C# 实体框架-根据子实体条件筛选和检索子实体
我的问题如下：我有一个C# 实体框架-根据子实体条件筛选和检索子实体,c#,asp.net,.net,entity-framework,.net-core,C#,Asp.net,.net,Entity Framework,.net Core,我的问题如下：我有一个产品实体，如下所示： public int Id { get; set; } public string Title { get; set; } public decimal Price { get; set; } public string Excerpt { get; set; } public string Description { get; set; } public virtual Category Category { get; set; } public D
产品public int Id { get; set; }
public string Title { get; set; }
public decimal Price { get; set; }
public string Excerpt { get; set; }
public string Description { get; set; }
public virtual Category Category { get; set; }
public DateTime Published { get; set; }
public string[] Tags { get; set; }
public int PublisherId { get; set; }
public virtual User Publisher { get; set; }
public virtual ICollection<MyImage> Images { get; set; }
public async Task<PagedList<Product>> GetProducts(UserParams userParams)
{
var productsFromRepo = context.Products
.Select(p => new {
Product = p,
Images = p.Images.Where(i => i.IsMain)
})
.OrderByDescending(b => b.Product.Published);
var productsToReturn = productsFromRepo.Select(i => i.Product).AsQueryable();
return await PagedList<Product>.CreateAsync(productsToReturn, userParams.PageNumber, userParams.PageSize);
}
[
{
"id": 2,
"title": "My First Product",
"description": "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.",
"category": "Uncategorized",
"price": 15.0,
"excerpt": "Lorem ipsum",
"tags": [
"Tag1",
"Tag2"
],
"images": [
{
"id": 1,
"description": "test",
"isMain": true,
"dateAdded": "2020-07-15T22:40:09.285481",
"image":"/9j/...."
},
{
"id": 2,
"description": "test1",
"isMain": false,
"dateAdded": "2020-07-15T23:15:44.74166",
"image":"/9j/...."
},
{
"id": 3,
"description": "test1",
"isMain": false,
"dateAdded": "2020-07-15T23:27:39.636685",
"image":"/9j/...."
}
],
"published": "2020-07-15T22:39:27.89482",
"publisher": {
"id": 1,
"name": null,
"lastName": null,
"email": "testemail@gmail.com"
}
}
]
[
{
"id": 2,
"title": "My First Product",
"description": "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.",
"category": "Uncategorized",
"price": 15.0,
"excerpt": "Lorem ipsum",
"tags": [
"Tag1",
"Tag2"
],
"images": [
{
"id": 1,
"description": "test",
"isMain": true,
"dateAdded": "2020-07-15T22:40:09.285481",
"image":"/9j/...."
},
],
"published": "2020-07-15T22:39:27.89482",
"publisher": {
"id": 1,
"name": null,
"lastName": null,
"email": "testemail@gmail.com"
}
}
]
提前感谢不要在产品上选择，而是尝试在图像上选择：
public async Task<PagedList<Product>> GetProducts(UserParams userParams)
{
var productsFromRepo = context.Images
.Where(i => i.IsMain)
.Select(i => new Product {
Id = i.Product.Id,
Title = i.Product.Title,
...
Images = new List<Image>{ i }
})
.OrderByDescending(b => b.Published)
.AsQuerable();
return await PagedList<Product>.CreateAsync(productsFromRepo, userParams.PageNumber, userParams.PageSize);
}
不要在产品上选择，而是尝试在图像上选择：
public async Task<PagedList<Product>> GetProducts(UserParams userParams)
{
var productsFromRepo = context.Images
.Where(i => i.IsMain)
.Select(i => new Product {
Id = i.Product.Id,
Title = i.Product.Title,
...
Images = new List<Image>{ i }
})
.OrderByDescending(b => b.Published)
.AsQuerable();
return await PagedList<Product>.CreateAsync(productsFromRepo, userParams.PageNumber, userParams.PageSize);
}
在我看来，匿名对象没有任何帮助。您可以在从数据库检索产品图片后对其进行过滤，或者如果要阻止EF将其从数据库中取出，请使用查询过滤器 检查此项以获得清晰的图片 这样做的目的是在pictures实体的fluent api配置中包括查询过滤器：
builder.HasQueryFilter(p => p.IsMain);
.IgnoreQueryFilters()
另外，我没有包含完整的代码片段，如果您觉得没有意义，请让我演示完整的代码。嗯，我认为匿名对象没有帮助。您可以在从数据库检索产品图片后对其进行过滤，或者如果要阻止EF将其从数据库中取出，请使用查询过滤器 检查此项以获得清晰的图片 这样做的目的是在pictures实体的fluent api配置中包括查询过滤器：
builder.HasQueryFilter(p => p.IsMain);
.IgnoreQueryFilters()
另外，我没有包含完整的代码片段，如果您觉得没有意义，请让我演示完整的代码。实体反映数据状态，而仅反映数据状态。如果您想为视图筛选结果，这是一个单独的问题。不要将实体发送到视图，而是将ViewModels发送到视图。视图模型将表示视图所需的数据，并且仅表示视图所需的数据，即视图所期望的方式。实体暴露了太多关于域模型的信息，如果服务器代码不整洁，会使您面临意外的性能问题和篡改。@StevePy这不是您看到的我的控制器方法。这是存储库方法。我不是返回普通实体，而是返回一个DTO，在这里我为控制器选择必要的数据以返回。因此，感谢您的注意，但问题并不完全在于此。
var productsToReturn=productsFromRepo.Select（i=>i.Product）SelectproductsFromRepo.Select（I=>newproductdto{ProductId=I.Product.ProductId，/*etc*/Images=I.Images.Select（x=>newimagedto{/*将所需图像属性转换为DTO*/}）.ToList（）}var productsToReturn=productsFromRepo.Select（i=>i.Product）SelectproductsFromRepo.Select（I=>newproductdto{ProductId=I.Product.ProductId，/*etc*/Images=I.Images.Select（x=>newimagedto{/*将所需图像属性转换为DTO*/}）.ToList（）}