Created
August 23, 2019 14:16
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Convert string list option to an empty list in Json
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open System | |
open Microsoft.FSharp.Reflection | |
open Newtonsoft.Json | |
open Newtonsoft.Json.Converters | |
type OptionConverter() = | |
inherit JsonConverter() | |
override x.CanConvert(t) = | |
t.IsGenericType && t.GetGenericTypeDefinition() = typedefof<option<_>> | |
override x.WriteJson(writer, value, serializer) = | |
let value = | |
if isNull value then null | |
else | |
let _,fields = FSharpValue.GetUnionFields(value, value.GetType()) | |
fields.[0] | |
serializer.Serialize(writer, value) | |
override x.ReadJson(reader, t, existingValue, serializer) = | |
let innerType = t.GetGenericArguments().[0] | |
let innerType = | |
if innerType.IsValueType then (typedefof<Nullable<_>>).MakeGenericType([|innerType|]) | |
else innerType | |
let value = serializer.Deserialize(reader, innerType) | |
let cases = FSharpType.GetUnionCases(t) | |
if isNull value then FSharpValue.MakeUnion(cases.[0], [||]) | |
else FSharpValue.MakeUnion(cases.[1], [|value|]) |
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