Laravel 5 eloquent: select specific column of relation - laravel-5

I have 2 models: Author and Post
In my Post model, I have an author function (One To Many (Inverse)):
public function author()
{
return $this->belongsTo('App\Author', 'author_id');
}
Now I want to export to Excel the following information:
id | title | author name
This is what I tried:
$posts = Post::with(array(
'author' => function ($query) {
$query->select('name');
}))->select('id', 'title')->get();
What I get is an empty author's name column.
What do I wrong?

Since Laravel 5.5 you can use eager loading retrieve multiple specific columns simply by using string
Post::with('author:id,name')->get()
Author::with('posts:id,author_id,title')->get()
Notice the id or foreign key (author_id) must included, or data will be null.

please try:
$posts = Post::with(['author' => function($query){
$query->select(['id','name']);
}])->get(['id','title', 'author_foreign_key_in_posts_table']);
Having that, you'll be able to get:
$posts->first()->author->name;
$posts->first()->id;
$posts->first()->title;
You may use iteration or whatever instead of first() for export.

Related

Get only one column from relation

I have found this: Get Specific Columns Using “With()” Function in Laravel Eloquent
but nothing from there did not help.
I have users table, columns: id , name , supplier_id. Table suppliers with columns: id, name.
When I call relation from Model or use eager constraints, relation is empty. When I comment(remove) constraint select(['id']) - results are present, but with all users fields.
$query = Supplier::with(['test_staff_id_only' => function ($query) {
//$query->where('id',8); // works only for testing https://laravel.com/docs/6.x/eloquent-relationships#constraining-eager-loads
// option 1
$query->select(['id']); // not working , no results in // "test_staff_id_only": []
// option 2
//$query->raw('select id from users'); // results with all fields from users table
}])->first();
return $query;
In Supplier model:
public function test_staff_id_only(){
return $this->hasMany(User::class,'supplier_id','id')
//option 3 - if enabled, no results in this relation
->select(['id']);// also tried: ->selectRaw('users.id as uid from users') and ->select('users.id')
}
How can I select only id from users?
in you relation remove select(['id'])
public function test_staff_id_only(){
return $this->hasMany(User::class,'supplier_id','id');
}
now in your code:
$query = Supplier::with(['test_staff_id_only:id,supplier_id'])->first();
There's a pretty simple answer actually. Define your relationship as:
public function users(){
return $this->hasMany(User::class, 'supplier_id', 'id');
}
Now, if you call Supplier::with('users')->get(), you'll get a list of all suppliers with their users, which is close, but a bit bloated. To limit the columns returned in the relationship, use the : modifier:
$suppliersWithUserIds = Supplier::with('users:id')->get();
Now, you will have a list of Supplier models, and each $supplier->users value will only contain the ID.

Eloquent hasManyThrough also get middle table information

I have same table structure as mentioned in laravel document for HasManyThrough relationship hasManyThrough
countries
id - integer
name - string
users
id - integer
country_id - integer
name - string
posts
id - integer
user_id - integer
title - string
and define a relationship like same as in doc.
public function posts()
{
return $this->hasManyThrough(
'App\Post', 'App\User',
'country_id', 'user_id', 'id'
);
}
Now when I List posts of specific country. I need the information of user of the post too. I mean information from pivot table(users)
$posts = Country::find(2)->posts();
The above returns post data only..
What you need is to eager load the users alongside the posts, can be achieved via the with() method on the Builder:
$posts = Country::find(2)->posts()->with('user')->get();
If you're loading huge amounts of data and don't want the whole User instance loaded, you can even specify which fields to only be retrieved from the users table:
$posts = Country::find(2)->posts()->with('user:id,name')->get();
Then you can simply use $post->user->name or whatever you need when iterating your collection.
Refer to the documentation for more information.
Try this one:
$posts = Country::find(2)->posts()->with('user')->get();

Laravel orm Order by custom attribute

In my user model I have added custom attribute get number of post user have created.
I can successfully get that but when I have try to order by it give error.
1054 Unknown column 'posts' in 'order clause'
Can you let us know what is the Eloquent query you're running? Also make sure that the name of the table you're using is correct.
EDIT:
Does the posts column exist in the users table? Or are you trying to get all the posts from the Post Model and order the posts by their name in descending order?
If that is what you want to do then you would need to go to your User Model and set up your relationship with posts.
In User Model create this method:
public function posts() {
return $this->hasMany('Post'); // Post would be the name of the Posts Model
}
In Post model do this:
public function user() {
return $this->belongsTo('User'); // Where User is the name of the Users Model
}
Then according to the Laravel documentation you could do someonething like this with the query:
$users = User::with(array('posts' => function($query)
{
$query->orderBy('name', 'desc'); // assuming that 'name' would be the column in the posts table you want to sort by
}))->take(5)->get();
I hope I am correct and this helps and that solves your issue.

Laravel 4.2 Eloquent query by relationship column value

Good day to you all...
I'm trying to access a collection based on a column in a related table within Eloquent (Laravel 4.2).
I have the following tables:
tags:
(int) id
(string) name
tag_usage:
(int) id
(string) model (the name of the model that is allowed to use the tag)
tag_tag_usage: (pivot)
(int) id
(int) tag_id
(int) tag_usage_id
I also have a taggables (polymorphic to store tags for multiple models) table which I believe is out of scope here as I only want to retrieve the tags that am allowed to use for each model.
My tag model has the relationship
public function usage()
{
return $this->belongsToMany('TagUsage');
}
and the TagUsage model has
public function tags() {
return $this->belongsToMany('Tag');
}
Now, what I want to do is return the tags that ONLY have a specific usage, some pseudo code would be
get_tags->where(tag_usage.model = modelname)
which would return only a subset of the tags.
Tried a few things with no success so over to the many fine brains available here.
Many thanks.
You need to use whereHas in the following way:
$tags = Tag::whereHas('usage', function($q)
{
$q->whereModel('modelname');
})->get();

Laravel Relationships Conditions - 3 tables

I've got a situation where I've got Posts, Users and Comments.
Each comment stores a post_id and a user_id. What I want to do is get all of a user's comments on a particular post, so that I can do a call like this:
$comments = Auth::User()->comments(post_id=x)->text
(where I know what x is)
I have:
User->HasMany(comments)
Comments->HasOne(User)
Comments->HasOne(Project)
Project->HasMany(comments)
I feel like there needs to be a where or a has or a wherehas or something thrown in.. the best I can manage is that I pull Auth::User()->comments into an array and then search through the array until I find the matching post ID.. that seems wasteful.
with doesn't apply any join, so you can't reference other table.
You can use this:
// User model
public function comments()
{
return $this->hasMany('Comment');
}
// Comment model
public function scopeForPost($query, $postId)
{
$query->where('post_id', $postId);
}
// then you can do this:
Auth::user()->comments()->forPost($postId)->get();
Alternatively you can eager load comments with constraint:
User::with(['comments' => function ($q) use ($postId) {
$q->where('post_id', $postId);
}])->find($someUserId);
// or exactly the same as above, but for already fetched user:
// $user .. or
Auth::user()->load(['comments' => function ($q) use ($postId) {
$q->where('post_id', $postId);
}]);
// then you can access comments for $postId just like this:
Auth::user()->comments; // collection
When you need to filter your relations, you just have to do it in your Eloquent query:
$data = User::with('posts', 'comments')
->where('users.id', Auth::User()->id)
->where('posts.id', $postID)
->get();
Then you can
foreach($data->comments as $comment)
{
echo $comment->text;
}
Your Comments table would have foreign keys Post_Id and User_ID
To Access all the comments of a particular post from a particular user , can you try this way?
Comment::select('comments.*')
->where('comments.user_id', Auth::user()->id)
->leftJoin('posts','posts.id','=','comments.post_id')
->leftJoin('users','users.id','=','comments.user_id')
->get();
Am sure there is better way to achieve it, but this should give you desired results.
Note use aliases if you have conflicting column names
Let me know if this worked.

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