F#：使用 FluntNHibernate 时查找不确定类型的对象

发布于 2024-10-03 11:19:55 字数 465 浏览 4 评论 0原文

我尝试通过 FluentNHibernate 在 F# 项目中配置 NHibernate。

 static member GetNHibernateConfig = 
    Fluently.Configure()
            .Database(MsSqlConfiguration.MsSql2008
                .ConnectionString(fun c -> c.FromConnectionStringWithKey("connectionString") |> ignore)
                    .ShowSql())

Visual Studio 突出显示“c.FromConnectionStringWithKey”并显示错误：

根据此程序点之前的信息查找不确定类型的对象。在此程序点之前可能需要类型注释来约束对象的类型。这可以使查找得以解决。

原文

I try to configure NHibernate in F# project by FluentNHibernate.

 static member GetNHibernateConfig = 
    Fluently.Configure()
            .Database(MsSqlConfiguration.MsSql2008
                .ConnectionString(fun c -> c.FromConnectionStringWithKey("connectionString") |> ignore)
                    .ShowSql())

Visual Studio highlight "c.FromConnectionStringWithKey" with error:

Lookup on object of indeterminate type based on information prior to this program point. A type annotation may be needed prior to this program point to constrain the type of the object. This may allow the lookup to be resolved.

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冷清清 2024-10-10 11:19:55

我对此一无所知，但通过在网上搜索 API 文档，我会尝试
更改

fun c ->

为

fun (c:ConnectionStringBuilder) ->

因为这个

http://fluentnhibernate.org/api/FluentNHibernate .Cfg.Db/PersistenceConfiguration%602.htm#ConnectionString

向我表明这可能是 c 的类型。

编辑：（

显然类型是 MsSqlConnectionStringBuilder。）

无论如何，更一般地说，如果您遇到 F# 在 C# 时不推断 lambda 类型，那么

您可能正在使用具有多个重载的方法
的某些子集重载使用 Action 或 Func

，最简单的方法是显式添加 Action 或 Func 委托类型，以便 F#正确解决过载问题。对于这种情况，我觉得改一下

.ConnectionString(fun c -> ...)

就

.ConnectionString(Action<MsSqlConnectionStringBuilder>(fun c -> ...))

可以解决，这往往是最便捷的解封方式。

I don't know anything about this, but from searching the web for API docs, I would try
changing

fun c ->

fun (c:ConnectionStringBuilder) ->

because this

http://fluentnhibernate.org/api/FluentNHibernate.Cfg.Db/PersistenceConfiguration%602.htm#ConnectionString

suggests to me that that may be the type of c.

EDIT:

(Apparently the type is MsSqlConnectionStringBuilder.)

Anyway, more generally, if you run into F# not inferring lambda types when C# does, then probably

you're using a method with multiple overloads
some subset of the overloads use Action or Func

and the easiest thing is to explicitly add the Action or Func delegate type so that F# correctly resolves the overload. In this case, I think changing

.ConnectionString(fun c -> ...)

.ConnectionString(Action<MsSqlConnectionStringBuilder>(fun c -> ...))

fixes it, and this is often the most expedient way to get unblocked.

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朱染 2024-10-10 11:19:55

不知道为什么，但声明函数参数的类型是有效的：

Fluently.Configure()
        .Database(MsSqlConfiguration.MsSql2008
            .ConnectionString(fun (c: MsSqlConnectionStringBuilder) -> c.FromConnectionStringWithKey("connectionString") |> ignore)
                .ShowSql())

无论如何，你最好使用 FunctionalNHibernate< /a> 代替 F# 中的 FluentNHibernate。

Not sure why, but declaring the type of the function parameter works:

Fluently.Configure()
        .Database(MsSqlConfiguration.MsSql2008
            .ConnectionString(fun (c: MsSqlConnectionStringBuilder) -> c.FromConnectionStringWithKey("connectionString") |> ignore)
                .ShowSql())

Anyway, you'll be better off using FunctionalNHibernate instead of FluentNHibernate in F#.

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