1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
using System.ComponentModel.DataAnnotations.Resources;
using System.Diagnostics.CodeAnalysis;
namespace System.ComponentModel.DataAnnotations {
/// <summary>
/// Validation attribute to indicate that a property field or parameter is required.
/// </summary>
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
[SuppressMessage("Microsoft.Performance", "CA1813:AvoidUnsealedAttributes", Justification = "We want users to be able to extend this class")]
public class RequiredAttribute : ValidationAttribute {
/// <summary>
/// Default constructor.
/// </summary>
/// <remarks>This constructor selects a reasonable default error message for <see cref="ValidationAttribute.FormatErrorMessage"/></remarks>
public RequiredAttribute()
: base(() => DataAnnotationsResources.RequiredAttribute_ValidationError) {
}
/// <summary>
/// Gets or sets a flag indicating whether the attribute should allow empty strings.
/// </summary>
public bool AllowEmptyStrings { get; set; }
/// <summary>
/// Override of <see cref="ValidationAttribute.IsValid(object)"/>
/// </summary>
/// <param name="value">The value to test</param>
/// <returns><c>false</c> if the <paramref name="value"/> is null or an empty string. If <see cref="RequiredAttribute.AllowEmptyStrings"/>
/// then <c>false</c> is returned only if <paramref name="vale"/> is null.</returns>
#if !SILVERLIGHT
public
#else
internal
#endif
override bool IsValid(object value) {
if (value == null) {
return false;
}
// only check string length if empty strings are not allowed
var stringValue = value as string;
if (stringValue != null && !AllowEmptyStrings) {
return stringValue.Trim().Length != 0;
}
return true;
}
}
}
|
