OrchardCMS/OrchardCore · error · NotImplementedException

Comparing to is currently not implemented.

Error message

Comparing {objA?.GetType()} to {objB?.GetType()} is currently not implemented.

What it means

This NotImplementedException is thrown by JsonDynamicValue.Compare (used by CompareTo and sorting) when both objects are not one of the supported type combinations (numbers, strings, booleans, etc.). The switch default means the pair of runtime types has no comparison rule implemented.

Solutions

Normalize/sort values in your own code by converting to string or number first
Filter out non-comparable (object/array/null) values before sorting
Only compare values of the same JSON kind (numbers with numbers, strings with strings)
Extend wrapping logic to project mixed values to a common type

Example fix

// before
array.OrderBy(x => x.OrderByField) // mixed kinds throw
// after
array.OrderBy(x => x.OrderByField?.GetObjectValue()?.ToString(), StringComparer.Ordinal)

Defensive patterns

Strategy: type-guard

Validate before calling

static bool IsSortable(object? v) => v is not null &&
    v.GetPropertyValue() is JsonElement el &&
    el.ValueKind is JsonValueKind.Number or JsonValueKind.String;

Type guard

static bool IsComparableKind(JsonDynamicValue? v) =>
    v?.GetObjectValue() is JsonElement el &&
    el.ValueKind is JsonValueKind.Number or JsonValueKind.String;

Try / catch

int cmp;
try { cmp = a.CompareTo(b); }
catch (NotImplementedException ex) { /* log, fallback to string compare */
    cmp = string.CompareOrdinal(a?.ToString(), b?.ToString()); }

Prevention

Only sort/order JSON values of the same kind (all numbers or all strings)
Filter out objects/arrays/null before ordering
Project mixed-type fields to a normalized string or double in your own code
Write tests covering the actual field-type distribution of your data

When it happens

Trigger: Calling CompareTo or sorting/ordering JsonDynamicValue instances whose underlying values are of an unsupported type combination, e.g. comparing an object or array to anything, or a boolean to a string.

Common situations: Sorting mixed-type JSON arrays (e.g. JArray with [1, "a", true]); ordering search results where a field varies in type across documents; comparing nested JSON objects for ordering.

Related errors

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/437c16f1f681946c. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore.Abstractions/Json/Dynamic/JsonDynamicValue.cs:737

                    var d1 = Convert.ToDouble(objA, CultureInfo.InvariantCulture);
                    var d2 = Convert.ToDouble(objB, CultureInfo.InvariantCulture);

                    return d1.CompareTo(d2);
                }
                else
                {
                    return Convert.ToInt64(objA, CultureInfo.InvariantCulture).CompareTo(Convert.ToInt64(objB, CultureInfo.InvariantCulture));
                }

            case JsonValueKind.String:

                var s1 = Convert.ToString(objA, CultureInfo.InvariantCulture);
                var s2 = Convert.ToString(objB, CultureInfo.InvariantCulture);

                return string.CompareOrdinal(s1, s2);

            default:
                throw new NotImplementedException($"Comparing {objA?.GetType()} to {objB?.GetType()} is currently not implemented.");
        }
    }

    private static int CompareBigInteger(BigInteger i1, object i2)
    {
        var result = i1.CompareTo(ToBigInteger(i2));

        if (result != 0)
        {
            return result;
        }

        // Converting a fractional number to a BigInteger will lose the fraction
        // check for fraction if result is two numbers are equal
        if (i2 is decimal d1)
        {
            return (0m).CompareTo(Math.Abs(d1 - Math.Truncate(d1)));
        }

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