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MongoQueryTranslator.cs
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MongoQueryTranslator.cs
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/* Copyright 2010-present MongoDB Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
namespace MongoDB.Driver.Linq
{
/// <summary>
/// A translator from LINQ expression queries to Mongo queries.
/// </summary>
public static class MongoQueryTranslator
{
// public static methods
/// <summary>
/// Translate a MongoDB LINQ query.
/// </summary>
/// <param name="query">The MongoDB LINQ query.</param>
/// <returns>A TranslatedQuery.</returns>
public static TranslatedQuery Translate(IQueryable query)
{
return Translate((MongoQueryProvider)query.Provider, query.Expression);
}
/// <summary>
/// Translate a MongoDB LINQ query.
/// </summary>
/// <param name="provider">The MongoDB query provider.</param>
/// <param name="expression">The LINQ query expression.</param>
/// <returns>A TranslatedQuery.</returns>
public static TranslatedQuery Translate(MongoQueryProvider provider, Expression expression)
{
expression = PartialEvaluator.Evaluate(expression, provider);
expression = ExpressionNormalizer.Normalize(expression);
// assume for now it's a SelectQuery
var documentType = GetDocumentType(expression);
var selectQuery = new SelectQuery(provider.Collection, documentType);
selectQuery.Translate(expression);
return selectQuery;
}
// private static methods
private static Type GetDocumentType(Expression expression)
{
// look for the innermost nested constant of type MongoQueryable<T> and return typeof(T)
var constantExpression = expression as ConstantExpression;
if (constantExpression != null)
{
var constantType = constantExpression.Type;
var constantTypeInfo = constantType.GetTypeInfo();
if (constantTypeInfo.IsGenericType)
{
var genericTypeDefinition = constantTypeInfo.GetGenericTypeDefinition();
if (genericTypeDefinition == typeof(MongoQueryable<>))
{
return constantTypeInfo.GetGenericArguments()[0];
}
}
}
var methodCallExpression = expression as MethodCallExpression;
if (methodCallExpression != null && methodCallExpression.Arguments.Count != 0)
{
return GetDocumentType(methodCallExpression.Arguments[0]);
}
var message = string.Format("Unable to find document type of expression: {0}.", ExpressionFormatter.ToString(expression));
throw new ArgumentOutOfRangeException("expression", message);
}
}
}