如何在 F# 中使用 EF Include 方法（加载相关数据）？

Question

如何使用 Include 方法在 F# 中预先加载相关数据我试过这个： _ctx.Reports.Include(x => x.Category) 并收到以下错误：

Severity Code Description Project File Line Suppression State Error FS0041 A unique overload for method 'Include' could not be determined based on type information prior to this program point. A type annotation may be needed.

Known type of argument: ^_arg3

Candidates: - (extension) Linq.IQueryable.Include<'TEntity when 'TEntity : not struct>(navigationPropertyPath: string) : Linq.IQueryable<'TEntity> - (extension) Linq.IQueryable.Include<'TEntity,'TProperty when 'TEntity : not struct>(navigationPropertyPath: Linq.Expressions.Expression>) : Query.IIncludableQueryable<'TEntity,'TProperty> SharpNews.Application E:[=11=]DevelopingLearn\BackEnd\ASP.NET Core\SharpNews\SharpNews.Application\Admin\Report\GetReports.fs 44 Active

还有两个错误是 x 未定义

我使用的语法不正确吗？

Answer 1

转换为 seq 或 IEnumerable<_> 就可以了

context.Users
    .Include(fun u -> u.Roles :> seq<Role>)

open System.Collections.Generic

context.Users
    .Include(fun u -> u.Roles :> IEnumerable<Role>)
        .ThenInclude(fun r -> r.Permissions)

如何在 F# 中使用 EF Include 方法（加载相关数据）？

How to use EF Include method(to load related data) in F#?

f#

entity-framework

eager-loading

c#-to-f#