Forum OpenACS Q&A: Re: validation

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5: Re: validation (response to 4)
Posted by Randy O'Meara on
Here's a method I use that utilizes a procedure to validate:

In your form processing page code:

} -validate {
    {value {[valid_value err $value]} $err }
}
"err" is a var parameter that is set by procedure validate_value. On error you set it with the appropriate error message.

And the procedure looks something like:

ad_proc -public valid_value {
    err
    value
} {
    Validates value.
    @return 1 if valid, $err == "".  0 if invalid, $err == descriptive string.
    @param err name of var parameter, in caller's scope, that receives error description.
    @param value the value to be validated.
} {
    upvar 1 $err lerr
    if {[string length $value] < 3} {
	set lerr "\"value\" must be a string containing three or more characters"
	return 0
    }
    set lerr ""
    return 1
}
This might seem like overkill for this simple example, but more complex checks and/or recovery can be performed in a more complex situation.

/R