Data-val-* attribute
A data-val-* attribute is an HTML data attribute convention for encoding validation metadata used by unobtrusive client-side validation.
Pro ASP.NET Core 7, Tenth Edition
A data-val attribute is an HTML data attribute emitted by ASP.NET Core to provide client-side validation metadata.
- How it is used
- Supplies HTML metadata that unobtrusive JavaScript uses to validate form fields before submission.
- How deep it goes
- Shows generated attributes and the scripts that consume them, but does not detail the JavaScript validator’s internals.
- Examples
- Uses generated ProductId and Name inputs, validation script listings, and an F12 check for absent HTTP requests.
- What you can do after
- Apply it via jQuery Validation and jQuery Validation Unobtrusive to display form errors without submitting invalid data.
Read how Pro ASP.NET Core 7, Tenth Edition explains data-val-* attribute →
ASP.NET Core in Action, 3e
A data-val-* attribute is an HTML attribute convention that encodes validation metadata for unobtrusive client-side validation libraries.
- How it is used
- Supports unobtrusive client-side validation by carrying DataAnnotations constraints from generated form fields to JavaScript libraries.
- How deep it goes
- Explains generated validation attributes and required scripts, but does not descend into library internals or custom rule implementation.
- Examples
- Shows an email input with data-val-email and data-val-required metadata, plus script references for unobtrusive validation.
- What you can do after
- Apply it via generated form markup and validation libraries to provide immediate feedback for invalid field values.
Read how ASP.NET Core in Action, 3e explains data-val-* attribute →
Related concepts
- dataannotations attributeproduced by · A DataAnnotations attribute is a .NET attribute that declares metadata or validation rules for types, members, and data-model elements.
- validationuses · The process of checking data, behavior, systems, models, or results against defined criteria to assess their correctness, suitability, or acceptability.
- unobtrusive validationused by · Unobtrusive validation is a client-side validation approach that represents rules in HTML data attributes and processes them through separate scripts.
- attributekind of · A programming-language attribute is declarative metadata associated with a program element that provides information or directives to compilers, tools, frameworks, or runtimes.
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