代码之家 › 专栏 › 技术社区 › Stian

如何根据不同对象类型的另一个列表从数据库中获取列表?

entity-framework-core linq c#

1

Stian · 技术社区 · 7 年前

我有这两种型号:

public class Product
{
    public int Id { get; set; }
    public int ProductGroupId { get; set; }
    public int ProductGroupSortOrder { get; set; }
    // ... some more properties
    public ICollection<ProductInCategory> InCategories { get; set; }
}

public class ProductInCategory
{
    public int Id { get; set; }
    public int ProductId { get; set; }
    public int ProductCategoryId { get; set; }
    public int SortOrder { get; set; }

    // Nav.props.:
    public Product Product { get; set; }
    public ProductCategory ProductCategory { get; set; }
}

一些 Product s通过属性分组在一起 ProductGroupId 我希望能够删除 产品 来自于 ProductInCategory 在单个数据库查询中。

控制器方法接收 product_id 和A category_id ,不是 产品组ID .

单人间的 产品 我已使用此查询将其从类别中删除:

ProductInCategory unCategorize = await _context.ProductsInCategories
    .Where(pic => pic.ProductId == product_id && pic.ProductCategoryId == category_id)
    .FirstOrDefaultAsync();

然后:

_context.Remove(unCategorize);
await _context.SaveChangesAsync();

现在,如果我有 List<Product> 我想从中删除的 ProductsInCategories ,查询将是什么样的?

我试过了,但是失败了 .Any() -位:

Product product = await _context.Products
    .Where(p => p.Id == product_id)
    .FirstOrDefaultAsync();

List<Product> products = await _context.Products
    .Where(g => g.ProductGroupId == product.ProductGroupId)
    .ToListAsync();

List<ProductInCategory> unCategorize = await _context.ProductsInCategories
    .Where(pic => pic.ProductId == products.Any(p => p.Id)
        && pic.ProductCategoryId == category_id)
    .ToListAsync();

4 回复 | 直到 7 年前

1

2

Ivan Stoev 7 年前

product_id category_id ProductGroupId

int? productGroupId = await _context.Products
    .Where(p => p.Id == product_id)
    .Select(p => (int?)p.ProductGroupId)
    .FirstOrDefaultAsync();

if (productGroupId == null)
{
    // Handle non existing product_id 
}

Product

List<ProductInCategory> unCategorize = await _context.ProductsInCategories
    .Where(pic => pic.Product.ProductGroupId == productGroupId)
    .ToListAsync();

2

1

Ajay Gupta 7 年前

List<ProductInCategory> unCategorize = await _context.ProductsInCategories
    .Where(pic => products.Select(p => p.Id).Contains(pic.ProductId)
        && pic.ProductCategoryId == secondary_id)
    .ToListAsync();

3

1

Flater 7 年前

DELETE FROM People WHERE Name = 'Bob'

context.Database.ExecuteSqlCommand(
        "DELETE FROM Products WHERE ProductGroupId = " + product.ProductGroupId 
      );

product.ProductGroupId

Entity Framework Extensions

context.Customers.Where(x => x.ID == userId).DeleteFromQuery();

_context.Products.Where(g => g.ProductGroupId == product.ProductGroupId).DeleteFromQuery();

4

0

Sachila Ranawaka 7 年前

products

.Where(pic => products && pic.ProductId == products.Any(p => p.Id)
    && pic.ProductCategoryId == secondary_id)