// private methods
private void CombinePredicateWithWhereClause(MethodCallExpression methodCallExpression, LambdaExpression predicate)
{
if (predicate != null)
{
if (_projection != null)
{
var message = string.Format("{0} with predicate after a projection is not supported.", methodCallExpression.Method.Name);
throw new NotSupportedException(message);
}
if (_where == null)
{
_where = predicate;
return;
}
if (_where.Parameters.Count != 1)
{
throw new MongoInternalException("Where lambda expression should have one parameter.");
}
var whereBody = _where.Body;
var whereParameter = _where.Parameters[0];
if (predicate.Parameters.Count != 1)
{
throw new MongoInternalException("Predicate lambda expression should have one parameter.");
}
var predicateBody = predicate.Body;
var predicateParameter = predicate.Parameters[0];
// when using OfType the parameter types might not match (but they do have to be compatible)
ParameterExpression parameter;
if (predicateParameter.Type.IsAssignableFrom(whereParameter.Type))
{
predicateBody = ExpressionParameterReplacer.ReplaceParameter(predicateBody, predicateParameter, whereParameter);
parameter = whereParameter;
}
else if (whereParameter.Type.IsAssignableFrom(predicateParameter.Type))
{
whereBody = ExpressionParameterReplacer.ReplaceParameter(whereBody, whereParameter, predicateParameter);
parameter = predicateParameter;
}
else
{
throw new NotSupportedException("Can't combine existing where clause with new predicate because parameter types are incompatible.");
}
var combinedBody = Expression.AndAlso(whereBody, predicateBody);
_where = Expression.Lambda(combinedBody, parameter);
}
}
/// <summary>
/// Executes the translated Find query.
/// </summary>
/// <returns>The result of executing the translated Find query.</returns>
public override object Execute()
{
var query = BuildQuery();
if (_distinct)
{
return(ExecuteDistinct(query));
}
var cursor = Collection.FindAs(DocumentType, query);
if (_orderBy != null)
{
var sortBy = new SortByDocument();
foreach (var clause in _orderBy)
{
var keyExpression = clause.Key.Body;
var serializationInfo = _serializationInfoHelper.GetSerializationInfo(keyExpression);
var direction = (clause.Direction == OrderByDirection.Descending) ? -1 : 1;
sortBy.Add(serializationInfo.ElementName, direction);
}
cursor.SetSortOrder(sortBy);
}
if (_skip != null)
{
cursor.SetSkip(ToInt32(_skip));
}
if (_take != null)
{
cursor.SetLimit(ToInt32(_take));
}
var projection = _projection;
if (_ofType != null)
{
if (projection == null)
{
var paramExpression = Expression.Parameter(DocumentType, "x");
var convertExpression = Expression.Convert(paramExpression, _ofType);
projection = Expression.Lambda(convertExpression, paramExpression);
}
else
{
var paramExpression = Expression.Parameter(DocumentType, "x");
var convertExpression = Expression.Convert(paramExpression, _ofType);
var body = ExpressionParameterReplacer.ReplaceParameter(projection.Body, projection.Parameters[0], convertExpression);
projection = Expression.Lambda(body, paramExpression);
}
}
IEnumerable enumerable;
if (projection == null)
{
enumerable = cursor;
}
else
{
var lambdaType = projection.GetType();
var delegateType = lambdaType.GetGenericArguments()[0];
var sourceType = delegateType.GetGenericArguments()[0];
var resultType = delegateType.GetGenericArguments()[1];
var projectorType = typeof(Projector <,>).MakeGenericType(sourceType, resultType);
var compiledProjection = projection.Compile();
var projector = Activator.CreateInstance(projectorType, cursor, compiledProjection);
enumerable = (IEnumerable)projector;
}
if (_elementSelector != null)
{
return(_elementSelector(enumerable));
}
else
{
return(enumerable);
}
}
// public methods
/// <summary>
/// Replaces all occurences of one parameter with a different parameter.
/// </summary>
/// <param name="node">The expression containing the parameter that should be replaced.</param>
/// <param name="fromParameter">The from parameter.</param>
/// <param name="toExpression">The expression that replaces the parameter.</param>
/// <returns>The expression with all occurrences of the parameter replaced.</returns>
public static Expression ReplaceParameter(Expression node, ParameterExpression fromParameter, Expression toExpression)
{
var replacer = new ExpressionParameterReplacer(fromParameter, toExpression);
return(replacer.Visit(node));
}
/// <summary>
/// Executes the translated Find query.
/// </summary>
/// <returns>The result of executing the translated Find query.</returns>
public override object Execute()
{
if (_take.HasValue && _take.Value == 0)
{
var type = _ofType ?? DocumentType;
return(typeof(Enumerable).GetMethod("Empty").MakeGenericMethod(type).Invoke(null, null));
}
var query = BuildQuery();
if (_distinct != null)
{
return(ExecuteDistinct(query));
}
var cursor = Collection.FindAs(DocumentType, query);
if (_orderBy != null)
{
var sortBy = new SortByDocument();
foreach (var clause in _orderBy)
{
var keyExpression = clause.Key.Body;
var serializationInfo = _serializationInfoHelper.GetSerializationInfo(keyExpression);
var direction = (clause.Direction == OrderByDirection.Descending) ? -1 : 1;
sortBy.Add(serializationInfo.ElementName, direction);
}
cursor.SetSortOrder(sortBy);
}
if (_skip != null)
{
cursor.SetSkip(_skip.Value);
}
if (_take != null)
{
cursor.SetLimit(_take.Value);
}
if (_indexHint != null)
{
if (_indexHint.IsString)
{
cursor.SetHint(_indexHint.AsString);
}
else if (_indexHint.IsBsonDocument)
{
cursor.SetHint(_indexHint.AsBsonDocument);
}
else
{
throw new NotSupportedException("Index hints must be strings or documents");
}
}
var projection = _projection;
if (_ofType != null)
{
if (projection == null)
{
var paramExpression = Expression.Parameter(DocumentType, "x");
var convertExpression = Expression.Convert(paramExpression, _ofType);
projection = Expression.Lambda(convertExpression, paramExpression);
}
else
{
var paramExpression = Expression.Parameter(DocumentType, "x");
var convertExpression = Expression.Convert(paramExpression, _ofType);
var body = ExpressionParameterReplacer.ReplaceParameter(projection.Body, projection.Parameters[0], convertExpression);
projection = Expression.Lambda(body, paramExpression);
}
}
IProjector projector;
if (projection == null)
{
var projectorType = typeof(IdentityProjector <>).MakeGenericType(DocumentType);
projector = (IProjector)Activator.CreateInstance(projectorType, cursor);
}
else
{
var lambdaType = projection.GetType();
var delegateType = lambdaType.GetGenericArguments()[0];
var sourceType = delegateType.GetGenericArguments()[0];
var resultType = delegateType.GetGenericArguments()[1];
var projectorType = typeof(Projector <,>).MakeGenericType(sourceType, resultType);
var compiledProjection = projection.Compile();
projector = (IProjector)Activator.CreateInstance(projectorType, cursor, compiledProjection);
}
if (_elementSelector != null)
{
return(_elementSelector(projector));
}
else
{
return(projector);
}
}
// public methods
/// <summary>
/// Replaces all occurences of one parameter with a different parameter.
/// </summary>
/// <param name="node">The expression containing the parameter that should be replaced.</param>
/// <param name="fromParameter">The from parameter.</param>
/// <param name="toExpression">The expression that replaces the parameter.</param>
/// <returns>The expression with all occurrences of the parameter replaced.</returns>
public static Expression ReplaceParameter(Expression node, ParameterExpression fromParameter, Expression toExpression)
{
var replacer = new ExpressionParameterReplacer(fromParameter, toExpression);
return replacer.Visit(node);
}