Generate JSON from Nustache with proper escaping - json

Question

I would like to use Nustache to generate JSON to talk to a specific webservice.
I do not want to do proper JSON-building using Newtonsoft or something like that because the specs for this webservice come as textfiles with placeholders. I agree that this is silly. So it makes sense to copy/massage/paste them into a template-format and hopefully make fewer mistakes.
But of course Nustache has no notion of what makes valid JSON.
With a template like
{ "foo": "{{bar}}" }
and a value for bar that needs escaping in JSON, say it includes curly brackets or an innocent backslash the result is string-replacy-correct, but not valid JSON.
Is there a way to tell Nustache that I want the output to be JSON and have it escape strings as it replaces them?
Or would you recommend doing a helper that can manage the escaping and put that on all the placeholders?
Thanks for reading and thinking.

Answer 1

I did not find a wholly satisfactory answer but a workable solution.
My workaround is a Nustache helper that takes care of the quoting and escaping. The ugly bit is that I need to specify the helper in the template in each instance:
{ "foo": "{{json bar}}" }
The helper implementation is trivial and can be listed fully here. For the actual work it delegates to JsonConvert from Newtonsoft JSON:
public class JSONHelpers
{
public static void Register()
{
if (!Helpers.Contains("json"))
{
Helpers.Register("json", JSON);
}
}
private static void JSON(RenderContext ctx, IList<object> args, IDictionary<string, object> options,
RenderBlock fn, RenderBlock inverse)
{
object input = args[0];
if (input == null)
{
ctx.Write("null");
}
else
{
string text = input.ToString();
string json = JsonConvert.ToString(text);
ctx.Write(json);
}
}
}
Hopefully this comes useful to someone else.