因為過節，產品頁面分三天寫；
後續依狀況會回頭整併在一起。

• 修改Repository

 public Repository(ApplicationDbContext db)
        {
            _db = db;
            this.dbSet = _db.Set<T>();
            _db.Products.Include(u => u.Category).Include(u => u.CategoryId);
        }

 public T Get(Expression<Func<T, bool>> filter, string? includeProperties = null)
        {
            IQueryable<T> query = dbSet;
            query = query.Where(filter);
            if (!string.IsNullOrEmpty(includeProperties))
            {
                foreach (var includeProp in includeProperties.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries))
                {
                    query = query.Include(includeProp);
                }
            }
            return query.FirstOrDefault();
        }

 public IEnumerable<T> GetAll(Expression<Func<T, bool>>? filter, string? includeProperties = null)
        {
            IQueryable<T> query = dbSet;
            if (filter != null)
            {
                query = query.Where(filter);
            }
            if (!string.IsNullOrEmpty(includeProperties))
            {
                foreach (var includeProp in includeProperties.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries))
                {
                    query = query.Include(includeProp);
                }
            }
            return query.ToList();
        }

• 修改IRpeository

IEnumerable<T> GetAll(Expression<Func<T, bool>>? filter = null, string? includeProperties = null);
T Get(Expression<Func<T, bool>> filter, string? includeProperties = null);

• 修改UnitOfWork
  IUnitOfWork與UnitOfWork都要新增Product後微調程式。

 public IProductRepository Product { get; private set; }

Product = new ProductRepository(_db);

• 修改IUnitOfWork

 IProductRepository Product { get; }

• Product新增CURD
  1.複製View底下Category資料夾，修改資料夾名稱為Product。
  2.將Product底下的Upsert、Index.cshtml打開，
  選取Category=>Ctrl+Shift+F 用 Product 針對開啟的文件取代即可。
  3.取代完畢後，依照Product的Model修改View。

• Product/Index.cshtml

<table id="productTbl" class="table">

 <thead>
        <tr>
<th>
@Html.DisplayNameFor(model => model.Name)
</th>
<th>
@Html.DisplayNameFor(model => model.Category.Name)
</th>
<th>
@Html.DisplayNameFor(model => model.Size)
</th>
<th>
@Html.DisplayNameFor(model => model.Price)
</th>
<th>
@Html.DisplayNameFor(model => model.Description)
</th>
<th>Action</th>
        </tr>
    </thead>

 <td>
@Html.DisplayFor(modelItem => item.Name)
</td>
<td>
@Html.DisplayFor(modelItem => item.Category.Name)
</td>
<td>
@Html.DisplayFor(modelItem => item.Size)
</td>
<td>
@Html.DisplayFor(modelItem => item.Price)
</td>
<td>
@Html.DisplayFor(modelItem => item.Description)
</td>