扩展MongoDB C# Driver的QueryBuilder

扩展mongodb c# driver的querybuilder

由于不想直接hardcode "classa.membera.memberb" 这样的字符串 ，写了以下几个类，用于以下常用的场景：
1. 表达式转换成字符串函数： exptostr()
2. collection函数：当有集合成员时，可以使用此类，将返回querycollection对象，这个类的代码之后附上
3. collectionas函数：当使用了继承，希望将基类转换为子类并返回子类的querycollection
使用示例：

//获得表达式的字符串形式
1. QueryEx.ExpToStr ((ClassA m)=> m.MemberA.MemberB.MemberC)


//集合.成员.字段
//PoppedSegments为集合，AssignedNetwork.Name为成员
//将返回PoppedSegments.AssignedNetwork.Name
2. QueryEx.Collection(x => x.PoppedSegments).Matches(p => p.AssignedNetwork.Name, bsonRegex),


//子类集合.成员.字段
//STPaymentTransaction为基类，STPaymentCompanyCredit为子类，Company字段在子类中
//将返回Payments.Company.Name
3. QueryEx.CollectionAs(x=>x.Payments).Matches(p=>p.Company.Name, bsonRegex)


//集合.集合.成员.字段
//Parcels为集合，STCustomPropertyRuntime为基类，STNumericPropertyRuntime为子类，CustomProps为STNumericPropertyRuntime中成员，Value为CustomProp中成员
//将返回Parcels.CustomProps.Value
4. QueryEx.Collection(x=>x.Parcels).CollectionMemberAs(p=>p.CustomProps).Matches(p=>p.Value, bsonRegex),

实现代码：

public class QueryEx
    {
        public static QueryCollection Collection(
            Expression>> collectionExpression)
        {
            return new QueryCollection(collectionExpression);
        }


        //for those cases using inheritance
        //e.g STPaymentTransaction
        //Payments will return STPaymentTransaction 
        //need to cast to sub classes(STPaymentCompanyCredit) so that be able to filter by child members (e.g. Company)
        public static QueryCollection CollectionAs(
            Expression>> collectionExpression)
            where TSub : TCollection
        {
            var argParam = Expression.Parameter(typeof (TDocument), "x");
            var memberStr = ExpToStr(collectionExpression);
            MemberExpression nameProperty = Expression.Property(argParam, memberStr);


            var subExp = Expression.Convert(nameProperty, typeof(IEnumerable));


            var exp = Expression.Lambda>>(
                subExp,
                argParam);


            return new QueryCollection(exp);
        }


        /// 

        /// return string value for a expression:
        /// for s.Name.Val1.Val2 will return Name.Val1.Val2
        /// 
        /// 
        /// 
        /// 
        /// 
        public static string ExpToStr(Expression> exp)
        {
            return new QueryExpressionHelper().MemberExpression(exp);
        }
    }








public class QueryCollection
    {
        private readonly QueryExpressionHelper _queryExpression;
        private string _collectionName;


        public string Context
        {
            get { return _collectionName; }
        }


        public QueryCollection(Expression>> collectionExpression)
        {
            _queryExpression = new QueryExpressionHelper();
            _collectionName = _queryExpression.MemberExpression(collectionExpression);
        }


        public QueryMember Member(Expression> exp)
        {
            var expStr = QueryEx.ExpToStr(exp);
            var context = string.Format("{0}.{1}", _collectionName, expStr);
            var obj = new QueryMember(context);


            return obj;
        }


        public QueryCollection CollectionMember(
            Expression>> exp)
        {
            var expStr = QueryEx.ExpToStr(exp);
            var obj = new QueryCollection(exp)
            {
                _collectionName = string.Format("{0}.{1}", _collectionName, expStr)
            };


            return obj;
        }


        /// 

        /// this method only support 1 layer nested(not for Query Collection.Collection , but for Collection.Member)
        /// if member is collection and need convert to sub class 
        /// 
        /// Base Type
        /// Child Class Type
        /// 
        /// 
        public QueryCollection CollectionMemberAs(
            Expression>> collectionExpression)
            where TMemberSub : TMember
        {
            var obj = QueryEx.CollectionAs(collectionExpression);
            obj._collectionName = string.Format("{0}.{1}", _collectionName, obj._collectionName);


            return obj;
        }


        public IMongoQuery LT(Expression> memberExpression, TMember value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.LT(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value));
        }


        public IMongoQuery LT(Expression>> memberExpression, TValue value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.LT(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value));
        }


        public IMongoQuery EQ(Expression> memberExpression, TMember value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.EQ(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value));
        }


        public IMongoQuery EQ(Expression>> memberExpression, TValue value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.EQ(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value));
        }


        public IMongoQuery NE(Expression> memberExpression, TMember value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.NE(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value));
        }


        public IMongoQuery NE(Expression>> memberExpression, TValue value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.NE(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value));
        }


        public IMongoQuery In(Expression> memberExpression, params TMember[] values)
        {
            return In(memberExpression, new List(values));
        }


        public IMongoQuery In(Expression> memberExpression,
            IEnumerable values)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);
            return Query.In(string.Format("{0}.{1}", _collectionName, memberName), values.Select(x => BsonValue.Create(x)));
        }


        public IMongoQuery In(Expression> memberExpression,
            IEnumerable values) where TCastC : TCollection
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);
            return Query.In(string.Format("{0}.{1}", _collectionName, memberName), values.Select(x => BsonValue.Create(x)));
        }


        public IMongoQuery In(Expression>> memberExpression, IEnumerable values)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);
            return Query.In(string.Format("{0}.{1}", _collectionName, memberName), values.Select(x => BsonValue.Create(x)));
        }


        public IMongoQuery In(Expression>> memberExpression, IEnumerable values) where TCastC : TCollection
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);
            return Query.In(string.Format("{0}.{1}", _collectionName, memberName), values.Select(x => BsonValue.Create(x)));
        }




        public IMongoQuery Matches(Expression> memberExpression, BsonRegularExpression value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.Matches(string.Format("{0}.{1}", _collectionName, memberName), value);
        }


        public IMongoQuery Matches(Expression>> memberExpression, BsonRegularExpression value)
        {
            var memberName = _queryExpression.MemberExpression(memberExpression);


            return Query.Matches(string.Format("{0}.{1}", _collectionName, memberName), value);
        }
    }








public class QueryMember
    {
        private readonly QueryExpressionHelper _queryExpression;
        private string _collectionName;


        public string Context
        {
            get { return _collectionName; }
        }


        public QueryMember(Expression> exp)
        {
            _queryExpression = new QueryExpressionHelper();
            _collectionName = _queryExpression.MemberExpression(exp);
        }


        public QueryMember(string context)
        {
            _collectionName = context;
        }


    }




public class QueryExpressionHelper
    {
        public string Context;


        public string MemberExpression(Expression expression)
        {
            MemberExpression me;
            switch (expression.Body.NodeType)
            {
                case ExpressionType.MemberAccess:
                    me = expression.Body as MemberExpression;
                    break;
                case ExpressionType.Convert:
                    dynamic convertedBody = expression.Body;
                    me = convertedBody.Operand as MemberExpression;
                    break;


                default:
                    throw new NotSupportedException(string.Format("Member with node type {0} is not supported. expression {1}", 
                    expression.Body.NodeType, expression));
            }
            var stack = new Stack();


            while (me != null)
            {
                stack.Push(me.Member.Name);
                me = me.Expression as MemberExpression;
            }


            var expStr = string.Join(".", stack.ToArray());
            return expStr;


           
        }
    }




public static class QueryMoney
    {
        public static IMongoQuery Value(string name, double val)
        {
            var accuracy = 0.005;


            return Query.And(
                Query.LT(name, new BsonDouble(val + accuracy)),
                Query.GT(name, new BsonDouble(val - accuracy)));
        }
    }

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