Humanizr/Humanizer · error · InvalidOperationException

Missing required integer property '{member.SourcePath}'.

Error message

Missing required integer property '{member.SourcePath}'.

What it means

Thrown during source generation by GetInt64Value when a number-to-words engine contract declares a required integer member, but the locale YAML neither provides that property as a JSON number at the member's SourcePath nor defines a DefaultValue fallback. The generator cannot emit a valid constructor argument for the converter, so it halts code emission with this message naming the missing SourcePath.

Source

Thrown at src/Humanizer.SourceGenerators/Generators/ProfileCatalogs/NumberToWordsEngineContractFactory.cs:600

            return bool.TryParse(member.DefaultValue, out var defaultValue) && defaultValue;
        }

        static long GetInt64Value(JsonElement root, EngineContractMember member)
        {
            if (EngineContractUtilities.TryGetElement(root, member.SourcePath, out var value) &&
                value.ValueKind == JsonValueKind.Number &&
                value.TryGetInt64(out var number))
            {
                return number;
            }

            if (member.DefaultValue is not null && long.TryParse(member.DefaultValue, NumberStyles.Integer, CultureInfo.InvariantCulture, out number))
            {
                return number;
            }

            throw new InvalidOperationException($"Missing required integer property '{member.SourcePath}'.");
        }

        static long? GetOptionalInt64Value(JsonElement root, EngineContractMember member)
        {
            if (EngineContractUtilities.TryGetElement(root, member.SourcePath, out var value) &&
                value.ValueKind == JsonValueKind.Number &&
                value.TryGetInt64(out var number))
            {
                return number;
            }

            return member.DefaultValue is not null &&
                   long.TryParse(member.DefaultValue, NumberStyles.Integer, CultureInfo.InvariantCulture, out number)
                ? number
                : null;
        }

    }

View on GitHub (pinned to ffc2b77c0f)

Solutions

1. Open the locale YAML file referenced by the build error and add the missing integer property at the path indicated by {member.SourcePath} in the numberToWords block.
2. If the property should be optional, set a DefaultValue on the EngineContractMember in the engine contract definition so the generator has a fallback.
3. Verify the YAML indentation so the integer lands under the correct engine sub-object — a mis-indented scalar can appear as a missing property.
4. Run a clean rebuild (dotnet build) after fixing the YAML to confirm the source generator emits successfully.

Example fix

// locale YAML — before
numberToWords:
  engine: englishStructural
  // missing required integer property 'feminineThreshold'

// after
numberToWords:
  engine: englishStructural
  feminineThreshold: 100

// Before building, validate that every locale YAML numberToWords block
// includes all required integer properties declared by its engine contract.
// Cross-check the engine contract JSON in EngineContractCatalog for
// members with kind 'int32'/'int64' and no defaultValue, then confirm the
// locale YAML has those keys as numeric values.

When it happens

Trigger: Adding or editing a locale YAML under src/Humanizer/Locales whose numberToWords engine is bound to a structural contract (in EngineContractCatalog) that has an int32/int64 member. The locale omits the required integer field (or provides a non-numeric value such as a string or null), and the contract member has no DefaultValue set.

Common situations: A Humanizer maintainer adds a new locale or updates an existing locale's numberToWords block and forgets a required integer property (e.g. a threshold, offset, or mode flag). Also triggered when renaming a property in the engine contract JSON without updating all locale YAML files that use that engine.

Related errors

• Billion-word cardinal strategy requires a singular billion w
• Billion-word cardinal strategy requires a plural billion wor
• Property '{propertyName}' must be a string, array, or mappin
• Property '{propertyName}' must be a mapping.
• Expected JSON array or mapping.

AI-assisted analysis of Humanizr/Humanizer@ffc2b77c0f (2026-08-13). Data as JSON: /api/errors/247d00d8859023e6. Report an issue: GitHub.