Laravel Eloquent 关系与多个带有“OR”的外键

Question

我有模型Account，账户有交易-模型Transactions。

在 Transactions 我有两个外键 - from_account_id 和 to_account_id 都与 Account 模型相关。

现在我想在这两个模型之间创建关系（例如... WHERE transactions.from_account_id = accounts.id OR transactions.to_account_id = accounts.id），但 Eloquent 不支持关系上的两个外键。

我找到了topclaudy/compoships这个包，但是不支持OR

有什么解决办法吗？

Answer 1

在两个外键上定义关系从逻辑上讲是没有意义的。在您的用例中，逻辑关系将是

class Account extends Model
{
    public function outwardTransactions()
    {
        return $this->hasMany(Transaction::class, 'from_account_id');
    }

    public function inwardTransactions()
    {
        return $this->hasMany(Transaction::class, 'to_account_id');
    }
 
    public function allTransactions()
    {
        return $this->outwardTransactions->concat($this->inwardTransactions);
    }

    //Or a local scope on model to get all transactions
    public function scopeWithAllTransactions($query)
    {
        return $query->with(['outwardTransactions', 'inwardTransactions']);
    }
}

Transaction 模型上的关系可以定义为

class Transaction extends Model
{
    public function sourceAccount()
    {
        return $this->belongsTo(Account::class, 'from_account_id', 'id');
    }

    public function destinationAccount()
    {
        return $this->belongsTo(Account::class, 'to_account_id', 'id');
    }

    public function accounts()
    {
        return collect([$this->sourceAccount, $this->destinationAccount]);
    }

    //Or a local scope on model to get all accounts
    public function scopeWithAllAccounts($query)
    {
        return $query->with(['sourceAccount', 'destinationAccount']);
    }
}

多对多关系

为了接近您想要实现的目标，一种方法是使用 Account 和 Transaction 模型之间的多对多关系，因为在逻辑上

• 一笔交易有很多账户（每笔交易有两个账户）
• 一个账户（可以有）hasMany Transaction(s)

会有一个中间链接表account_transaction，上面会有一个额外的列type，可以包含credit或debit作为值。

//account_transaction table
public function up()
{
     Schema::create('account_transaction', function (Blueprint $table) {
        $table->id();
        $table->foreignId('account_id')->constrained();
        $table->foreignId('transaction_id')->constrained;
        $table->enum('type', ['debit', 'credit']);
        $table->timestamps();

        $table->unique(['account_id', 'transaction_id']);

    });
}

//transactions table
public function up()
{
     Schema::create('transactions', function (Blueprint $table) {
        $table->id();
        $table->unsignedInteger('amount');
        //any other columns...
        $table->timestamps();

    });
}

那么关系可以定义为

class Account extends Model
{
    public function transactions()
    {
        return $this->belongsToMany(Transaction::class)
            ->withPivot('type')
            ->withTimestamps();
    }

    //... rest of the class code
}

class Transaction extends Model
{
    public function accounts()
    {
        return $this->belongsToMany(Account::class)
            ->withPivot('type')
            ->withTimestamps();
    }

    //... rest of the class code
}

唯一的问题是，在为交易创建条目时，您需要在 account_transaction 表中创建两个对应的条目 - 一个用于具有 debit 类型的 from_account，另一个用于to_account 带有 credit 类型

//Example transaction:
//FromAccountId = 5
//ToAccountId = 20
//Amount = $100

$transaction = Transaction::create(['amount' => 10000]); //100$ x 100 = 10000 cents in database
$transaction->accounts()->attach([
    5 => ['type' => 'debit'],
    20 => ['type' => 'credit'],
]);

然后您可以根据需要执行各种查询，也可以查询关系存在has，whereHas

$creditTransactions = $account->transactions()->wherePivot('type', 'credit')->get();

$currentDayTransactions = $account->transactions()->whereDate('created_at', now())->get();