Extending QueryBuilder of MongoDB C# Driver
Extending the MongoDB C# Driver's QueryBuilder
Since I don't want to directly hardcode strings like "ClassA.MemberA.MemberB", I wrote the following classes for the following common scenarios:
1. Convert expression to string function: ExpToStr()
2. Collection function: When there are collection members, you can use this class, which will return a QueryCollection object. The code of this class is appended
3. CollectionAs function: When inheritance is used, you want to convert the base class to a subclass and return the QueryCollection of the subclass
Usage example:
//获得表达式的字符串形式 1. QueryEx<ClassA>.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<MDDelivery>.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<MDDelivery>.CollectionAs<STPaymentTransaction, STPaymentCompanyCredit>(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<MDDelivery>.Collection(x=>x.Parcels).CollectionMemberAs<STCustomPropertyRuntime, STNumericPropertyRuntime>(p=>p.CustomProps).Matches(p=>p.Value, bsonRegex),
Implementation code:
public class QueryEx<TDocument> { public static QueryCollection<TDocument, TCollection> Collection<TCollection>( Expression<Func<TDocument, IEnumerable<TCollection>>> collectionExpression) { return new QueryCollection<TDocument, TCollection>(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<TDocument, TSub> CollectionAs<TCollection, TSub>( Expression<Func<TDocument, IEnumerable<TCollection>>> 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<TSub>)); var exp = Expression.Lambda<Func<TDocument, IEnumerable<TSub>>>( subExp, argParam); return new QueryCollection<TDocument, TSub>(exp); } /// <summary> /// return string value for a expression: /// for s.Name.Val1.Val2 will return Name.Val1.Val2 /// </summary> /// <typeparam name="MDClass"></typeparam> /// <typeparam name="Member"></typeparam> /// <param name="exp"></param> /// <returns></returns> public static string ExpToStr<TDocument, Member>(Expression<Func<TDocument, Member>> exp) { return new QueryExpressionHelper().MemberExpression(exp); } } public class QueryCollection<TDocument, TCollection> { private readonly QueryExpressionHelper _queryExpression; private string _collectionName; public string Context { get { return _collectionName; } } public QueryCollection(Expression<Func<TDocument, IEnumerable<TCollection>>> collectionExpression) { _queryExpression = new QueryExpressionHelper(); _collectionName = _queryExpression.MemberExpression(collectionExpression); } public QueryMember<TCollection, TMember> Member<TMember>(Expression<Func<TCollection, TMember>> exp) { var expStr = QueryEx<TCollection>.ExpToStr(exp); var context = string.Format("{0}.{1}", _collectionName, expStr); var obj = new QueryMember<TCollection, TMember>(context); return obj; } public QueryCollection<TCollection, TMember> CollectionMember<TMember>( Expression<Func<TCollection, IEnumerable<TMember>>> exp) { var expStr = QueryEx<TCollection>.ExpToStr(exp); var obj = new QueryCollection<TCollection, TMember>(exp) { _collectionName = string.Format("{0}.{1}", _collectionName, expStr) }; return obj; } /// <summary> /// 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 /// </summary> /// <typeparam name="TMember">Base Type</typeparam> /// <typeparam name="TMemberSub">Child Class Type</typeparam> /// <param name="collectionExpression"></param> /// <returns></returns> public QueryCollection<TCollection, TMemberSub> CollectionMemberAs<TMember, TMemberSub>( Expression<Func<TCollection, IEnumerable<TMember>>> collectionExpression) where TMemberSub : TMember { var obj = QueryEx<TCollection>.CollectionAs<TMember, TMemberSub>(collectionExpression); obj._collectionName = string.Format("{0}.{1}", _collectionName, obj._collectionName); return obj; } public IMongoQuery LT<TMember>(Expression<Func<TCollection, TMember>> memberExpression, TMember value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.LT(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value)); } public IMongoQuery LT<TValue>(Expression<Func<TCollection, IEnumerable<TValue>>> memberExpression, TValue value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.LT(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value)); } public IMongoQuery EQ<TMember>(Expression<Func<TCollection, TMember>> memberExpression, TMember value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.EQ(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value)); } public IMongoQuery EQ<TValue>(Expression<Func<TCollection, IEnumerable<TValue>>> memberExpression, TValue value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.EQ(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value)); } public IMongoQuery NE<TMember>(Expression<Func<TCollection, TMember>> memberExpression, TMember value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.NE(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value)); } public IMongoQuery NE<TValue>(Expression<Func<TCollection, IEnumerable<TValue>>> memberExpression, TValue value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.NE(string.Format("{0}.{1}", _collectionName, memberName), BsonValue.Create(value)); } public IMongoQuery In<TMember>(Expression<Func<TCollection, TMember>> memberExpression, params TMember[] values) { return In<TMember>(memberExpression, new List<TMember>(values)); } public IMongoQuery In<TMember>(Expression<Func<TCollection, TMember>> memberExpression, IEnumerable<TMember> values) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.In(string.Format("{0}.{1}", _collectionName, memberName), values.Select(x => BsonValue.Create(x))); } public IMongoQuery In<TCastC, TMember>(Expression<Func<TCastC, TMember>> memberExpression, IEnumerable<TMember> 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<TValue>(Expression<Func<TCollection, IEnumerable<TValue>>> memberExpression, IEnumerable<TValue> values) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.In(string.Format("{0}.{1}", _collectionName, memberName), values.Select(x => BsonValue.Create(x))); } public IMongoQuery In<TCastC, TValue>(Expression<Func<TCastC, IEnumerable<TValue>>> memberExpression, IEnumerable<TValue> 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<TMember>(Expression<Func<TCollection, TMember>> memberExpression, BsonRegularExpression value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.Matches(string.Format("{0}.{1}", _collectionName, memberName), value); } public IMongoQuery Matches<TValue>(Expression<Func<TCollection, IEnumerable<TValue>>> memberExpression, BsonRegularExpression value) { var memberName = _queryExpression.MemberExpression(memberExpression); return Query.Matches(string.Format("{0}.{1}", _collectionName, memberName), value); } } public class QueryMember<TDocument, TCollection> { private readonly QueryExpressionHelper _queryExpression; private string _collectionName; public string Context { get { return _collectionName; } } public QueryMember(Expression<Func<TDocument, TCollection>> exp) { _queryExpression = new QueryExpressionHelper(); _collectionName = _queryExpression.MemberExpression(exp); } public QueryMember(string context) { _collectionName = context; } } public class QueryExpressionHelper { public string Context; public string MemberExpression<TMember>(Expression<TMember> 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<string>(); 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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