如何：验证 Laravel 4 中数据库关系的存在？
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How to: validate the existence of a database relationship in Laravel 4?
提问by koosa
I have a model Productthat belongs to a Trend:
我有一个Product属于a 的模型Trend：
class Product extends Eloquent {
public function trend()
{
return $this->belongsTo('Trend');
}
}
And as part of my validation rules I would like to check that this relationship exists, and if not trigger an error using:
作为验证规则的一部分，我想检查这种关系是否存在，如果不存在，则使用以下方法触发错误：
$validator = Validator::make(Input::all(), $rules, $messages);
if ($validator->fails())
{
... some redirection code here
is called. I have tried to use the validation existslike below, but it never fires.
叫做。我曾尝试使用如下所示的验证存在，但它永远不会触发。
$rules = array(
'brand_name' => 'required|min:3',
'blurb' => 'required',
'link' => 'required',
'trend' => 'exists:trends'
);
I have also tried a few variations on the existsmethod, but nothing ever seems to fire. I know that the instance I am testing on definitely doesn'thave a relationship set.
我还尝试了该exists方法的一些变体，但似乎没有任何效果。我知道我正在测试的实例肯定没有关系集。
What am I doing wrong here?
我在这里做错了什么？
EDIT: I see now from typing this out that I am validating the inputand not the models values. How would I actually validate a model instance's properties instead?
编辑：我现在从输入中看到我正在验证输入而不是模型值。我将如何实际验证模型实例的属性？
回答by Rubens Mariuzzo
I have the following code in a ExchangeRateclass:
我在一个ExchangeRate类中有以下代码：
/**
* Return the validator for this exchange rate.
*
* @return Illuminate\Validation\Validator A validator instance.
*/
public function getValidator()
{
$params = array(
'from_currency_id' => $this->from_currency_id,
'to_currency_id' => $this->to_currency_id,
'valid_from' => $this->valid_from,
'rate' => $this->rate,
'organization_id' => $this->organization_id,
);
$rules = array(
'from_currency_id' => ['required', 'exists:currencies,id'],
'to_currency_id' => ['required', 'exists:currencies,id', 'different:from_currency_id'],
'valid_from' => ['required', 'date'],
'rate' => ['required', 'numeric', 'min:0.0'],
'organization_id' => ['required', 'exists:organizations,id'],
);
return Validator::make($params, $rules);
}
Of course, this ExchangeRateclass also have the associations defined:
当然，这个ExchangeRate类也定义了关联：
public function from_currency()
{
return $this->belongsTo('Currency', 'from_currency_id');
}
public function to_currency()
{
return $this->belongsTo('Currency', 'to_currency_id');
}
And all this glued together works like a clock:
所有这些粘合在一起就像一个时钟：
$validator = $exchangeRate->getValidator();
if ($validator->fails())
throw new ValidationException($validator);
