Question : How to parse a JSON string about fleece HOT 4 CLOSED

Hi! No question is dumb.

parseJSON does take a string as parameter, but it returns a Choice<'a, string>.
If it's Choice1Of2 then the parsing was successful and you have the parsed value.
If it's Choice2Of2 then there was some parsing error and you get the error message as a string, which you can use to throw as an exception, display to the user or whatever you like.

Does that make sense?

To create a "singleton" instance of Config I recommend using F#'s lazy expressions

Cheers

from fleece.

Thanks for the answer and the tips.

I think I understand an then if the result is successful then I can pass it to FromJson of ConfigJson ?

from fleece.

No, FromJson is called implicitly by parseJSON, you don't need to call it
in your code.
On 31 May 2016 13:35, "Maxime Mangel" [email protected] wrote:

Thanks for the answer and the tips.

I think I understand an then if the result is successful then I can pass
it to FromJson of ConfigJson ?

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from fleece.

Ok :) Thanks for the help.

I am letting here my problem solved.

namespace Server

open System
open Fleece
open Fleece.Operators
open FSharpPlus

type ConfigJson = {
    RelativeRoot: string
    Server: string
    Database: string
    Uid: string
    Pwd: string
}

type ConfigJson with 
    static member Create relativeRoot server database uid pwd= 
        { 
            ConfigJson.RelativeRoot = relativeRoot;
            ConfigJson.Server = server;
            ConfigJson.Database = database;
            ConfigJson.Uid = uid;
            ConfigJson.Pwd = pwd;
        }

    static member FromJSON (_:ConfigJson) = 
        function
        | JObject o -> ConfigJson.Create <!> (o .@ "relativeRoot") <*> (o .@ "server") <*> (o .@ "database") <*> (o .@ "uid") <*> (o .@ "pwd")
        | x -> Failure (sprintf "Expected ConfigJson, found %A" x)

module Config =

    let config: ConfigJson =
        let data: ConfigJson ParseResult = parseJSON(System.IO.File.ReadAllText("server.json"))

        match data with
        | Success a -> a
        | Failure e -> failwith "Error when parsing json file"

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