Vee-validate (VueJS) - evaluating a condition asynchronously - vue.js

Question

Can I make a custom validation rule that returns true/false based on a AJAX request? the problem is that the validate call has finished running when the AJAX call completes.
Do I need to have the rule set/unset a boolean variable based on which the field is valid/invalid?
const isValidNameRule = {
getMessage(field)
{
return "The name must be unique."
},
validate(validatingName)
{
var formData = new FormData();
formData.append("validatingName", validatingName);
this.$http.post("/api/isValid?name=" + validatingName, formData)
.then(function (response) {
// success
return true;
}, function (response) {
// error
return false;
});
}
};

Answer 1

Didn't know how to work with Promises.
Eventually got it working by extending one of the official samples:
const customRule = {
getMessage(field, params, data) {
return (data && data.message) || 'Something went wrong';
},
validate(aValue) {
return new Promise(resolve => {
var formData = new FormData();
formData.append("nameFilter", aValue);
$.ajax({
type: "POST",
url: url,
data: {
action: "validate",
value: aValue,
}
}).done(function (data) {
if (!ok)
{
resolve({
valid: false,
data: {message: "Condition not met"}
});
}
else
{
resolve({
valid: !! aValue,
data: undefined
});
}
});
});
}
};