Prototype - Template class and JSON

[addywaddy]

Hi,

I'm wanting to use a Template for an active record object that has
been converted to json.

The resulting json is along these lines:

var group_with_admin = {"attributes" : {"name" : "Group 1"}, "users" :
{"attributes" : { "first" : "John"}}};

var groupTemplate = new Template('#{attributes.name} is administered
by #{users.attributes.first}');

groupTemplate.evaluate(group_with_admin); // -> is administered by

and if i change the template to ('#{attributes} is administered by
#{users}');

groupTemplate.evaluate(group_with_admin); // -> [object Object] is
administered by [object Object]

Obviously what I'm hoping for is to be able to render Group1 is
administered by John. Is there a way of doing this using the Template
class?

Regards

Adam

[Christophe Porteneuve]

Hi Adam,

addywaddy a écrit :

> var groupTemplate = new Template('#{attributes.name} is administered
> by #{users.attributes.first}');

Currently Template only uses direct properties of the evaluated object:
it doesn't go down. That's rather simple to fix, though. I'll consider
a patch soon about this, in the meantime here's a working fix:

evaluate: function(object) {
return this.template.gsub(this.pattern, function(match) {
var before = match[1];
if (before == '\\') return match[2];
// START OF FIX
var obj = object;
match[3].split('.').each(function(comp) {
if (obj)
obj = obj[comp];
});
return before + String.interpret(obj);
// END OF FIX
});
}

--
Christophe Porteneuve aka TDD
t...@tddsworld.com

[addywaddy]

A reply from the mighty Christophe!

Thanks for this mate. That'll make it child's play for updating the
page with an array of active record objects.

All the best

Adam

[addywaddy]

Christophe,

I mistyped my JSON:

var group_with_admin = {"attributes" : {"name" : "Group 1"}, "users" :

[{"attributes" : { "first" : "John"}}]};

users is an array. So I tried this:

var groupTemplate = new Template('#{attributes.name} is administered

by #{users[0].attributes.first}');

Thanks to your fix, #{attributes.name} renders "Group 1", but I can't
get to "John". My active record object is the result of this finder:

Group.find(:first, :include => :users)

where groups have many users.

I presume this isn't such a straight-forward fix. Any pointers? This
is the first time I've actually looked at the source code for
prototype - shame on me!

Regards

Adam

[Christophe Porteneuve]

Hey Andy,

addywaddy a écrit :

> Thanks to your fix, #{attributes.name} renders "Group 1", but I can't
> get to "John". My active record object is the result of this finder:

Yeah. I guess the fix can be made even more trivial by relying on the
String#evalJSON method in sanitized mode instead of manually running the
string.

Basically, this just requires prefixing each dynamic fragment with
"object." or something, then evalJSON'ing.

I don't have a minute to spare just now but you should try along these
lines, it probably goes something like this:

// START OF FIX
return before + ('object.' + match[3]).evalJSON(true);
// END OF FIX