约束渴望的关系 [英] Constraining eager loaded relationship

问题描述

我发现with函数的异常行为使关系超载.我有Product和Deal关系，例如Product belongsTo() Deal(通过deals表中的product_id).现在，当我尝试出售所有产品时:

I found a very bizarre behavior of with function for overloading relationships. I have Product and Deal relationships, such that Product belongsTo() Deal (through product_id in deals table). Now, when I try to get all products on sale:

Product::with(['deal' => function($query) {
    $query->whereDate('ends_at', '>', Carbon::now()->toDateTimeString());
}])->get()

这将返回所有产品的集合，即使deals表中没有没有记录并且所有产品具有deal_id设置为NULL.同时，如您所料，Product::has('deal')->get()返回一个空集合.

this returns a collection of all products, even though there are no records in deals table and all products have deal_id set to NULL. At the same time Product::has('deal')->get() returns an empty collection, as you would expect.

我最初是在尝试获取五种随机产品以及Deal和Image关系的时候发现这个问题的:

I initially discovered this problem while trying to fetch five random products on sale together with Deal and Image relationships:

Product::with(['deal' => function ($query) {
        $query->whereDate('ends_at', '>', // promo still active
                             Carbon::now()->toDateTimeString());
    },
    'images' => function ($query) {
        $query->where('featured', true);    // image featured on homepage
    }])
->where('status', 'IN_STOCK')   // 'In Stock'
->whereNull('deleted_at')       // wasn't soft-deleted
->orderByRaw('RAND()')
->take(5)->get())

这将产生一个集合，其中所有Product中有5个随机Product.我尝试使用query->whereNotNull('ends_at')->whereDate('ends_at' ..... );，但得到了相同的结果.

This yields a collection with 5 random Products out of all Products. I tried with query->whereNotNull('ends_at')->whereDate('ends_at' ..... ); but got same results.

我在做什么错了?

推荐答案

您对此概念的理解完全是错误的.

Your understanding of the concept is completely wrong here.

如果您说的是产品 belongsTo() 交易，那么假设交易 hasMany() 产品.

If you are saying that a Product belongsTo() Deal, then lets assume that a Deal hasMany() Products.

这是特价表

deals
id | name | ends_at | blah | blah

products
id | deal_id | name | blah | blah

因此，基本上Product::with('deal')应该会向您返回所有其交易均已热切加载的产品.但是Deal::with('products')将返回一个空集合，因为其中没有产品包含有效的deal_id.

So basically, the Product::with('deal') should return you all products with their Deals being Eager loaded. But Deal::with('products') will return you an empty collection, since no products have a valid deal_id in it.

请注意，由于产品只能belongTo单个交易，因此在执行Product::with('deal')查询.但是，当您执行Deal::with('products')时，您必然会得到一个集合.

It is important to note that, since Product can only belongTo a single Deal, you will always get the Deal Model rather than a collection when you perform Product::with('deal') query. But when you perform Deal::with('products') you are bound to get a collection.

所以基本上，当你说

这将返回所有产品的集合，即使在交易表中没有记录并且所有产品的deal_id都设置为NULL.

This returns a collection of all products, even though there are no records in deals table and all products have deal_id set to NULL.

这很明显 ....，因为此处的查询是针对产品"而不是交易"进行的.如果要在ends_at > Carbon::now()所在的位置找到交易，则必须这样做.

It is pretty obvious.... because the query here is being done on Products and not Deal. If you are trying to find the Deal where ends_at > Carbon::now(), you'll have to do this.

Deal::with('product')->where('ends_at', '>', Carbon::now()->toDateTimeString())

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