add select by type

Author: Harish

QueryBuilder.Tests/SelectTests.cs

@@ -958,5 +958,35 @@ public void SelectWithExists_OmitSelectIsFalse()
             Assert.Equal("SELECT * FROM [Posts] WHERE EXISTS (SELECT [Id] FROM [Comments] WHERE [Comments].[PostId] = [Posts].[Id])", sqlServer.ToString());
         }
 
+        public record Post(int Id, string Title, DateTime Published);
+
+        [Fact]
+        public void SelectType() {
+            var q = new Query("Post").Select<Post>();
+
+            var pgsql = Compilers.CompileFor(EngineCodes.PostgreSql, q);
+
+            Assert.Equal("""
+                         SELECT "Id", "Title", "Published" FROM "Post"
+                         """, pgsql.ToString());
+        }
+
+        public class Comment {
+            [Column("comment_id")] public int Id { get; set; }
+            [Column("post_id")] public int PostId { get; set; }
+            [Column("content")] public string Content { get; set; }
+            [Column("created_at")] public DateTime Created { get; set; }
+        }
+
+        [Fact]
+        public void SelectType_WithColumnAttribute() {
+            var q = new Query("Comment").Select<Comment>();
+
+            var pgsql = Compilers.CompileFor(EngineCodes.PostgreSql, q);
+
+            Assert.Equal("""
+                         SELECT "comment_id" AS "Id", "post_id" AS "PostId", "content" AS "Content", "created_at" AS "Created" FROM "Comment"
+                         """, pgsql.ToString());
+        }
     }
 }

QueryBuilder/Query.Select.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Reflection;
 
 namespace SqlKata
 {
@@ -117,5 +118,24 @@ public Query SelectMax(string column, Func<Query, Query> filter = null)
         {
             return SelectAggregate("max", column, filter);
         }
+
+        public Query Select<T>() {
+            var properties = typeof(T).GetProperties();
+            var columns = new List<string>();
+            foreach (var property in properties) {
+                if (property.GetSetMethod() == null) {
+                    continue;
+                }
+
+                var name = property.Name;
+                var attribute = property.GetCustomAttribute<ColumnAttribute>();
+                if (attribute != null) {
+                    name = $"{attribute.Name} as {name}";
+                }
+
+                columns.Add(name);
+            }
+            return Select(columns);
+        }
     }
 }