如果数据库中存在值，请不要保存Laravel

Question

我正在创建一个愿望清单，用户可以在其中保存自己的产品并保存。 我想要的是用户不能多次保存产品。 因此，我正在做的是，如果product_id存在于数据库中，则我不想保存新记录。

这是我的代码，我在做什么错？

public function addWishlist(Wishlist $wishlist) {        
    $wishlist->user_id = request('user_id');
    $wishlist->product_id = request('product_id');

    if(DB::table('wishlists')->where('product_id' !== $wishlist->product_id)) {
        $wishlist->save();
        return redirect()->back();
    }
}

Answer 1

那这个呢

public function addWishlist(Wishlist $wishlist) {  
    $userId = request('user_id');
    $productId = request('product_id');

    $found = Wishlist::where('user_id', $userId)->where('product_id', $productId)->count();

    if($found == 0) {
        $wishlist->user_id = $userId;
        $wishlist->product_id = $productId;
        $wishlist->save();
        return redirect()->back();
    }
}

Answer 2

public function addWishlist(Wishlist $wishlist) {   

    if(DB::table('wishlists')->where(['user_id'=>$user_id,'product_id'=>$wishlist->product_id])->exists()){
         // record already exist 
         return redirect()->back();
    }else{
         // record not exist , save the record
         $withlist = new Wishlist();     
         $wishlist->user_id = request('user_id');
         $wishlist->product_id = request('product_id');
         $wishlist->save();
         return redirect()->back();
    }
}

Answer 3

您可以使用firstOrNew并且需要使用user_id和product_id组合进行检查

    $wishlist::firstOrNew(array('user_id' => request('user_id'),'product_id'=>request('product_id')));
    $wishlist->user_id = request('user_id');
    $wishlist->product_id = request('product_id');
    $wishlist->save();
    return redirect()->back();

Answer 4

您是否尝试过FirstOrCreate（）

 $user = User::firstOrCreate(['email' => $email])