public static AstFilter Translate(TranslationContext context, MethodCallExpression expression)
{
if (AllWithContainsInPredicateMethodToFilterTranslator.CanTranslate(expression, out var arrayFieldExpression, out var arrayConstantExpression))
{
return(AllWithContainsInPredicateMethodToFilterTranslator.Translate(context, arrayFieldExpression, arrayConstantExpression));
}
if (AnyWithContainsInPredicateMethodToFilterTranslator.CanTranslate(expression, out arrayFieldExpression, out arrayConstantExpression))
{
return(AnyWithContainsInPredicateMethodToFilterTranslator.Translate(context, arrayFieldExpression, arrayConstantExpression));
}
var method = expression.Method;
var arguments = expression.Arguments;
if (method.IsOneOf(EnumerableMethod.All, EnumerableMethod.Any, EnumerableMethod.AnyWithPredicate))
{
var sourceExpression = arguments[0];
var(field, filter) = FilteredEnumerableFilterFieldTranslator.Translate(context, sourceExpression);
if (method.IsOneOf(EnumerableMethod.All, EnumerableMethod.AnyWithPredicate))
{
var predicateLambda = (LambdaExpression)arguments[1];
var parameterExpression = predicateLambda.Parameters.Single();
var elementSerializer = ArraySerializerHelper.GetItemSerializer(field.Serializer);
var parameterSymbol = context.CreateSymbol(parameterExpression, "@<elem>", elementSerializer); // @<elem> represents the implied element
var predicateContext = context.WithSingleSymbol(parameterSymbol); // @<elem> is the only symbol visible inside an $elemMatch
var predicateFilter = ExpressionToFilterTranslator.Translate(predicateContext, predicateLambda.Body, exprOk: false);
filter = AstFilter.Combine(filter, predicateFilter);
}
if (method.Is(EnumerableMethod.All))
{
return(AstFilter.Not(AstFilter.ElemMatch(field, AstFilter.Not(filter))));
}
else
{
if (filter == null)
{
return(AstFilter.And(AstFilter.Ne(field, BsonNull.Value), AstFilter.Not(AstFilter.Size(field, 0))));
}
else
{
return(AstFilter.ElemMatch(field, filter));
}
}
}
throw new ExpressionNotSupportedException(expression);
}
public static (AstFilterField, AstFilter) Translate(TranslationContext context, Expression sourceExpression)
{
if (sourceExpression is MethodCallExpression sourceMethodCallExpression)
{
var method = sourceMethodCallExpression.Method;
var arguments = sourceMethodCallExpression.Arguments;
if (method.Is(EnumerableMethod.OfType))
{
var ofTypeSourceExpression = arguments[0];
var(sourceField, sourceFilter) = Translate(context, ofTypeSourceExpression);
var nominalType = ArraySerializerHelper.GetItemSerializer(sourceField.Serializer).ValueType;
var actualType = method.GetGenericArguments()[0];
var discriminatorConvention = BsonSerializer.LookupDiscriminatorConvention(actualType);
var discriminatorField = AstFilter.Field(discriminatorConvention.ElementName, BsonValueSerializer.Instance);
var discriminatorValue = discriminatorConvention.GetDiscriminator(nominalType, actualType);
var ofTypeFilter = AstFilter.Eq(discriminatorField, discriminatorValue);
var actualTypeSerializer = context.KnownSerializersRegistry.GetSerializer(sourceExpression);
var enumerableActualTypeSerializer = IEnumerableSerializer.Create(actualTypeSerializer);
var actualTypeSourceField = AstFilter.Field(sourceField.Path, enumerableActualTypeSerializer);
var combinedFilter = AstFilter.Combine(sourceFilter, ofTypeFilter);
return(actualTypeSourceField, combinedFilter);
}
if (method.Is(EnumerableMethod.Where))
{
var whereSourceExpression = arguments[0];
var(sourceField, sourceFilter) = Translate(context, whereSourceExpression);
var predicateLambda = (LambdaExpression)arguments[1];
var parameterExpression = predicateLambda.Parameters.Single();
var itemSerializer = ArraySerializerHelper.GetItemSerializer(sourceField.Serializer);
var parameterSymbol = context.CreateSymbol(parameterExpression, "@<elem>", itemSerializer); // @<elem> represents the implied element
var predicateContext = context.WithSingleSymbol(parameterSymbol); // @<elem> is the only symbol visible inside an $elemMatch
var whereFilter = ExpressionToFilterTranslator.Translate(predicateContext, predicateLambda.Body, exprOk: false);
var combinedFilter = AstFilter.Combine(sourceFilter, whereFilter);
return(sourceField, combinedFilter);
}
}
var field = ExpressionToFilterFieldTranslator.Translate(context, sourceExpression);
return(field, null);
}
