修改一版

IRaCIS.Core.Infrastructure/_IRaCIS/IQueryableExtensions.cs

@@ -3,6 +3,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.EntityFrameworkCore;
 using System.Linq.Dynamic.Core;
+using System.Collections.Generic;
 
 namespace IRaCIS.Core.Infrastructure.Extention
 {
@@ -29,6 +30,25 @@ namespace IRaCIS.Core.Infrastructure.Extention
             }
         }
 
+        /// <summary>
+        /// 查询字符串 为null 返回string.Empty
+        /// </summary>
+        /// <typeparam name="TSource"></typeparam>
+        /// <param name="source"></param>
+        /// <returns></returns>
+        public static  string FirstIsNullReturnEmpty(this IEnumerable<string> source)
+        {
+            var result =  source.FirstOrDefault();
+
+            if (result == null || result == string.Empty)
+            {
+                return string.Empty;
+            }
+            else
+            {
+                return result;
+            }
+        }
 
     }
 }