Code-complete v2 vehicle API

PartSource.Services/Extensions/IQueryableExtensions.cs

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+using Microsoft.EntityFrameworkCore;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
+using System.Text;
+
+using static System.Linq.Expressions.Expression;
+
+
+namespace PartSource.Services.Extensions
+{
+	public static class IQueryableExtensions
+	{
+		public static IQueryable<T> ApplyQueryDto<T>(this IQueryable<T> queryable, T dto)
+		{
+			foreach (PropertyInfo property in typeof(T).GetProperties())
+			{
+				object value = property.GetValue(dto);
+
+				if (IsFilterableValue(value))
+				{
+					queryable = queryable.Where(property, value);
+				}
+			}
+
+			return queryable;
+		}
+
+		private static IQueryable<T> Where<T>(this IQueryable<T> queryable, PropertyInfo property, object value)
+		{
+			if (property == null || value == null)
+			{
+				return queryable;
+			}
+
+			MemberExpression functions = Property(null, typeof(EF).GetProperty(nameof(EF.Functions)));
+			MethodInfo likeMethodInfo = typeof(DbFunctionsExtensions).GetMethod(nameof(DbFunctionsExtensions.Like), new Type[] { functions.Type, typeof(string), typeof(string) });
+
+			ParameterExpression lambdaParameter = Parameter(typeof(T), "x");
+			Expression expressionProperty = Property(lambdaParameter, property.Name);
+
+			if (property.PropertyType != typeof(string))
+			{
+				expressionProperty = Call(expressionProperty, typeof(object).GetMethod(nameof(object.ToString), new Type[0]));
+			}
+
+			MethodCallExpression methodCall = Call(
+					   null,
+					   likeMethodInfo,
+					   functions,
+					   expressionProperty,
+					   Constant(value.ToString()));
+
+			return queryable.Where(Lambda<Func<T, bool>>(methodCall, lambdaParameter));
+		}
+
+		private static bool IsFilterableValue(object value)
+		{
+			switch (value)
+			{
+				case int i:
+					if (i == default) return false;
+					break;
+
+				case DateTime d:
+					if (d == default) return false;
+					break;
+
+				case string s:
+					if (string.IsNullOrEmpty(s)) return false;
+					break;
+
+				default:
+					if (value == null) return false;
+					break;
+			}
+
+			return true;
+		}
+	}
+}