是否可以混合使用 LINQ 和动态字符串查询来编写 EF Core 查询？

Question

我希望能够在 LINQ 中编写大部分查询，但随后将 WHERE 子句写为字符串，就像动态查询一样。所以像：

var query = from part in _context.CurrentInventory

query.Where = "part.PartNumber LIKE '%a%' OR part.PartNumber LIKE '%b%'

原因是因为 WHERE 会变得非常大，使用 EF.Functions.Like 和 Contains 确实会减慢查询速度。

我可以动态构建整个东西并只执行字符串，但我希望避免这种情况。

Answer 1

你可以使用System.Linq.Dynamic which is based on以前的作品

    Install-Package System.Linq.Dynamic

查询

   query.Where = "part.PartNumber LIKE '%a%' OR part.PartNumber LIKE '%b%'

可以re-written为：

    query.Where ("part.PartNumber.Contains(@0) or part.PartNumber.Contains(@1)","a" ,"b")

fiddle

的工作示例

更新：

我将动态 Linq 与 EntityFramework

结合使用

      using (var context = new NorthwindEntities())
        {
            var customers = context.Customers.Where("ContactName.Contains(@0) or ContactName.Contains(@1)", "Maria","Carine").ToList();
            Console.WriteLine(customers.Count);
        }

生成的 Sql（从 sql 分析器中看到）是：

    SELECT 
        [Extent1].[CustomerID] AS [CustomerID], 
        [Extent1].[CompanyName] AS [CompanyName], 
        [Extent1].[ContactName] AS [ContactName], 
        [Extent1].[ContactTitle] AS [ContactTitle], 
        [Extent1].[Address] AS [Address], 
        [Extent1].[City] AS [City], 
        [Extent1].[Region] AS [Region], 
        [Extent1].[PostalCode] AS [PostalCode], 
        [Extent1].[Country] AS [Country], 
        [Extent1].[Phone] AS [Phone], 
        [Extent1].[Fax] AS [Fax]
        FROM [dbo].[Customers] AS [Extent1]
     WHERE ([Extent1].[ContactName] LIKE N'%Maria%') OR ([Extent1].[ContactName] LIKE N'%Carine%')

where条件翻译为：

     WHERE ([Extent1].[ContactName] LIKE N'%Maria%') OR ([Extent1].[ContactName] LIKE N'%Carine%')

是否可以混合使用 LINQ 和动态字符串查询来编写 EF Core 查询？

Is it possible to mix writing an EF Core query with LINQ and a dynamic string query?

c#

entity-framework-core

ef-core-2.0