Trying to describe my problem in the title was difficult. What I mean is this. I have 3 tables. Job, Diary, Document.
Each diary entry has a belongsTo relationship with Job. Each Document has a belongsTo relationship with Diary.
How can I query Documents so it returns all the documents belonging to a single job.
Document->diary_id references Diary->id - Diary->job_number_id references Job->id
Both these individual relationships are set up and work.
I have tried different queries with no success.
Any help appreciated.
Regards
Finchy70
Use a HasManyThrough relationship:
public function documents() {
return $this->hasManyThrough(Document::class, Diary::class, 'job_number_id');
}
$documents = $job->documents()->paginate(15);
I have continued to research and try different eloquent queries and have found one that works.
Not sure how economical it is but it does work.
$documents = $job->diary()
->with('job')
->join('documents', 'diary_id', '=', 'diaries.id')
->select(['documents.*'])
->paginate(15);
If anyone has a better solution please share.
Related
I've been using latestOfmany() for my hasMany() relation to define them as hasOne() for quite a while now. Lately I've been in need of the similar application but for belongsToMany() relationships. Laravel doesn't have this feature unfortunately.
My codebase as follows:
Document
id
upload_date
identifier_code
Person
id
name
DocumentPerson (pivot)
id
person_id
person_id
token
My objective is: define relationship for fetching the first document (according to upload_date) of Person. As you can see it's a many-to-many relationship.
What I have tried so far:
public function firstDocument()
{
return $this->hasOne(DocumentPerson::class)->oldestOfMany('document.upload_date');
//this was my safe bet but oldestOfMany() and ofMany() doesn't allow aggregating on relationship column.
}
public function firstDocument()
{
return $this->belongToMany(Document::class)->oldestOfMany('upload_date')
}
public function firstDocument()
{
return $this->belongToMany(Document::class)->oldest()->limit(1);
}
public function firstDocument()
{
return $this->hasOneThrough(Document::class, DocumentPerson::class, 'id', 'document_id', 'id', 'person_id')->latestOfMany('upload_date');
}
At this point I'm almost positive current relationship base doesn't support something like this, so I'm elaborating alternative methods to solve this. My two choices:
Add a column called first_document_id on Person table, go through that with belongsTo() simple and fast performance-wise. But downside is I'll have to implement so many event-listeners to make sure it is always consistent with actual relationships. What if Document's upload_date is updates etc. (basically database inconsistency)
Add a order column on pivot (document_person) table, which will hold order of related Documents by upload_date. This way I can do hasOne(DocumentPerson::class)->oldestOfMany('order');//or just ofMany() and be done with it. This one also poses the risk of database inconsistency.
It's fair to say I'm at a crossroads here. Any idea and suggestion is welcomed and appreciated. Thank you. Please read the restrictions to prevent suggesting things that are not feasible for my situation.
Restrictions:
(Please)
It should strictly be a relationship. I'll be using it on various places, it definitely has to be relationship so I can eager load and query it. My next objective involves querying by this relationship so it is imperative.
Don't suggest accessors, it won't do well with my case.
Don't suggest collection methods, it needs to be done in query.
Don't suggest ->limit() or ->take() or ->first(), those are prone to cause inconsistent results with eager loading.
Update 1
Q: Why first document of a person has to be a relationship ?
A: Because further down the line I'll be querying it in various different instances. Example queries where it'll be utilized:
Get all the users whose first document (according to upload_date) upload_date between 2022-01-01 and 2022-06-08. (along with 10 other scopes and filters)
Get all the users whose first document (according to upload_date) identifier_code starts with "Lorem" and id bigger than 100.
These are just to name a few, there are many cases where I really gotta query it in various fashions. This is the reason that I desperately need it to be a relationship, so I can query it with ease using Person::whereHas('firstDocument',function($subQuery){ return $subQuery->someScope1()->anotherScope2()->where(...); }
If I only needed to display it, yeah sure eager loading with closure would do well, or even collection methods, or accessors would suffice. But since ability to query it is the need, relationship is of the essence. Keep in mind Person table has around 500k record, hence the need for querying it on the database layer.
Alright here's the solution I've elected to go with (among my choices, explained in the question). I implemented the "adding order column on pivot" table. Because it scales better and is rather flexible compared to other options. It allows for querying the last document, first document, third document etc. Whilst it doesn't even require any aggregate functions (Max, min like ->latestOfMany() applies) which is a performance boost. Given these constraints this solution was the way to go. Here's how I applied it in case someone else is thinking about something similar.
Currently the only noticeable downside to this approach is inability to access any additional pivot data.
Added new column for order:
//migration
$table->unsignedTinyInteger('document_upload_date_order')->nullable()->after('token');
$table->index('document_upload_date_order');//for performance
Person.php (Model)
//... other stuff
public function personalDocuments()
{//my old relationship, which I'll still keep for display/index purposes.
return $this->belongsToMany(Document::class)->withPivot('token')->where('type_slug','personal');
}
//NEW RELATIONSHIP
public function firstDocument()
{//Eloquent relationship, allows for querying and eager loading
return $this->hasOneThrough(
Document::class,
DocumentPerson::class,//pivot class for the pivot table
'person_id',
'id',
'id',
'document_id')
->where('document_upload_date_order',1);//magic here
SomeService.php
public function determineDocumentUploadDateOrders(Person $person){
$sortLogic=[
['upload_date', 'asc'],
['created_at', 'asc'],
];
$documentsOrdered=$person->documents->sortBy($sortLogic)->values();//values() is for re-indexing the array keys
foreach ($documentsOrdered as $index=>$document){
//updating through pivot tables ORM model
DocumentPerson::where('id',$document->pivot->id)->update([
'document_upload_date_order'=>$index+1,
'document_id'=>$document->id,
'person_id'=>$document->pivot->person_id,
]);
}
}
I hooked determineDocumentUploadDateOrders() into various event-listeners and model events so whenever association/disassociation occurs, or upload_date of a document changes I simply call determineDocumentUploadDateOrders() with corresponding Person and this way it is always kept in sync with actual.
Implemented it fully and it is providing consistent results with great performance. Of course it brought a bit of an overhead with keeping it in sync. But nonetheless, It did the job whilst meeting the requirements. Honestly I found this approach far more reliable than some in-official eloquent relationships and similar alternatives.
I have encountered a similar situation years back.
the best workaround on a situation like this is to use #staudenmeir package eager limit
Load the trait use \Staudenmeir\EloquentEagerLimit\HasEagerLimit; on both model (parent and related model)
then try the code below
public function firstDocument() {
return $this->documents()->latest()->limit(1);
}
public function documents() {
return $this->belongsToMany(Document::class);
}
just to add, Eager loading with limit does not work with built laravel eloquent, you would have to build your own raw queries to achieve it which can turn into a nightmare. that eager limit package from staudenmeir should have been merge with laravel source code 😆
I am trying to create a "tag cloud" that lists the tag with the most relationships on a many-to-many pivot table schema.
I'm afraid I don't even know what to search in order to begin. I would appreciate any links or code examples, but prefer references so I can learn this once and for all.
I have a table named companies and a table named categories. There is a pivot table named category_company and the proper relationships are setup and working great.
Simply using withCount() should get you there.
$companies = Company::withCount('categories');
Now you are able to access the count like so.
foreach ($companies as $company) {
$company->categories_count; // gives out the count for this companies categories.
}
See the docs.
I have a relationship defined between users and permisson, a user can have many permissions.
When I use "with" I get the data normally.
$user->with('permisson')->get();
I get the user with their permissions.
When I use "has" it only returns the user.
$user->has('permission')->get();
For what I've read, I should get the permissons if the user contains at least one permission.
I am using Postgres driver.
with is used for eager loading a relationship. You'd use it to fetch all of the specified relationships for each model (individually, or in a collection).
has is for using the relationship as a constraint or filter. As you said, using something like has('permission') will add a constraint to the query that says "only get Users that have at least one permission". This does not automatically load the relations like with(), it only creates the constraint.
You can combine the two if you want to take advantage of both the constraint and eager loading the results.
User::has('permission')->with('permission')->get();
Seems a bit redundant, I know.
From laravel docs:
If you wish to limit your results based on the existence of a relationship, you should use the has method. For example, if you want to retrieve all blog posts taht have at least one comment, yo may pass the name of the relationship to the has and orHas methods:
$posts = Post::has('comments')->get();
So, when you use the has method, it will not return the relationship, but just the post models which has at least one comment.
The whereHas and orWhereHas methods allows you to add customized constraints to a relationship constraint, such as checking the content of a comment (using the laravel example):
$posts = App\Post::whereHas('comments', function (Builder $query) {
$query->where('content', 'like', 'foo%');
})->get();
When you use the with method, you are loading the realtionship with the model:
$user->with('permission')->get()
This code will load the user and the permission relationship, while this one
$user->has('permission')->get();
will load the user who has some permission.
Hope it helps.
Lets say I have three models: Post, Category and Tag.
The Post belongsTo Category and Category hasMany Post.
Theres manyToMany relation between Tag and Category.
I want to list my posts by Category name and paginate the results.
Post::with('category','category.tags')
->orderBy('category.name') //this is the bogus line
->paginate(10);
But this syntax doesn't work.
What I tried is this as:
Post::select('categories.*')
->join('categories','posts.category_id','=','categories.id')
->orderBy('categories.name)
->paginate(10);
But then I lose the eager loaded data.
If I drop the select() clause then I get rubbish data as categories.id overwrites posts.id. See here.
Is there any elegant way to solve this issue? After spending hours on this I'm one step away from iterating through paginated posts and 'manually' loading the relations as:
foreach($posts as $post) {
$post->load('category','category.tags');
}
Not even sure if there's downside to this but it doesn't seem right. Please correct me if I'm wrong.
UPDATE on last step: Eager loading on paginated results won't work so if I go that road I'll need to implement even uglier fix.
You should be able to use both join and with.
Post::select('posts.*') // select the posts table fields here, not categories
->with('category','category.tags')
->join('categories','posts.category_id','=','categories.id')
->orderBy('categories.name)
->paginate(10);
remember, the with clause does not alter your query. Only after the query is executed, it will collect the n+1 relations.
Your workaround indeed loses the eager loading benefits. But you can call load(..) on a collection/paginator (query result) as well, so calling ->paginate(10)->load('category','category.tags') is equivalent to the query above.
I'm a bit confused about how to do the following.
I have a table of articles and a table of tags with a many to many join and a pivot table between the two. I've got the relationships set up in the models
An articles can have more than one tag.
How can I easily(?) obtain a list of related articles for an article based on the tags attached to the current article.
I've tried querying from the tags side as follows:
foreach($article->tags()->get() as $tag) {
$relatedArticles .= Tag::with('articles')
->where('id','=', $tag->id)
->take(6)
->get();
}
This produces a nil response
I'm not sure about how to query from the articles to find articles with the tags dynamically.
So if an article has attached tag1 and tag2 I then want to retrieve all articles which have either tag1 or tag2 attached to them (ideally sorted on article date). The tags will be different for each article and may just be one or many.
Ideally i'd like to do this with an eloquent query but not essential - I'm not sure how to do in mysql either as a starting point.
Any help appreciated
Provided you are using Laravel 4.1, you can do something like this using the whereHas eloquent method:
$tag_ids = $article->tags()->lists('id');
$relatedArticles = Article::whereHas('tags', function($q) use ($tag_ids) {
$q->whereIn('id', $tag_ids);
})
->orderBy('created_at')
->take(6)
->get();
Breakdown
There's a few things going on here:
lists()
You can use the lists method on a select to get just a particular column, we're only concerned with the ID column in this case.
More info here: http://laravel.com/docs/queries#selects
whereHas()
We're using the new whereHas method which you can read.
More more about here: http://laravel.com/docs/eloquent#querying-relations
use()
Since the whereHas method accepts a closure (or 'anonymous function'), the function doesn't have any access to variables set externally, so we need to send them through to the function. We can do this with use.
More information here: http://www.php.net/manual/en/functions.anonymous.php