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I have a Bootstrap 4 form with an input field, called runname. I want to perform the following validation on the input field:
runname cannot be emptyrunname cannot contain spacesrunnamecannot already be used previouslyI already have the code for a form which gives an error, using custom Bootstrap styles if the input field is empty:
// JavaScript for disabling form submissions if there are invalid fields
(function() {
'use strict';
window.addEventListener('load', function() {
// Fetch all the forms we want to apply custom Bootstrap validation styles to
var forms = document.getElementsByClassName('needs-validation');
// Loop over them and prevent submission
var validation = Array.prototype.filter.call(forms, function(form) {
form.addEventListener('submit', function(event) {
if (form.checkValidity() === false) {
event.preventDefault();
event.stopPropagation();
}
form.classList.add('was-validated');
}, false);
});
}, false);
})();<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" integrity="sha384-WskhaSGFgHYWDcbwN70/dfYBj47jz9qbsMId/iRN3ewGhXQFZCSftd1LZCfmhktB" crossorigin="anonymous">
</head>
<body class="bg-light">
<div class="container">
<div class="col-md-12 order-md1">
<form class="needs-validation" novalidate method="post" action="#">
<div class="form-group row">
<label for="inputRunname" class="col-sm-2 col-form-label">Run name</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="inputRunname" name="runname" placeholder="Run name" required>
<div class="invalid-feedback">
Please enter a run name
</div>
</div>
</div>
<div class="form-group row">
<div class="col-sm-10">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
</form>
</div>
</div>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js" integrity="sha384-smHYKdLADwkXOn1EmN1qk/HfnUcbVRZyYmZ4qpPea6sjB/pTJ0euyQp0Mk8ck+5T" crossorigin="anonymous"></script>
</body>
</html>And I have some Javascript to check if an input contains spaces:
function cannotContainWhiteSpace(input, errorId, name) {
var value = input.value;
var errMsgHolder = document.getElementById(errorId);
if (!(/^\S*$/.test(value))) {
errMsgHolder.innerHTML =
'The ' + name + ' cannot contain whitespace';
input.focus();
return false;
}
}And I also have some Python code on my Cherrypy backend which does a lookup in the database to see if the runname already exists:
try:
myConnection = mysql.connector.connect(host=self.database['host'], user=self.database['user'], passwd=self.database['passwd'], db=self.database['db'])
cursor = myConnection.cursor(buffered=True)
# unless overriden by the force flag, check whether the runname has already been used before
if not force:
reusedrunquery = "SELECT run FROM logs WHERE run = %s AND errormessage IS NULL"
cursor.execute(reusedrunquery, (runname,))
if cursor.fetchall():
flag = True
cherrypy.session['reusedRun'] = True
myConnection.close()
except mysql.connector.Error as err:
return self.database_failure(str(err))
But I don't know how to cobble all these different parts together to get a form where I have both the two client-side validations and the server-side validation.
508
On Submit event, you should have a method in your backend that actually intercepts the request and I think there you should be able to make a connection with your backend's logic.
Here they are the steps:
onSubmit eventOtherwise, you may try to make an AJAX call on which there will be executed the client-side validations and then it will call the server-side method/class for checking that runname has been used already.
138
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