Sharepoint - Custom error messages - sharepoint

Question

I'm a beginner sharepoint developer for a work project.
Specifications ask for custom error message.
When I create a list with a number field the error message is "Only numbers can go here".
<Field Name="Libelle" ID="{487dfca6-af3c-4939-94b1-2e5ae5aefb44}" DisplayName="Libelle" Type="Number" EnforceUniqueValues="TRUE" Indexed="TRUE" Required="TRUE" />
Can I change this?

Answer 1

The validation message for the SPField is a property on the field called ValidationMessage in the Microsoft.SharePoint namespace, or validationMessage in the SP namespace if you are working with the SP.js framework.
The validation message is controlled from a property that differs depending on what model you are using when developing towards SharePoint.
Field.ValidationMessage in the Microsoft.SharePoint.Client namespace
SP.Field.validationMessage in the SP.js namespace
SPField.ValidationMessage in the Microsoft.SharePoint namespace
Using C# to set the validation message on SPField
using (SPWeb web = site.OpenWeb())
{
//Get the list with your field
SPList list = web.Lists["Your list name here"];
//Get the field
SPField field = list["FieldName"];
field.ValidationMessage = "Your custom validation message.";
}
Using JSOM to set the validation message on SP.Field
function setValidationMessage() {
var context = SP.ClientContext.get_current();
var web = context.get_web();
var list = web.get_lists().getByTitle("Your list title");
var field = list.get_fields().getByInternalNameOrTitle("Your field title or internal name");
field.set_validationMessage("Your new validation message");
field.update();
context.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this.onQueryFailed));
}
function onQuerySucceeded() {
console.log("Validation message successfully updated!");
}
function onQueryFailed(sender, args) {
console.log("Failed to update validation message!");
}
Using the Sharepoint REST api to set the validation message on SP.Field
$.ajax({
url: _spPageContextInfo.siteAbsoluteUrl + "/_api/web/lists(listid)/fields(fieldid)/validationMessage",
type: "POST",
data: JSON.stringify({
'__metadata': {
'type': 'SP.Field'
},
'validationMessage': 'Your custom validation message!'
}),
headers: {
"IF-MATCH": "*",
"X-HTTP-Method":"PATCH",
"accept": "application/json;odata=verbose",
"content-type": "application/json;odata=verbose",
"X-RequestDigest": $("#__REQUESTDIGEST").val()
}
});
Additional info here.
You can also set the validation message from the settings in the SharePoint site by going to the column in site settings, select "Validation" and the "Validation message".

Answer 2

Open your list like this:-
https://site.sharepoint.com/Lists/List Title/NewForm.aspx?RootFolder=
Note:- Replace 'List Title' with your List Title
Edit this page and add 'Content Editor WebPart'(under 'Media and Content')
In content Editor Webpart Paste this script:-
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script type="text/javascript">
function isNumber(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
$(document).ready(function(){
$("input[title='Libelle']").blur(function(){
var txt = $("input[title='Libelle']").val();
if(!isNumber(txt)){
$("input[title='Libelle']").val("");
alert('Only numbers can go here');
}
});
});
</script>