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# F# Data: Anonymizing JSON
This tutorial shows how to implement an anonymizer for a JSON document (represented using
the `JsonValue` type discussed in [JSON parser article](JsonValue.html))
This functionality is not directly available in the F# Data library, but it can
be very easily implemented by recursively walking over the JSON document.
If you want to use the JSON anonymizer in your code, you can copy the
[source from GitHub][jsonanonymizer] and just include it in your project. If you use these
functions often and would like to see them in the F# Data library, please submit
a [feature request][issues].
*DISCLAIMER*: Don't use this for sensitive data as it's just a sample
#r "../../../bin/lib/net45/FSharp.Data.dll"
open System
open System.Globalization
open FSharp.Data
type JsonAnonymizer(?propertiesToSkip, ?valuesToSkip) =
let propertiesToSkip = Set.ofList (defaultArg propertiesToSkip [])
let valuesToSkip = Set.ofList (defaultArg valuesToSkip [])
let rng = Random()
let digits = [| '0' .. '9' |]
let lowerLetters = [| 'a' .. 'z' |]
let upperLetters = [| 'A' .. 'Z' |]
let getRandomChar (c:char) =
if Char.IsDigit c then digits.[rng.Next(10)]
elif Char.IsLetter c then
if Char.IsLower c
then lowerLetters.[rng.Next(26)]
else upperLetters.[rng.Next(26)]
else c
let randomize (str:string) =
String(str.ToCharArray() |> getRandomChar)
let rec anonymize json =
match json with
| JsonValue.String s when valuesToSkip.Contains s -> json
| JsonValue.String s ->
let typ =
CultureInfo.InvariantCulture s
( if typ = typeof<Guid> then Guid.NewGuid().ToString()
elif typ = typeof<Runtime.StructuralTypes.Bit0> ||
typ = typeof<Runtime.StructuralTypes.Bit1> then s
elif typ = typeof<DateTime> then s
let prefix, s =
if s.StartsWith "http://" then
"http://", s.Substring("http://".Length)
elif s.StartsWith "https://" then
"https://", s.Substring("https://".Length)
else "", s
prefix + randomize s )
|> JsonValue.String
| JsonValue.Number d ->
let typ =
CultureInfo.InvariantCulture (d.ToString())
if typ = typeof<Runtime.StructuralTypes.Bit0> ||
typ = typeof<Runtime.StructuralTypes.Bit1> then json
else d.ToString() |> randomize |> Decimal.Parse |> JsonValue.Number
| JsonValue.Float f ->
|> randomize
|> Double.Parse
|> JsonValue.Float
| JsonValue.Boolean _ | JsonValue.Null -> json
| JsonValue.Record props ->
|> (fun (key, value) -> key,
if propertiesToSkip.Contains key then value
else anonymize value)
|> JsonValue.Record
| JsonValue.Array array ->
|> anonymize
|> JsonValue.Array
member __.Anonymize json = anonymize json
let json = JsonValue.Load (__SOURCE_DIRECTORY__ + "../../data/TwitterStream.json")
printfn "%O" json
let anonymizedJson = (JsonAnonymizer ["lang"]).Anonymize json
printfn "%O" anonymizedJson
## Related articles
* [F# Data: JSON Parser](../library/JsonValue.html) - a tutorial that introduces
`JsonValue` for working with JSON values dynamically.
* [F# Data: JSON Type Provider](../library/JsonProvider.html) - discusses F# type provider
that provides type-safe access to JSON data.