CompnayName column value must begin with "CompnayName :" value come

Question

any one tell that how to validate in Model in web api core using data annotation?

Sandhiya Priya · Answer

1. Add Data Annotation Attributes in Your Model ASP.NET Core automatically validates these before entering your controller action. Example Model public class RegisterRequest { [Required(ErrorMessage = "Username is required")] [StringLength(20, MinimumLength = 3)] public string Username { get; set; } [Required] [EmailAddress(ErrorMessage = "Invalid Email format")] public string Email { get; set; } [Required] [MinLength(6, ErrorMessage = "Password must be at least 6 characters")] public string Password { get; set; } [Range(18, 60, ErrorMessage = "Age must be between 18 and 60")] public int Age { get; set; } } 2. Validate in Controller Using ModelState ASP.NET Core automatically populates ModelState . [HttpPost("register")] public IActionResult Register([FromBody] RegisterRequest model) { if (!ModelState.IsValid) { return BadRequest(ModelState); // returns all validation errors } return Ok("Registration successful"); } 3. Enable Automatic Validation (Built-in in ASP.NET Core 3+) From .NET Core 3 and above, automatic model validation is enabled by default . Meaning: 1. You don't need to manually check ModelState.IsValid 2. The framework returns 400 BadRequest with validation errors automatically. But if you prefer manual checking (recommended for custom responses), use the previous method. 4. Optional: Customize Validation Response If you want cleaner error messages: if (!ModelState.IsValid) { var errors = ModelState.Values .SelectMany(v => v.Errors) .Select(e => e.ErrorMessage) .ToList(); return BadRequest(new { Success = false, Errors = errors }); } Bonus: Custom Validation Attribute Example public class NoSpaceAttribute : ValidationAttribute { public override bool IsValid(object value) { if (value == null) return true; return !value.ToString().Contains(" "); } } Use it like: [NoSpace(ErrorMessage = "Username cannot contain spaces")] public string Username { get; set; } Summary Step What you do 1 Add validation attributes in your model 2 Check ModelState.IsValid in controller 3 OR let ASP.NET automatically return 400 4 Customize validation response (optional)

CompnayName column value must begin with "CompnayName :" value come

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