Unable to parse string to datastore.Key

Question

With reference to this question, I am trying to convert a datastore key from the Form to int64 and with the help of that key, trying to update a record in the datastore. I tried exactly the same code as in the answer selected in the reference link, but I get an error which says, Unable to parse key. strconv.ParseInt: parsing "/Users,6248007768440574": invalid syntax

The value I'm passing from the form is a datastore key of the format /Users,6248007768440574. I realize that the syntax error is because of this. Could anyone please help me in how to go about with this issue? Or, is there a method to convert a string to *datastore.Key? Any help will be appreciated

Answer 1

ParseInt returns an error because the string "/Users,6248007768440574" is not an integer. A substring is an integer, but not the entire string.

The string in the question was created by calling Key.String. The datastore package does not provide a way to parse the output from this method. Here's a simple parser for the case where there are no ancestor keys:

var keyPat = regexp.MustCompile(`^/([^\.]*),(\d+)$`)

func parseKey(s string) (*datastore.Key, error) {
    m := keyPat.FindStringSubmatch(s)
    i := strings.Index(s, ",")
    if i < 0 {
        return nil, errors.New("bad format")
    }
    n, err := strconv.ParseInt(m[2], 10, 64)
    if err != nil {
        return nil, err
    }
    return datastore.IDKey(m[1], n, nil), nil
}

The the Encode method and Decode function are the preferred way to convert a key to and from a machine readable string.