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fix: v2 null safety #100

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fix: v2 null safety #100

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156b3bc
wip
ArthurFreeb Sep 27, 2025
a62033f
wip
ArthurFreeb Sep 28, 2025
3e4aa54
Merge branch 'feat/v2' into fix/v2/null-safety
ArthurFreeb Sep 29, 2025
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143 changes: 113 additions & 30 deletions src/GoatQuery/src/Evaluator/FilterEvaluator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -52,21 +52,27 @@ private static Result<Expression> EvaluatePropertyPathExpression(
(Expression)context.CurrentLambda.Parameter :
context.RootParameter;

var propertyPathResult = BuildPropertyPath(propertyPath, baseExpression, context.PropertyMappingTree);
if (propertyPathResult.IsFailed) return Result.Fail(propertyPathResult.Errors);
var safePathResult = BuildPropertyPathWithGuard(propertyPath.Segments, baseExpression, context.PropertyMappingTree);
if (safePathResult.IsFailed) return Result.Fail(safePathResult.Errors);

var finalProperty = propertyPathResult.Value;
var (finalProperty, guard, container) = safePathResult.Value;

if (exp.Right is NullLiteral)
{
var nullComparison = CreateNullComparison(exp, finalProperty);
return nullComparison;
return ComposeNestedNullComparison(finalProperty, guard, exp.Operator);
}

var comparisonResult = EvaluateValueComparison(exp, finalProperty);
if (comparisonResult.IsFailed) return comparisonResult;

return comparisonResult.Value;
var comparison = comparisonResult.Value;

var requireFinalNotNull = RequiresFinalNotNull(exp.Operator, finalProperty, exp.Right);
var combinedGuard = requireFinalNotNull
? Expression.AndAlso(guard, Expression.NotEqual(finalProperty, Expression.Constant(null, finalProperty.Type)))
: guard;

return Expression.AndAlso(combinedGuard, comparison);
}

private static Result<MemberExpression> BuildPropertyPath(
Expand All @@ -84,7 +90,6 @@ private static Result<MemberExpression> BuildPropertyPath(

current = Expression.Property(current, propertyNode.ActualPropertyName);

// Navigate to nested mapping for next segment
if (!isLast)
{
if (!propertyNode.HasNestedMapping)
Expand All @@ -97,6 +102,55 @@ private static Result<MemberExpression> BuildPropertyPath(
return Result.Ok((MemberExpression)current);
}

private static Result<(MemberExpression Final, Expression Guard, Expression Container)> BuildPropertyPathWithGuard(
IList<string> segments,
Expression startExpression,
PropertyMappingTree propertyMappingTree)
{
if (segments == null || segments.Count == 0)
return Result.Fail("Property path segments cannot be empty");

var current = startExpression;
var currentMappingTree = propertyMappingTree;

Expression guard = Expression.Constant(true);
Expression container = startExpression;

for (int i = 0; i < segments.Count; i++)
{
var segment = segments[i];
var isLast = i == segments.Count - 1;

if (!currentMappingTree.TryGetProperty(segment, out var propertyNode))
return Result.Fail($"Invalid property '{segment}' in path");

var next = Expression.Property(current, propertyNode.ActualPropertyName);

if (!isLast)
{
if (!propertyNode.HasNestedMapping)
return Result.Fail($"Property '{segment}' does not support nested navigation");

if (!next.Type.IsValueType || Nullable.GetUnderlyingType(next.Type) != null)
{
var notNull = Expression.NotEqual(next, Expression.Constant(null, next.Type));
guard = Expression.AndAlso(guard, notNull);
}

current = next;
container = current;
currentMappingTree = propertyNode.NestedMapping;
}
else
{
var final = Expression.Property(current, propertyNode.ActualPropertyName);
return Result.Ok(((MemberExpression)final, guard, container));
}
}

return Result.Fail("Invalid property path");
}

private static Result<MemberExpression> ResolvePropertyPathForCollection(
PropertyPath propertyPath,
Expression baseExpression,
Expand All @@ -113,8 +167,6 @@ private static Result<MemberExpression> ResolvePropertyPathForCollection(
return Result.Fail($"Invalid property '{segment}' in lambda expression property path");

current = Expression.Property(current, propertyNode.ActualPropertyName);

// Navigate to nested mapping for next segment
if (i < propertyPath.Segments.Count - 1)
{
if (!propertyNode.HasNestedMapping)
Expand Down Expand Up @@ -326,7 +378,6 @@ private static Result<Expression> EvaluateLambdaExpression(QueryLambdaExpression

var (collectionProperty, elementType, lambdaParameter) = setupResult.Value;

// Enter lambda scope
context.EnterLambdaScope(lambdaExp.Parameter, lambdaParameter, elementType);

try
Expand Down Expand Up @@ -382,7 +433,7 @@ private static Result<MemberExpression> ResolveCollectionProperty(QueryExpressio
{
return Result.Fail($"Invalid property '{identifier.TokenLiteral()}' in lambda expression");
}
return Expression.Property(baseExpression, propertyNode.ActualPropertyName);
return Expression.Property(baseExpression, propertyNode.ActualPropertyName) as MemberExpression;

case PropertyPath propertyPath:
return ResolvePropertyPathForCollection(propertyPath, baseExpression, propertyMappingTree);
Expand All @@ -392,6 +443,42 @@ private static Result<MemberExpression> ResolveCollectionProperty(QueryExpressio
}
}

private static bool RequiresFinalNotNull(string operatorKeyword, MemberExpression finalProperty, QueryExpression right)
{
if (operatorKeyword.Equals(Keywords.Contains, StringComparison.OrdinalIgnoreCase))
return true;

if (right is NullLiteral)
return false;

var type = finalProperty.Type;
if (!type.IsValueType)
return true;

return Nullable.GetUnderlyingType(type) != null;
}

private static Expression ComposeNestedNullComparison(MemberExpression finalProperty, Expression guard, string operatorKeyword)
{
var isEq = operatorKeyword.Equals(Keywords.Eq, StringComparison.OrdinalIgnoreCase);
var isNe = operatorKeyword.Equals(Keywords.Ne, StringComparison.OrdinalIgnoreCase);
var nullConst = Expression.Constant(null, finalProperty.Type);
var finalEqNull = Expression.Equal(finalProperty, nullConst);
var finalNeNull = Expression.NotEqual(finalProperty, nullConst);
var notGuard = Expression.Not(guard);

if (isEq)
{
return Expression.OrElse(notGuard, finalEqNull);
}
else if (isNe)
{
return Expression.AndAlso(guard, finalNeNull);
}

return Expression.AndAlso(guard, finalEqNull);
}

private static Result<Expression> EvaluateLambdaBody(QueryExpression expression, FilterEvaluationContext context)
{
return expression switch
Expand Down Expand Up @@ -431,7 +518,6 @@ private static Result<Expression> EvaluateLambdaBodyIdentifier(InfixExpression e

if (identifierName.Equals(context.CurrentLambda.ParameterName, StringComparison.OrdinalIgnoreCase))
{
// For primitive types (string, int, etc.), allow direct comparisons with the lambda parameter
if (IsPrimitiveType(context.CurrentLambda.ElementType))
{
return EvaluateValueComparison(exp, context.CurrentLambda.Parameter);
Expand Down Expand Up @@ -467,28 +553,29 @@ private static Result<Expression> EvaluateLambdaBodyLogicalOperator(InfixExpress

private static Result<Expression> EvaluateLambdaPropertyPath(InfixExpression exp, PropertyPath propertyPath, ParameterExpression lambdaParameter)
{
// Skip the first segment (lambda parameter name) and build property path from lambda parameter
var current = (Expression)lambdaParameter;
var elementType = lambdaParameter.Type;
var mapping = PropertyMappingTreeBuilder.BuildMappingTree(elementType, GetDefaultMaxDepth());

// Build property path from lambda parameter
var pathResult = BuildLambdaPropertyPath(current, propertyPath.Segments.Skip(1).ToList(), elementType);
if (pathResult.IsFailed) return pathResult;

current = pathResult.Value;
var safePathResult = BuildPropertyPathWithGuard(propertyPath.Segments.Skip(1).ToList(), lambdaParameter, mapping);
if (safePathResult.IsFailed) return Result.Fail(safePathResult.Errors);

var finalProperty = (MemberExpression)current;
var (finalProperty, guard, container) = safePathResult.Value;

// Handle null comparisons
if (exp.Right is NullLiteral)
{
return exp.Operator == Keywords.Eq
? Expression.Equal(finalProperty, Expression.Constant(null, finalProperty.Type))
: Expression.NotEqual(finalProperty, Expression.Constant(null, finalProperty.Type));
return ComposeNestedNullComparison(finalProperty, guard, exp.Operator);
}

// Handle value comparisons
return EvaluateValueComparison(exp, finalProperty);
var comparisonResult = EvaluateValueComparison(exp, finalProperty);
if (comparisonResult.IsFailed) return comparisonResult;

var comparison = comparisonResult.Value;
var requireFinalNotNull = RequiresFinalNotNull(exp.Operator, finalProperty, exp.Right);
var combinedGuard = requireFinalNotNull
? Expression.AndAlso(guard, Expression.NotEqual(finalProperty, Expression.Constant(null, finalProperty.Type)))
: guard;

return Expression.AndAlso(combinedGuard, comparison);
}

private static Expression CreateAnyExpression(MemberExpression collection, LambdaExpression lambda, Type elementType)
Expand Down Expand Up @@ -522,7 +609,6 @@ private static Result<Expression> BuildLambdaPropertyPath(Expression startExpres

current = Expression.Property(current, propertyNode.ActualPropertyName);

// Update mapping tree for nested navigation
if (propertyNode.HasNestedMapping)
{
currentMappingTree = propertyNode.NestedMapping;
Expand All @@ -539,7 +625,6 @@ private static int GetDefaultMaxDepth()

private static Type GetCollectionElementType(Type collectionType)
{
// Handle IEnumerable<T>
if (collectionType.IsGenericType)
{
var genericArgs = collectionType.GetGenericArguments();
Expand All @@ -550,7 +635,6 @@ private static Type GetCollectionElementType(Type collectionType)
}
}

// Handle arrays
if (collectionType.IsArray)
{
return collectionType.GetElementType();
Expand All @@ -563,7 +647,6 @@ private static Result<ConstantExpression> GetIntegerExpressionConstant(int value
{
try
{
// Fetch the underlying type if it's nullable.
var underlyingType = Nullable.GetUnderlyingType(targetType);
var type = underlyingType ?? targetType;

Expand Down