应该如何将F#SqlDataConnection TypeProvider与App.Config文件一起使用? [英] How is one supposed to use the F# SqlDataConnection TypeProvider with an App.Config file?

问题描述

我正在使用类型表达式:

I am using the type expression:

type dbSchema = SqlDataConnection<ConnectionStringName="X1", ConfigFile="App.config">

这在编译时效果很好(我拥有对所有数据库类型的完全访问权限)，但在运行时失败.我猜这是因为在控制台应用程序的bin目录中生成的配置文件被命名为其他名称，例如MyAppName.exe.config，因此找不到App.config文件.

This works great at compile time (I have full access to all the db types), but it fails at run time. I presume it's because the config file generated in the console application's bin directory is named something else, such as MyAppName.exe.config, and therefore the App.config file is not found.

当然，对于使用web.config的 ASP.NET MVC 类型的应用程序，没有问题，因为编译和运行时配置文件名相同.

Certainly, for an ASP.NET MVC type app that uses web.config, there's no issue because the compile and runtime config filenames are the same.

幸运的是，在bin目录中放置重复的App.config确实可以解决问题，但这是我们所期望的吗?有什么想法吗?

Fortunately, placing a duplicate App.config in the bin directory does remediate the problem, but is that what we are expected to do? Any thoughts?

推荐答案

关于类型提供程序定义的工作方式的描述具有误导性-typedef中的值实际上仅在代码/编译时才有效，而在运行时则作为默认值.但是，您已经注意到，在运行时查找正确的配置文件不是很聪明.

The description of how the type provider definition works is misleading - the value in the typedef really only matters at code/compile time, and as a default at runtime. However, as you've noted, it isn't very smart about finding the correct config file at runtime.

您可以通过将连接字符串作为参数传递给GetDataContext来完成所需的操作:

You can accomplish what you want by passing the connection string as a parameter to GetDataContext:

type dbSchema = SqlDataConnection<ConnectionStringName="X2">
let db = dbSchema.GetDataContext(ConfigurationManager.ConnectionStrings.["X2"].ConnectionString)

...或者如果您也想使其在F#交互式环境中工作，请像这样包装它:

...or if you also want to make it work in F# interactive, wrap it like so:

type dbSchema = SqlDataConnection<ConnectionStringName="X2">
#if COMPILED
let db = dbSchema.GetDataContext(ConfigurationManager.ConnectionStrings.["X2"].ConnectionString)
#else
let db = dbSchema.GetDataContext()
#endif

(请注意，您将需要引用System.Configuration.)

(Note that you will need a reference to System.Configuration.)

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