Eloquent与条件有很多关系

Question

I have a model Contract with properties 'id', 'orderer_user_id' and 'contractor_user_id'. I have a model Signature with properties 'contract_id', 'user_id' and 'signed'. I have a hasMany relationship on Contract to retrieve the Signatures belonging to the contract. Each Contract has two Signatures, one belonging to the orderer, the other to the contractor.

I need to get all Contracts that have its orderer signatures not yet signed (so 'contract_id' has to be the id of its parent, 'user_id' has to be the 'orderer_user_id' of its parent and 'signed' has to be false)

What's the Laravel/Eloquent way to achieve this? I understand I can just code a foreach loop and iterate all contracts, check its signatures and then build a collection of contracts with unsigned orderer signatures but it feels clumsy. I've been playing around with relationships/has/doesnthave etc. but I can't seem to get the correct results.

Answer 1

You should have the relation implemented on Contract model

// Contract.php

public function signatures() {
    // add proper parameters 2nd: foreign key and 3rd: local key if 
    // your Database design is not respecting laravel/eloquent naming guidelines
    return $this->hasMany(Signature::class); 
}

In order to retrieve the unsigned Contracts this should work:

$unsignedContracts = Contract::whereHas("signatures", '<', 2)->get();    

I think this should also cover no entries at all, but in case it does not, you can also try this

$unsignedContracts = Contract::whereDoesntHave("signatures")
                             ->orWhereHas("signatures", '<', 2)->get();

If you want to query all signatures with an additional condition this is also possible:

$unsignedContracts = Contract::whereHas("signatures", function($q) {
                         $q->where("signed","=",false);
                     })->get()

You can also introduce concrete relations for contractor and orderer in the Signature model:

// Signature.php

public function contractor() {
    return $this->belongsTo(User::class, "contractor_user_id", "id"); 
}

public function orderer() {
    return $this->belongsTo(User::class, "orderer_user_id", "id"); 
}

With these you should be able to do this:

// this should return all contracts where one of the 
// required users has not signed yet
$unsignedContracts = Contract::where(function($q) {
    $q->whereDoesntHave("contractor")
      ->orWhereDoesntHave("orderer");
})->get();

Laravel documentation is pretty nice imho, have a look on
https://laravel.com/docs/5.6/eloquent-relationships#querying-relations for more input.

Answer 2

You can either create a cope or define on your multiple relationship what you wish to be whenever you call it (add a ->where()->select()...).

Personally, I'd make a scope so you can just call the relationship whenever you want and just apply scopes whenever needed, making both functions (that's what they are in the end, functions) to be independent.

https://laravel.com/docs/5.6/eloquent#local-scopes