Need to Create a DCR with a random value

Hi ALL,

The requirement is that we need to create a field in a container of a DCR whose value will be a random integer value and will be initialised for the first time when we are creating a new form entry of a DCR.

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Comments

Migrateduser

What is the challenge that you are facing here? A random integer can be generated using javascript. you can set the value only if the name of the DCR is not set. is there anything else that is needed here?

Adam Stoller

Are you sure it needs to be just "random" - or does it need to be "random" and "unique" - or perhaps just "unique"?

I assume this is for some form of "id" - in which case I would think the emphasis would be on "unique" rather than "random".

Using the number of seconds since epoch usually works (e.g. in Perl:

my $id = time();

). Querying a DB for a sequence number would get you non-random unique values (and avoid the problem that two DCRs are created at the exact same second by [presumably] two different users)

Rick Poulin

My go-to for this type of thing is to generate a GUID in Javascript. If you must have a numeric value, you can hex2dec this value, but you'll need a LONG or a DOUBLE if you're storing it in a DB, in which case a VARCHAR(32) would be just as good.


function createGUID() {
    // http://www.ietf.org/rfc/rfc4122.txt
    var s = [];
    var hexChars = "0123456789ABCDEF";
    for (var i = 0; i < 32; i++) {
        s = hexChars.substr(Math.floor(Math.random() * hexChars.length), 1);
    }
    s[12] = "4";  // bits 12-15 of the time_hi_and_version field to 0010
    s[16] = hexChars.substr((s[16] & 0x3) | 0x8, 1);  // bits 6-7 of the clock_seq_hi_and_reserved to 01
    return s.join("");
}