Edit Field Validation - Use of the native string.find() Lua Function

Question

Hi,
I have an edit field in which I want to be validated immediately upon change.  I ONLY want to accept alphanumeric characters (a-z and 0-9).  I have tried this many ways, but have failed to get it exactly as I want it.  First I tried Sample Code A, but that line of code fails because combination strings that contain the alphanumeric characters and a special character like the pound sign (#), will validate (Example: "hello1#").  I tried Sample Code B, but that isn't 100% what I want because if you were to add a character that isn't available on the keyboard, such as the copyright symbol or the trademak symbol.  Can someone help me, please?  Thank you.
Sample Code A:
interface:edit_field {
                            value = bind { key = 'new_table', object = properties },
                            fill_horizontal = 1,
                            immediate = true,
                            validate = function (interface, value)
                              if string.find(value, "[a-z%d]")  then
                                return true, value, "good"
                            else
                                    return false, value, "failed"
                                end
                            end
Sample Code B:
interface:edit_field {
                            value = bind { key = 'new_table', object = properties },
                            fill_horizontal = 1,
                            immediate = true,
                            validate = function (interface, value)
                                if string.find(value, "[~!@#$%^&*()_+`-={}|\%[%]:\";'<>?,./]")  then
                                return false, value, "failed"
                            else
                                    return true, value, "good"
                                end
                            end

Answer 1

wallanceM wrote:
Hi,
I have an edit field in which I want to be validated immediately upon change.  I ONLY want to accept alphanumeric characters (a-z and 0-9).
Sample Code A:
interface:edit_field {
                            value = bind { key = 'new_table', object = properties },
                            fill_horizontal = 1,
                            immediate = true,
                            validate = function (interface, value)
                              if string.find(value, "[a-z%d]")  then
                                return true, value, "good"
Hi,
Sample Code A seems the best approach to use.  Trying to detect unwanted characters would be error prone.
I noticed you are mixing character classes and ranges in your string.find pattern.  Have you tried using the following patterns instead?
                              if string.find(value, "[a-z0-9]")  then
or
                              if string.find(value, "[%l%d]")  then
Matt