我希望实现一个系统,用于“构建”条件,然后从数据库返回结果数据.目前,有一个存储过程可以动态生成sql并执行它.这是我想要删除的特殊问题.
我的问题来自这样一个事实:我可以在我的标准中包含多个字段,并且对于每个字段,可能有一个或多个值,具有不同的潜在运算符.
例如,
from t in Contacts where t.Email == "email@domain.com" || t.Email.Contains ("mydomain") where t.Field1 == "valuewewant" where t.Field2 != "valuewedontwant" select t
字段,标准和运算符存储在数据库中(和List< FieldCriteria>)并且可能是这样的(基于上面);
Email,Equals,"email@domain.com" Email,Contains,"mydomain" Field1,"valuewewant" Field2,DoesNotEqual,"valuewedontwant"
要么
new FieldCriteria { FieldName = "Email",Operator = 1,Value = "email@mydomain.com" }
因此,使用我拥有的信息,我希望能够构建具有任意数量条件的查询.我之前看到过Dynamic Linq和PredicateBuilder的链接,但我无法将其视为我自己问题的解决方案.
任何建议,将不胜感激.
更新
继关于Dynamic Linq的建议之后,我提出了一个非常基本的解决方案,使用单个运算符,具有2个字段和多个条件.目前在LinqPad中编写的有点粗略,但结果正是我想要的;
enum Operator { Equals = 1,} class Condition { public string Field { get; set; } public Operator Operator { get; set;} public string Value { get; set;} } void Main() { var conditions = new List<Condition>(); conditions.Add(new Condition { Field = "Email",Operator = Operator.Equals,Value = "email1@domain.com" }); conditions.Add(new Condition { Field = "Email",Value = "email2@domain.com" }); conditions.Add(new Condition { Field = "Field1",Value = "Chris" }); var statusConditions = "Status = 1"; var emailConditions = from c in conditions where c.Field == "Email" select c; var field1Conditions = from c in conditions where c.Field == "Field1" select c; var emailConditionsFormatted = from c in emailConditions select string.Format("Email=\"{0}\"",c.Value); var field1ConditionsFormatted = from c in field1Conditions select string.Format("Field1=\"{0}\"",c.Value); string[] conditionsArray = emailConditionsFormatted.ToArray(); var emailConditionsJoined = string.Join("||",conditionsArray); Console.WriteLine(String.Format("Formatted Condition For Email: {0}",emailConditionsJoined)); conditionsArray = field1ConditionsFormatted.ToArray(); var field1ConditionsJoined = string.Join("||",conditionsArray); Console.WriteLine(String.Format("Formatted Condition For Field1: {0}",field1ConditionsJoined)); IQueryable results = ContactView.Where(statusConditions); if (emailConditions != null) { results = results.Where(emailConditionsJoined); } if (field1Conditions != null) { results = results.Where(field1ConditionsJoined); } results = results.Select("id"); foreach (int id in results) { Console.WriteLine(id.ToString()); } }
-- Region Parameters DECLARE @p0 VarChar(1000) = 'Chris' DECLARE @p1 VarChar(1000) = 'email1@domain.com' DECLARE @p2 VarChar(1000) = 'email2@domain.com' DECLARE @p3 Int = 1 -- EndRegion SELECT [t0].[id] FROM [Contacts].[ContactView] AS [t0] WHERE ([t0].[field1] = @p0) AND (([t0].[email] = @p1) OR ([t0].[email] = @p2)) AND ([t0].[status] = @p3)
和控制台输出:
Formatted Condition For Email: Email="email1@domain.com"||Email="email2@domain.com" Formatted Condition For Field1: Field1="Chris"
只需要清理它并添加其他操作符,它看起来不错.
如果到目前为止任何人对此有任何意见,任何意见将不胜感激