen in the programming world. I use to thought that .NET was a master piece of software (I was young and naive, though) but once a came across Laravel/Eloquent, I became so AMAZED!
That being said, in my humble opinion, use Eloquent is the best way of doing it!
I'm assuming that you have a table called products and another called users, and you have a product_user table to make the connection. Using Eloquent, you can simply do this:
$user = User::find($user_id);
$product = Product::find($product_id);
$product->user->attach($user);
...I reacomend this approach for several reasons, but the first one is: is way more readable.
Well, I hope I ain't been too prolixous on my answer, and that it hope you and others.