Find elements in CakePHP form field naming convention

gistfile1.js

// This is the naming convention for date fields
var field_name = "data[model][0][dob][day]";

// Existing regular expression for finding elements.
var reg_fields = /^data\[([a-zA-Z]+)\]\[(\d+)\]\[([a-zA-Z]+)\]\[([a-zA-Z]+)\]?$/ ;
 
// Match on date fields works ok (not sure why the first index is the full string).
field_elements = field_name.match(reg_fields); 
// returns [ "data[model][0][dob][day]" , "model" ,"0", "dob", "day" ]
 
// This is the naming convention for text fields
field_name = "data[model][0][first_name]";
 
// Match on text fields doesn't work.
field_elements = field_name.match(reg_fields); 
// returns null

Your regex isn’t quite saying what you think. It’s saying data[:letters:][:numbers:][:letters][:letters: or data[:letters:][:numbers:][:letters][:letters:] are the only valid matches†. You should change \[([a-zA-Z]+)\]?$ to (\[([a-zA-Z]+)\])?$/, if that’s not what you want.

† obviously using :letters: and :numbers: as proxies for ([a-zA-Z]+) and (\d+), respectively.

To answer your confusion (on line 7): when doing a match, it returns the entire portion in the string that matches the regex as the first item in the array.

Perhaps this would be a better approach:

var tmp = field_name.replace(/^data\[(.*)\]$/, '$1'); // "model][0][first_name"
field_elements = tmp.split(']['); // ["model", "0", "first_name"]

Hope that helps.

@SteveMarshall, those extra brackets around the final rule work a charm.

@remybach, that's not such a bad idea. That way, I've got a "clean" array of just the elements I'm after rather than the extra matches (now including the [day], [month] and [year] matches before day, month and year matches respectively).