I have a this get setter class:

public class GetSetterClass
{
    [Required]
    [DisplayName("Some_Display_Name_1")]
    public int SomeProperty1 { get; set; }

    [Required]
    public string SomeProperty2 { get; set; }
}

After extracting the property info of the class, I want to extract a property based on:

1. DisplayName
2. If no DisplayName attribute present, I want to get property info by DataFieldName

This is the code I already have:

string testString1 = "Some_Display_Name_1";
string testString2 = "SomeProperty2";
string testString = testString1;
prop = props.FirstOrDefault(t => ((
                    t.PropertyInfo.GetCustomAttributes<DisplayNameAttribute>()?.FirstOrDefault() as DisplayNameAttribute)
                     .DisplayName
                     .Equals(testString , StringComparison.OrdinalIgnoreCase) ||
                    t.DataFieldName.Equals(testString , StringComparison.OrdinalIgnoreCase)
                ))?.PropertyInfo;

Here is the outcome:

1. The property with the DisplayName is successfully extracted.
2. However, when I set teststring="SomeProperty2"; I get a null reference exception.

Please advise.

CodePudding user response：

Can you check this ?

Its look like DisplayName is null for SomeProperty2

props.FirstOrDefault(t => ((
                    t.PropertyInfo.GetCustomAttributes<DisplayNameAttribute>()?.FirstOrDefault() as DisplayNameAttribute)
                     .DisplayName
                     ?.Equals(testString , StringComparison.OrdinalIgnoreCase) ||
                    t.DataFieldName.Equals(testString , StringComparison.OrdinalIgnoreCase)
                ))?.PropertyInfo;

CodePudding user response：

I found the answer after exploring LINQ more. here it is

prop = props.FindAll( p => p.PropertyInfo.GetCustomAttributes(typeof(DisplayNameAttribute), true).Any())
                .FirstOrDefault(p => p.PropertyInfo.GetCustomAttributes(typeof(DisplayNameAttribute), true)
                .Cast<DisplayNameAttribute>()
                .Any(a => a.DisplayName.Equals(teststring, StringComparison.OrdinalIgnoreCase)))?.PropertyInfo ??
    props.FirstOrDefault(t => t.DataFieldName.Equals(teststring, StringComparison.OrdinalIgnoreCase))?.PropertyInfo;