Validate if the input value is within the range

In this example, the boundary values (2 and 99) are enterable.

RangeValidation.cshtml.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace WorkStandard.Pages.validation
{
    public class RangeValidationModel : PageModel
    {
        [BindProperty]
        [DisplayName("Count")]
        [Range(2, 99, ErrorMessage = "The {0} must be within the range {1} to {2}")]
        public int? Count { get; set; }

        public void OnPost()
        {
            if (!ModelState.IsValid)
            {
                return;
            }

            System.Diagnostics.Debug.WriteLine($"No errors {Count}");
        }
    }
}

→ Where Debug.WriteLine outputs to

RangeValidation.cshtml

@page
@model WorkStandard.Pages.validation.RangeValidationModel

<form method="post">
    <div class="mb-3">
        <label asp-for="Count"></label>
        <input asp-for="Count" class="form-control" />
        <span asp-validation-for="Count" class="text-danger"></span>
    </div>
    <div>
        <input type="submit" class="btn btn-primary" />
    </div>
</form>

The CSS classes...

• mb-3 Set little margin at bottom.→ Spacing
• form-control Make the input a Bootstrap look.→ Forms
• text-danger The string become red to indicate danger.→ Theme colors
• btn btn-primary Give the button a Bootstrap look to indicate that it's a key feature.→ Buttons

This example works with .NET 8 (2023) and later.

In this example, you can input 2 and 59.9, but 60 will be rejected.

RangeExclusiveValidation.cshtml.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace WorkStandard.Pages.validation
{
    public class RangeExclusiveValidationModel : PageModel
    {
        [BindProperty]
        [DisplayName("Weight")]
        [Range(2D, 60D, MaximumIsExclusive = true, ErrorMessage = "The {0} must be greater than or equal to {1} and less than {2}")]
        public double? Weight { get; set; }

        public void OnPost()
        {
            if (!ModelState.IsValid)
            {
                return;
            }

            System.Diagnostics.Debug.WriteLine($"No errors {Weight}");
        }
    }
}

→ Where Debug.WriteLine outputs to

Note: If you need exclusive minimum value, you must set MinimumIsExclusive = true.

RangeExclusiveValidation.cshtml

@page
@model WorkStandard.Pages.validation.RangeExclusiveValidationModel

<form method="post">
    <div class="mb-3">
        <label asp-for="Weight"></label>
        <input asp-for="Weight" class="form-control" />
        <span asp-validation-for="Weight" class="text-danger"></span>
    </div>
    <div>
        <input type="submit" class="btn btn-primary" />
    </div>
</form>

The CSS classes...

• mb-3 Set little margin at bottom.→ Spacing
• form-control Make the input a Bootstrap look.→ Forms
• text-danger The string become red to indicate danger.→ Theme colors
• btn btn-primary Give the button a Bootstrap look to indicate that it's a key feature.→ Buttons

RangeDateValidation.cshtml.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace WorkStandard.Pages.validation
{
    public class RangeDateValidationModel : PageModel
    {
        [BindProperty]
        [DisplayName("Date of birth")]
        [DataType(DataType.Date)]
        [Range(typeof(DateTime), "1900/1/1", "2099/12/31", ErrorMessage = "The {0} must be within the range {1:MM/dd/yyyy} to {2:MM/dd/yyyy}")]
        public DateTime? BirthDate { get; set; } = DateTime.Now;

        public void OnPost()
        {
            if (!ModelState.IsValid)
            {
                return;
            }

            System.Diagnostics.Debug.WriteLine($"No errors {BirthDate}");
        }
    }
}

→ Where Debug.WriteLine outputs to

RangeDateValidation.cshtml

@page
@model WorkStandard.Pages.validation.RangeDateValidationModel

<form method="post">
    <div class="mb-3">
        <label asp-for="BirthDate"></label>
        <input asp-for="BirthDate" class="form-control" />
        <span asp-validation-for="BirthDate" class="text-danger"></span>
    </div>
    <div>
        <input type="submit" class="btn btn-primary" />
    </div>
</form>

The CSS classes...

• mb-3 Set little margin at bottom.→ Spacing
• form-control Make the input a Bootstrap look.→ Forms
• text-danger The string become red to indicate danger.→ Theme colors
• btn btn-primary Give the button a Bootstrap look to indicate that it's a key feature.→ Buttons