如何在F＃中将任何记录转换为地图/词典？

Question

I need to serialize arbitrary records into maps/dictionary.

I imagine my end type look like this:

type TabularData= array<Map<string, obj>>

But I have problems in build a generic function that accept any record and turn them into Map.

Answer 1

In practice, the best advice is probably to use some existing serialization library like FsPickler . However, if you really want to write your own serialization for records, then GetRecordFields (as mentioned in the comments) is the way to go.

The following takes a record and creates a map from string field names to obj values of the fields. Note that it does not handle nested records and it is not particularly fast:

open Microsoft.FSharp.Reflection

let asMap (recd:'T) = 
  [ for p in FSharpType.GetRecordFields(typeof<'T>) ->
      p.Name, p.GetValue(recd) ]
  |> Map.ofSeq

Here is a little example that calls this with a simple record:

type Person =
  { Name : string 
    Age : int }

asMap { Name = "Tomas"; Age = -1 }

Answer 2

Using the same idea mentioned by Tomas, you can create a IDictionary<K,V> from a record like this:

let asDictionary (entity: 'T) =
    seq {
        for prop in FSharpType.GetRecordFields(typeof<'T>) -> 
        prop.Name, prop.GetValue(entity)
    } |> dict