转移.net core 3.1，为.NET 5做准备

Infrastructure/Extensions/GenericExtension.cs

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+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
+
+namespace Infrastructure.Extensions
+{
+    /// <summary>
+    /// 泛型扩展
+    /// </summary>
+    public static class GenericExtension
+    {
+        public static bool Equal<T>(this T x, T y)
+        {
+            return ((IComparable)(x)).CompareTo(y) == 0;
+        }
+
+        #region ToDictionary
+        /// <summary>
+        /// 将实体指定的字段写入字典
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="t"></param>
+        /// <param name="expression"></param>
+        /// <returns></returns>
+
+        public static Dictionary<string, object> ToDictionary<T>(this T t, Expression<Func<T, object>> expression) where T : class
+        {
+            Dictionary<string, object> dic = new Dictionary<string, object>();
+            string[] fields = expression.GetExpressionToArray();
+            PropertyInfo[] properties = expression == null ? t.GetType().GetProperties() : t.GetType().GetProperties().Where(x => fields.Contains(x.Name)).ToArray();
+
+            foreach (var property in properties)
+            {
+                var value = property.GetValue(t, null);
+                dic.Add(property.Name, value != null ? value.ToString() : "");
+            }
+            return dic;
+        }
+
+        public static Dictionary<string, string> ToDictionary<TInterface, T>(this TInterface t, Dictionary<string, string> dic = null) where T : class, TInterface
+        {
+            if (dic == null)
+                dic = new Dictionary<string, string>();
+            var properties = typeof(T).GetProperties();
+            foreach (var property in properties)
+            {
+                var value = property.GetValue(t, null);
+                if (value == null) continue;
+                dic.Add(property.Name, value != null ? value.ToString() : "");
+            }
+            return dic;
+        }
+
+        #endregion
+
+
+        public static DataTable ToDataTable<T>(this IEnumerable<T> source, Expression<Func<T, object>> columns = null, bool contianKey = true)
+        {
+            DataTable dtReturn = new DataTable();
+            if (source == null) return dtReturn;
+
+            PropertyInfo[] oProps = typeof(T).GetProperties()
+                .Where(x => x.PropertyType.Name != "List`1").ToArray();
+            if (columns != null)
+            {
+                string[] columnArray = columns.GetExpressionToArray();
+                oProps = oProps.Where(x => columnArray.Contains(x.Name)).ToArray();
+            }
+            //移除自增主键
+            PropertyInfo keyType = oProps.GetKeyProperty();// oProps.GetKeyProperty()?.PropertyType;
+            if (!contianKey && keyType != null && (keyType.PropertyType == typeof(int) || keyType.PropertyType == typeof(long)))
+            {
+                oProps = oProps.Where(x => x.Name != keyType.Name).ToArray();
+            }
+
+            foreach (var pi in oProps)
+            {
+                var colType = pi.PropertyType;
+
+                if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() == typeof(Nullable<>)))
+                {
+                    colType = colType.GetGenericArguments()[0];
+                }
+
+                dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
+            }
+            foreach (var rec in source)
+            {
+                var dr = dtReturn.NewRow();
+                foreach (var pi in oProps)
+                {
+                    dr[pi.Name] = pi.GetValue(rec, null) == null
+                        ? DBNull.Value
+                        : pi.GetValue
+                            (rec, null);
+                }
+                dtReturn.Rows.Add(dr);
+            }
+            return dtReturn;
+        }
+    }
+}