I like it a lot! I think it looks pretty cool left some minor comments

updated the PR based on your comments

a small amount of comments but LGTM !!

I'd love to see some examples of more complicated templates, including mustache sections, use of arrays etc.

Also, is the automatic html encoding of output turned off?

hrm...

{
    "template" : {
        "query": { "filtered" : {
            "query" : { "match_all" : {} },
            "filter" : { "owner" : "{{user}}" }
         },
        "aggs" : {
        {{#aggs}}
          "{{.}}" : { "terms" : { "field" : "{{.}}" }  }
        {{/aggs}}
        }
    },
    "params" : {
        "user" : "kimchy",
        "aggs" : [ "category_id", "sub_category_id" ]
    }
}

something like this will not produce valid JSON, as you cannot check for the last element of an array with mustache, thanks to logicless template... need to think about this in order to solve it nicely, makes mustache somewhat limited here for our needs...

i do wonder if mustache is the right answer here... You can certainly make it do the right thing, but I wonder how easy it will be for the user to write.

it's just a scripting engine so you can plug in whatever produces a string?

yeah, but i'm thinking more of the existing dsl with some added operators... not sure. need to play with it a bit

OK I've worked through various non-trivial examples of templating using mustache, and added a number of worked examples to the docs page: See spinscale#2

There are some things (conditional clauses) which can't be expressed using the JSON form of templates, but can be expressed as strings. I've included an example in the PR.

One thing that needs to be fixed is the escape method. Currently it escapes characters as expected for HTML, eg " -> ". This is clearly wrong. Instead, we should be using these escapes:

\b  Backspace (ascii code 08)
\f  Form feed (ascii code 0C)
\n  New line
\r  Carriage return
\t  Tab
\v  Vertical tab
\"  Double quote
\\  Backslash 

LGTM lets push this @spinscale

I've opened the escaping bug as a separate issue #5473