As of jQuery Validate 1.11.1 (and perhaps even older), the accepted answer does not work. In addition, there is no easy answer to this question, and the solution requires adding a custom validation method to jQuery Validation.
Actually, the easy answer may just be: Don’t call valid() manually if all you want to do is submit the form. Just let the Validate plugin do it for you. Internally, it will wait for all asynchronous requests to complete before allowing the form to be submitted. This issue only arises when you are manually checking valid() or element().
However, there are plenty of reasons why you may need to do that. For instance, the page I am working on needs to check the validity of a field using a remote validator before enabling the rest of the form. I could just do it by hand instead of using jQuery Validation, but that’s a duplication of effort.
So, why does setting async: false not work? If you set async to false, the request will be made synchronously, however, the plugin doesn’t handle this correctly. The internal remote function always returns "pending" which will cause the valid() function to return true even if the request is already complete and received a false response! It doesn’t check the value of the response or show the error until later.
The solution to making valid() and element() behave synchronously when using a synchronous callback is to add a custom validation method. I’ve tried this myself, and it seems to work fine. You can just copy the source code from the regular remote validation and modify it to handle synchronous ajax calls, and be synchronous by default.
The source code of of the remote function in v1.11.1 starts on line 1112 of jquery.validate.js:
remote: function( value, element, param ) {
if ( this.optional(element) ) {
return "dependency-mismatch";
}
var previous = this.previousValue(element);
if (!this.settings.messages[element.name] ) {
this.settings.messages[element.name] = {};
}
previous.originalMessage = this.settings.messages[element.name].remote;
this.settings.messages[element.name].remote = previous.message;
param = typeof param === "string" && {url:param} || param;
if ( previous.old === value ) {
return previous.valid;
}
previous.old = value;
var validator = this;
this.startRequest(element);
var data = {};
data[element.name] = value;
$.ajax($.extend(true, {
url: param,
mode: "abort",
port: "validate" + element.name,
dataType: "json",
data: data,
success: function( response ) {
validator.settings.messages[element.name].remote = previous.originalMessage;
var valid = response === true || response === "true";
if ( valid ) {
var submitted = validator.formSubmitted;
validator.prepareElement(element);
validator.formSubmitted = submitted;
validator.successList.push(element);
delete validator.invalid[element.name];
validator.showErrors();
} else {
var errors = {};
var message = response || validator.defaultMessage( element, "remote" );
errors[element.name] = previous.message = $.isFunction(message) ? message(value) : message;
validator.invalid[element.name] = true;
validator.showErrors(errors);
}
previous.valid = valid;
validator.stopRequest(element, valid);
}
}, param));
return "pending";
}
Notice how it always returns “pending” even if the ajax call is complete.
To fix this issue, make the following modifications:
- Move the declaration of the
validvariable outside of the ajax call and the success function in order to make a closure, and assign it a default value of “pending”. - Change the old declaration of the
validvariable to an assignment. - Return the
validvariable instead of the constant “pending”.
Here’s the complete code for a plugin to the plugin. Just save this as a js file and include it in your page or template after the include for jQuery Validation:
//Created for jQuery Validation 1.11.1
$.validator.addMethod("synchronousRemote", function (value, element, param) {
if (this.optional(element)) {
return "dependency-mismatch";
}
var previous = this.previousValue(element);
if (!this.settings.messages[element.name]) {
this.settings.messages[element.name] = {};
}
previous.originalMessage = this.settings.messages[element.name].remote;
this.settings.messages[element.name].remote = previous.message;
param = typeof param === "string" && { url: param } || param;
if (previous.old === value) {
return previous.valid;
}
previous.old = value;
var validator = this;
this.startRequest(element);
var data = {};
data[element.name] = value;
var valid = "pending";
$.ajax($.extend(true, {
url: param,
async: false,
mode: "abort",
port: "validate" + element.name,
dataType: "json",
data: data,
success: function (response) {
validator.settings.messages[element.name].remote = previous.originalMessage;
valid = response === true || response === "true";
if (valid) {
var submitted = validator.formSubmitted;
validator.prepareElement(element);
validator.formSubmitted = submitted;
validator.successList.push(element);
delete validator.invalid[element.name];
validator.showErrors();
} else {
var errors = {};
var message = response || validator.defaultMessage(element, "remote");
errors[element.name] = previous.message = $.isFunction(message) ? message(value) : message;
validator.invalid[element.name] = true;
validator.showErrors(errors);
}
previous.valid = valid;
validator.stopRequest(element, valid);
}
}, param));
return valid;
}, "Please fix this field.");
I’ve tested this with my own form and it works great. I can test my element for validity before enabling the rest of the form. However, you probably want to set onkeyup: false to prevent performing a synchronous callback on every key press. I also like to use onfocusout: false.
To use this, just replace “remote” in your validation settings with “synchronousRemote” everywhere you’d like to use this. For example:
$("#someForm").validate({
rules: {
someField: {
required: true,
synchronousRemote: {
url: "/SomePath/ValidateSomeField"
//notice that async: false need not be specified. It's the default.
}
}
},
messages: {
someField: {
required: "SomeField is required.",
synchronousRemote: "SomeField does not exist."
}
},
onkeyup: false,
onfocusout: false
});