基于领域驱动设计(DDD)超轻量级快速开发架构(二)动态linq查询的实现方式
-之动态查询,查询逻辑封装复用
https://www.cnblogs.com/neozhu/p/13174234.html
需求
- 配合EasyUI datagird filter实现多字段(任意字段)的筛选
- 根据业务需求筛选特定的状态或条件,如:查看结案的订单,最近30天的订单,查看属于我的订单.等等,这些逻辑是固定也是可以被重用,但又不想每次写相同的条件,那么下面我会给我的解决方案.
需求1只是一个偷懒的实现方式,因为datagrid自带这个功能,但又不想根据具体的需求来画查询条件,如果需求必须要再datagrid上面做一块查询条件的输入那目前只能在前端自己手工添加,在组织后传入后台,暂时不在这里讨论
需求2可能不太好解释,看完代码就自然理解为什么要这么做了,这么做的好处有哪些
具体实现的方式
默认情况下 datagrid 有几列就可以对这几列进行筛选,对于日期型的字段会采用between,选择2个时间之间进行筛选,数字类型会提供大于小于等符号选择,可以自行尝试,其原理是datagrid 会根据datagrid 头部输入的值生成一个Json字符串发送后台请求数据
JSON:格式
filterRules: [
{field:field,op:op,value:value},{field:field,op:op,value:value},]
- 通常的做法是一个一个判断加条件
1 var filters = JsonConvert.DeserializeObject<IEnumerable<filterRule>>(filterRules); 2 foreach (var rule in filters) 3 { 4 if (rule.field == "Id" && !string.IsNullOrEmpty(rule.value) && rule.value.IsInt()) 5 { 6 var val = Convert.ToInt32(rule.value); 7 switch (rule.op) 8 { 9 case "equal": 10 this.And(x => x.Id == val); 11 break; 12 case "notequal": 13 this.And(x => x.Id != val); 14 break; 15 case "less": 16 this.And(x => x.Id < val); 17 break; 18 case "lessorequal": 19 this.And(x => x.Id <= val); 20 break; 21 case "greater": 22 this.And(x => x.Id > val); 23 break; 24 case "greaterorequal": 25 this.And(x => x.Id >= val); 26 break; 27 default: 28 this.And(x => x.Id == val); 29 break; 30 } 31 } 32 if (rule.field == "Name" && !string.IsNullOrEmpty(rule.value)) 33 { 34 this.And(x => x.Name.Contains(rule.value)); 35 } 36 if (rule.field == "Code" && !string.IsNullOrEmpty(rule.value)) 37 { 38 this.And(x => x.Code.Contains(rule.value)); 39 } 40 41 if (rule.field == "Address" && !string.IsNullOrEmpty(rule.value)) 42 { 43 this.And(x => x.Address.Contains(rule.value)); 44 } 45 46 if (rule.field == "Contect" && !string.IsNullOrEmpty(rule.value)) 47 { 48 this.And(x => x.Contect.Contains(rule.value)); 49 } 50 51 if (rule.field == "PhoneNumber" && !string.IsNullOrEmpty(rule.value)) 52 { 53 this.And(x => x.PhoneNumber.Contains(rule.value)); 54 } 55 56 if (rule.field == "RegisterDate" && !string.IsNullOrEmpty(rule.value)) 57 { 58 if (rule.op == "between") 59 { 60 var datearray = rule.value.Split(new char[] { '-' }); 61 var start = Convert.ToDateTime(datearray[0]); 62 var end = Convert.ToDateTime(datearray[1]); 63 64 this.And(x => SqlFunctions.DateDiff("d", start, x.RegisterDate) >= 0); 65 this.And(x => SqlFunctions.DateDiff("d", end, x.RegisterDate) <= 0); 66 } 67 } 68 if (rule.field == "CreatedDate" && !string.IsNullOrEmpty(rule.value)) 69 { 70 if (rule.op == "between") 71 { 72 var datearray = rule.value.Split(new char[] { '-' }); 73 var start = Convert.ToDateTime(datearray[0]); 74 var end = Convert.ToDateTime(datearray[1]); 75 76 this.And(x => SqlFunctions.DateDiff("d", start, x.CreatedDate) >= 0); 77 this.And(x => SqlFunctions.DateDiff("d", end, x.CreatedDate) <= 0); 78 } 79 } 80 81 82 if (rule.field == "CreatedBy" && !string.IsNullOrEmpty(rule.value)) 83 { 84 this.And(x => x.CreatedBy.Contains(rule.value)); 85 } 86 87 if (rule.field == "LastModifiedDate" && !string.IsNullOrEmpty(rule.value)) 88 { 89 if (rule.op == "between") 90 { 91 var datearray = rule.value.Split(new char[] { '-' }); 92 var start = Convert.ToDateTime(datearray[0]); 93 var end = Convert.ToDateTime(datearray[1]); 94 95 this.And(x => SqlFunctions.DateDiff("d", start, x.LastModifiedDate) >= 0); 96 this.And(x => SqlFunctions.DateDiff("d", end, x.LastModifiedDate) <= 0); 97 } 98 } 99 100 if (rule.field == "LastModifiedBy" && !string.IsNullOrEmpty(rule.value)) 101 { 102 this.And(x => x.LastModifiedBy.Contains(rule.value)); 103 } 104 105 }
- 新的做法是动态根据field,op,value生成一个linq 表达式,不用再做繁琐的判断,这块代码也可以被其它项目使用,非常好用
namespace SmartAdmin { public static class PredicateBuilder { public static Expression<Func<T, bool>> FromFilter<T>(string filtergroup) { Expression<Func<T, bool>> any = x => true; if (!string.IsNullOrEmpty(filtergroup)) { var filters = JsonSerializer.Deserialize<filter[]>(filtergroup); foreach (var filter in filters) { if (Enum.TryParse(filter.op, out OperationExpression op) && !string.IsNullOrEmpty(filter.value)) { var expression = GetCriteriaWhere<T>(filter.field, op, filter.value); any = any.And(expression); } } } return any; } #region -- Public methods -- public static Expression<Func<T, bool>> GetCriteriaWhere<T>(Expression<Func<T, object>> e, OperationExpression selectedOperator, object fieldValue) { var name = GetOperand<T>(e); return GetCriteriaWhere<T>(name, selectedOperator, fieldValue); } public static Expression<Func<T, bool>> GetCriteriaWhere<T, T2>(Expression<Func<T, object>> e, OperationExpression selectedOperator, object fieldValue) { var name = GetOperand<T>(e); return GetCriteriaWhere<T, T2>(name, selectedOperator, fieldValue); } public static Expression<Func<T, bool>> GetCriteriaWhere<T>(string fieldName, OperationExpression selectedOperator, object fieldValue) { var props = TypeDescriptor.GetProperties(typeof(T)); var prop = GetProperty(props, fieldName, true); var parameter = Expression.Parameter(typeof(T)); var expressionParameter = GetMemberExpression<T>(parameter, fieldName); if (prop != null && fieldValue != null) { BinaryExpression body = null; switch (selectedOperator) { case OperationExpression.equal: body = Expression.Equal(expressionParameter, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType)?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(body, parameter); case OperationExpression.notequal: body = Expression.NotEqual(expressionParameter, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(body, parameter); case OperationExpression.less: body = Expression.LessThan(expressionParameter, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(body, parameter); case OperationExpression.lessorequal: body = Expression.LessThanOrEqual(expressionParameter, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(body, parameter); case OperationExpression.greater: body = Expression.GreaterThan(expressionParameter, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(body, parameter); case OperationExpression.greaterorequal: body = Expression.GreaterThanOrEqual(expressionParameter, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(body, parameter); case OperationExpression.contains: var contains = typeof(string).GetMethod("Contains", new[] { typeof(string) }); var bodyLike = Expression.Call(expressionParameter, contains, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(bodyLike, parameter); case OperationExpression.endwith: var endswith = typeof(string).GetMethod("EndsWith",new[] { typeof(string) }); var bodyendwith = Expression.Call(expressionParameter, endswith, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(bodyendwith, parameter); case OperationExpression.beginwith: var startswith = typeof(string).GetMethod("StartsWith", new[] { typeof(string) }); var bodystartswith = Expression.Call(expressionParameter, startswith, Expression.Constant(Convert.ChangeType(fieldValue, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType), prop.PropertyType)); return Expression.Lambda<Func<T, bool>>(bodystartswith, parameter); case OperationExpression.includes: return Includes<T>(fieldValue, parameter, expressionParameter, prop.PropertyType); case OperationExpression.between: return Between<T>(fieldValue, parameter, expressionParameter, prop.PropertyType); default: throw new Exception("Not implement Operation"); } } else { Expression<Func<T, bool>> filter = x => true; return filter; } } public static Expression<Func<T, bool>> GetCriteriaWhere<T, T2>(string fieldName, OperationExpression selectedOperator, object fieldValue) { var props = TypeDescriptor.GetProperties(typeof(T)); var prop = GetProperty(props, fieldName, true); var parameter = Expression.Parameter(typeof(T)); var expressionParameter = GetMemberExpression<T>(parameter, fieldName); if (prop != null && fieldValue != null) { switch (selectedOperator) { case OperationExpression.any: return Any<T, T2>(fieldValue, parameter, expressionParameter); default: throw new Exception("Not implement Operation"); } } else { Expression<Func<T, bool>> filter = x => true; return filter; } } public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr, Expression<Func<T, bool>> or) { if (expr == null) { return or; } return Expression.Lambda<Func<T, bool>>(Expression.OrElse(new SwapVisitor(expr.Parameters[0], or.Parameters[0]).Visit(expr.Body), or.Body), or.Parameters); } public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expr, Expression<Func<T, bool>> and) { if (expr == null) { return and; } return Expression.Lambda<Func<T, bool>>(Expression.AndAlso(new SwapVisitor(expr.Parameters[0], and.Parameters[0]).Visit(expr.Body), and.Body), and.Parameters); } #endregion #region -- Private methods -- private static string GetOperand<T>(Expression<Func<T, object>> exp) { if (!( exp.Body is MemberExpression body )) { var ubody = (UnaryExpression)exp.Body; body = ubody.Operand as MemberExpression; } var operand = body.ToString(); return operand.Substring(2); } private static MemberExpression GetMemberExpression<T>(ParameterExpression parameter, string propName) { if (string.IsNullOrEmpty(propName)) { return null; } var propertiesName = propName.Split('.'); if (propertiesName.Count() == 2) { return Expression.Property(Expression.Property(parameter, propertiesName[0]), propertiesName[1]); } return Expression.Property(parameter, propName); } private static Expression<Func<T, bool>> Includes<T>(object fieldValue, ParameterExpression parameterExpression, MemberExpression memberExpression ,Type type) { var safetype= Nullable.GetUnderlyingType(type) ?? type; switch (safetype.Name.ToLower()) { case "string": var strlist = (IEnumerable<string>)fieldValue; if (strlist == null || strlist.Count() == 0) { return x => true; } var strmethod = typeof(List<string>).GetMethod("Contains", new Type[] { typeof(string) }); var strcallexp = Expression.Call(Expression.Constant(strlist.ToList()), strmethod, memberExpression); return Expression.Lambda<Func<T, bool>>(strcallexp, parameterExpression); case "int32": var intlist = (IEnumerable<int>)fieldValue; if (intlist == null || intlist.Count() == 0) { return x => true; } var intmethod = typeof(List<int>).GetMethod("Contains", new Type[] { typeof(int) }); var intcallexp = Expression.Call(Expression.Constant(intlist.ToList()), intmethod, memberExpression); return Expression.Lambda<Func<T, bool>>(intcallexp, parameterExpression); case "float": var floatlist = (IEnumerable<float>)fieldValue; if (floatlist == null || floatlist.Count() == 0) { return x => true; } var floatmethod = typeof(List<int>).GetMethod("Contains", new Type[] { typeof(int) }); var floatcallexp = Expression.Call(Expression.Constant(floatlist.ToList()), floatmethod, memberExpression); return Expression.Lambda<Func<T, bool>>(floatcallexp, parameterExpression); default: return x => true; } } private static Expression<Func<T, bool>> Between<T>(object fieldValue, ParameterExpression parameterExpression, MemberExpression memberExpression, Type type) { var safetype = Nullable.GetUnderlyingType(type) ?? type; switch (safetype.Name.ToLower()) { case "datetime": var datearray = ( (string)fieldValue ).Split(new char[] { '-' }, StringSplitOptions.RemoveEmptyEntries); var start = Convert.ToDateTime(datearray[0] + " 00:00:00", CultureInfo.CurrentCulture); var end = Convert.ToDateTime(datearray[1] + " 23:59:59", CultureInfo.CurrentCulture); var greater = Expression.GreaterThan(memberExpression, Expression.Constant(start, type)); var less = Expression.LessThan(memberExpression, Expression.Constant(end, type)); return Expression.Lambda<Func<T, bool>>(greater, parameterExpression) .And(Expression.Lambda<Func<T, bool>>(less, parameterExpression)); case "int": case "int32": var intarray = ( (string)fieldValue ).Split(new char[] { '-' }, StringSplitOptions.RemoveEmptyEntries); var min = Convert.ToInt32(intarray[0] , CultureInfo.CurrentCulture); var max = Convert.ToInt32(intarray[1], CultureInfo.CurrentCulture); var maxthen = Expression.GreaterThan(memberExpression, Expression.Constant(min, type)); var minthen = Expression.LessThan(memberExpression, Expression.Constant(max, type)); return Expression.Lambda<Func<T, bool>>(maxthen, parameterExpression) .And(Expression.Lambda<Func<T, bool>>(minthen, parameterExpression)); case "decimal": var decarray = ( (string)fieldValue ).Split(new char[] { '-' }, StringSplitOptions.RemoveEmptyEntries); var dmin = Convert.ToDecimal(decarray[0], CultureInfo.CurrentCulture); var dmax = Convert.ToDecimal(decarray[1], CultureInfo.CurrentCulture); var dmaxthen = Expression.GreaterThan(memberExpression, Expression.Constant(dmin, type)); var dminthen = Expression.LessThan(memberExpression, Expression.Constant(dmax, type)); return Expression.Lambda<Func<T, bool>>(dmaxthen, parameterExpression) .And(Expression.Lambda<Func<T, bool>>(dminthen, parameterExpression)); case "float": var farray = ((string)fieldValue).Split(new char[] { '-' }, StringSplitOptions.RemoveEmptyEntries); var fmin = Convert.ToDecimal(farray[0], CultureInfo.CurrentCulture); var fmax = Convert.ToDecimal(farray[1], CultureInfo.CurrentCulture); var fmaxthen = Expression.GreaterThan(memberExpression, Expression.Constant(fmin, type)); var fminthen = Expression.LessThan(memberExpression, Expression.Constant(fmax, type)); return Expression.Lambda<Func<T, bool>>(fmaxthen, parameterExpression) .And(Expression.Lambda<Func<T, bool>>(fminthen, parameterExpression)); case "string": var strarray = ( (string)fieldValue ).Split(new char[] { '-' }, StringSplitOptions.RemoveEmptyEntries); var smin = strarray[0]; var smax = strarray[1]; var strmethod = typeof(string).GetMethod("Contains"); var mm = Expression.Call(memberExpression, strmethod, Expression.Constant(smin, type)); var nn = Expression.Call(memberExpression, strmethod, Expression.Constant(smax, type)); return Expression.Lambda<Func<T, bool>>(mm, parameterExpression) .Or(Expression.Lambda<Func<T, bool>>(nn, parameterExpression)); default: return x => true; } } private static Expression<Func<T, bool>> Any<T, T2>(object fieldValue, ParameterExpression parameterExpression, MemberExpression memberExpression) { var lambda = (Expression<Func<T2, bool>>)fieldValue; var anyMethod = typeof(Enumerable).GetMethods(BindingFlags.Static | BindingFlags.Public) .First(m => m.Name == "Any" && m.GetParameters().Count() == 2).MakeGenericMethod(typeof(T2)); var body = Expression.Call(anyMethod, memberExpression, lambda); return Expression.Lambda<Func<T, bool>>(body, parameterExpression); } private static PropertyDescriptor GetProperty(PropertyDescriptorCollection props, string fieldName, bool ignoreCase) { if (!fieldName.Contains('.')) { return props.Find(fieldName, ignoreCase); } var fieldNameProperty = fieldName.Split('.'); return props.Find(fieldNameProperty[0], ignoreCase).GetChildProperties().Find(fieldNameProperty[1], ignoreCase); } #endregion } internal class SwapVisitor : ExpressionVisitor { private readonly Expression from, to; public SwapVisitor(Expression from, Expression to) { this.from = from; this.to = to; } public override Expression Visit(Expression node) => node == from ? to : base.Visit(node); } public enum OperationExpression { equal, notequal, less, lessorequal, greater, greaterorequal, contains, beginwith, endwith, includes, between, any } }
1 public async Task<JsonResult> GetData(int page = 1, int rows = 10, string sort = "Id", string order = "asc", string filterRules = "") 2 { 3 try 4 { 5 var filters = PredicateBuilder.FromFilter<Company>(filterRules); 6 var total = await this.companyService 7 .Query(filters) 8 .AsNoTracking() 9 .CountAsync() 10 ; 11 var pagerows = (await this.companyService 12 .Query(filters) 13 .AsNoTracking() 14 .OrderBy(n => n.OrderBy(sort, order)) 15 .Skip(page - 1).Take(rows) 16 .SelectAsync()) 17 .Select(n => new 18 { 19 Id = n.Id, 20 Name = n.Name, 21 Code = n.Code, 22 Address = n.Address, 23 Contect = n.Contect, 24 PhoneNumber = n.PhoneNumber, 25 RegisterDate = n.RegisterDate.ToString("yyyy-MM-dd HH:mm:ss") 26 }).ToList(); 27 var pagelist = new { total = total, rows = pagerows }; 28 return Json(pagelist); 29 } 30 catch(Exception e) { 31 throw e; 32 } 33 34 }
- 对于固定查询逻辑的封装和复用,当然除了复用还可以明显的提高代码的可读性.
public class OrderSalesQuery : QueryObject<Order> { public decimal Amount { get; set; } public string Country { get; set; } public DateTime FromDate { get; set; } public DateTime ToDate { get; set; } public override Expression<Func<Order, bool>> Query() { return (x => x.OrderDetails.Sum(y => y.UnitPrice) > Amount && x.OrderDate >= FromDate && x.OrderDate <= ToDate && x.ShipCountry == Country); } }
var orderRepository = new Repository<Order>(this); var orders = orderRepository .Query(new OrderSalesQuery(){ Amount = 100, Country = "USA", FromDate = DateTime.Parse("01/01/1996"), ToDate = DateTime.Parse("12/31/1996" ) }) .Select();
public class CustomerLogisticsQuery : QueryObject<Customer> { public CustomerLogisticsQuery FromCountry(string country) { Add(x => x.Country == country); return this; } public CustomerLogisticsQuery LivesInCity(string city) { Add(x => x.City == city); return this; } }
public class CustomerSalesQuery : QueryObject<Customer> { public CustomerSalesQuery WithPurchasesMoreThan(decimal amount) { Add(x => x.Orders .SelectMany(y => y.OrderDetails) .Sum(z => z.UnitPrice * z.Quantity) > amount); return this; } public CustomerSalesQuery WithQuantitiesMoreThan(decimal quantity) { Add(x => x.Orders .SelectMany(y => y.OrderDetails) .Sum(z => z.Quantity) > quantity); return this; } }
var customerRepository = new Repository<Customer>(this); var query1 = new CustomerLogisticsQuery() .LivesInCity("London"); var query2 = new CustomerSalesQuery() .WithPurchasesMoreThan(100) .WithQuantitiesMoreThan(10); customerRepository .Query(query1.And(query2)) .Select() .Dump();
以上这些都是改项目提供的方法,非常的好用
