blocks|key|83687|text|你可能想要这样的东西：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|83688|$user_favorites+=+DB::table('user_favorites')
++++->where('user_id',+'=',+Auth::user()->id)
++++->where('item_id',+'=',+$item->id)
++++->first();

if+(is_null($user_favorites))+{
++++//+It+does+not+exist+-+add+to+favorites+button+will+show
}+else+{
++++//+It+exists+-+remove+from+favorites+button+will+show
}|code-block|syntax|javascript|83689|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You may want something like this:

<pre><code>$user_favorites = DB::table('user_favorites')
 -&gt;where('user_id', '=', Auth::user()-&gt;id)
 -&gt;where('item_id', '=', $item-&gt;id)
 -&gt;first();

if (is_null($user_favorites)) {
 // It does not exist - add to favorites button will show
} else {
 // It exists - remove from favorites button will show
}
</code></pre>

blocks|key|83706|text|假设User_favorite是一个访问user_favorites表的模型|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|83707|$result+=+User_favorite::where('user_id',Auth::getUser()->id)
+++++++++++++++++++++++++->where('item_id',$item->id)
+++++++++++++++++++++++++->first();

if+(is_null($result))+{
//+Not+favorited+-+add+new
++++User_favorite::create(['user_id'=>Auth::getUser()->id,'item_id'=>$item->id]);
}+else+{
//+Already+favorited+-+delete+the+existing
++++$result->delete();
}|code-block|syntax|javascript|83708|entityMap^0|2|D|K|E|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Let <code>User_favorite</code> be a model that accesses your <code>user_favorites</code> table

<pre><code>$result = User_favorite::where('user_id',Auth::getUser()-&gt;id)
 -&gt;where('item_id',$item-&gt;id)
 -&gt;first();

if (is_null($result)) {
// Not favorited - add new
 User_favorite::create(['user_id'=&gt;Auth::getUser()-&gt;id,'item_id'=&gt;$item-&gt;id]);
} else {
// Already favorited - delete the existing
 $result-&gt;delete();
}
</code></pre>

blocks|key|83750|text|我建议您使用exists()或count()进行检查，而不是使用first()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|83751|最快的方法：|83752|$result+=+DB::table('user_favorites')
++++->where('user_id',+'=',+Auth::user()->id)
++++->where('item_id',+'=',+$item->id)
++++->exists();|code-block|syntax|javascript|83753|或者：|83754|$result+=+DB::table('user_favorites')
++++->where('user_id',+'=',+Auth::user()->id)
++++->where('item_id',+'=',+$item->id)
++++->count();|83755|SQL：|83756|select+count(*)+as+aggregate+from+`user_favorites`+where+***+limit+1|83757|更快的方法:只选择id|83758|$result+=+DB::table('user_favorites')
++++->where('user_id',+'=',+Auth::user()->id)
++++->where('item_id',+'=',+$item->id)
++++->first(['id']);|83759|83760|select+id+from+`user_favorites`+where+***+limit+1|83761|正常方式：|83762|$result+=+DB::table('user_favorites')
++++->where('user_id',+'=',+Auth::user()->id)
++++->where('item_id',+'=',+$item->id)
++++->first();|83763|83764|select+*+from+`user_favorites`+where+***+limit+1|83765|entityMap^0|6|8|F|7|W|7|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1H|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1I|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1J|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1K|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1L|8|@]|D|@]|E|$]]|$1|S|3|T|5|J|7|1M|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1N|8|@]|D|@]|E|$]]|$1|W|3|X|5|J|7|1O|8|@]|D|@]|E|$K|L]]|$1|Y|3|R|5|6|7|1P|8|@]|D|@]|E|$]]|$1|Z|3|10|5|J|7|1Q|8|@]|D|@]|E|$K|L]]|$1|11|3|12|5|6|7|1R|8|@]|D|@]|E|$]]|$1|13|3|14|5|J|7|1S|8|@]|D|@]|E|$K|L]]|$1|15|3|R|5|6|7|1T|8|@]|D|@]|E|$]]|$1|16|3|17|5|J|7|1U|8|@]|D|@]|E|$K|L]]|$1|18|3|-4|5|6|7|1V|8|@]|D|@]|E|$]]]|19|$]]

I advise you to use <code>exists()</code> or <code>count()</code> to check, not use <code>first()</code>.

The fastest way:

<pre><code>$result = DB::table('user_favorites')
 -&gt;where('user_id', '=', Auth::user()-&gt;id)
 -&gt;where('item_id', '=', $item-&gt;id)
 -&gt;exists();
</code></pre>

Or:

<pre><code>$result = DB::table('user_favorites')
 -&gt;where('user_id', '=', Auth::user()-&gt;id)
 -&gt;where('item_id', '=', $item-&gt;id)
 -&gt;count();
</code></pre>

SQL:

<pre><code>select count(*) as aggregate from `user_favorites` where *** limit 1
</code></pre>

The faster way: only select id

<pre><code>$result = DB::table('user_favorites')
 -&gt;where('user_id', '=', Auth::user()-&gt;id)
 -&gt;where('item_id', '=', $item-&gt;id)
 -&gt;first(['id']);
</code></pre>

SQL:

<pre><code>select id from `user_favorites` where *** limit 1
</code></pre>

The normal way:

<pre><code>$result = DB::table('user_favorites')
 -&gt;where('user_id', '=', Auth::user()-&gt;id)
 -&gt;where('item_id', '=', $item-&gt;id)
 -&gt;first();
</code></pre>

SQL:

<pre><code>select * from `user_favorites` where *** limit 1
</code></pre>

I have the following db structure:

<pre><code>items:
id, name, user_id

users table:
id, name

user_favorites table:
id, user_id, item_id
</code></pre>

On my items permalink pages, I have an 'Add to favorites' button which inserts a new row into <code>user_favorites</code>

I want to be able to replace it for a 'Remove from favorites' button if the user already has it in their favorites.

I can't figure out the logic behind this - do I need to check if a row exists in <code>user_favorites</code> that has the current user's id and the permalink item id? This did not work for me:

<pre><code>if (Auth::user()-&gt;id) {
 if (!is_null(DB::table('user_favorites')-&gt;where('user_id', '=', Auth::user()-&gt;id)-&gt;where('item_id', '=', $item-&gt;id)-&gt;first())) {
 // remove from favorites button will show
 }
}
</code></pre>

Check if row exists, Laravel

我有以下db结构：items:id, name, user_idusers table:id, nameuser_favorites table:id, user_id, item_id在我的项目固定链接页面上，我有一个‘添加到收藏夹’按钮，它会在user_favorites中插入一个新的行我想能够将它替换为“从收藏夹...

问检查行是否存在，Laravel
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