OrchardCMS/OrchardCore · error · InvalidCastException

Cannot convert to Double

Error message

Cannot convert {value} to Double

What it means

The explicit operator double on JsonDynamicValue converts via GetValue<double>() and throws InvalidCastException when the wrapped value is null or the JSON token cannot be represented as a double. The nullable operator (double?) exists for non-throwing access.

Solutions

1. Ensure the JSON token is a JSON number before casting
2. Use the nullable cast (double?) and handle null
3. Pre-validate with double.TryParse on value.ToString() when the token may be a numeric string
4. Null-check the JsonDynamicValue wrapper before casting

Example fix

// before
var ratio = (double)jsonDynamicValue["Ratio"];
// after
var ratio = (double?)jsonDynamicValue["Ratio"] ?? 0d;

if (jsonDynamicValue is null) throw new InvalidOperationException("null wrapper");
var raw = jsonDynamicValue.ToString();
if (!double.TryParse(raw, NumberStyles.Float, CultureInfo.InvariantCulture, out _))
    throw new InvalidOperationException($"'{raw}' is not a double");
var d = (double)jsonDynamicValue;

static bool TryGetDouble(JsonDynamicValue v, out double value)
{
    value = default;
    if (v is null) return false;
    var d = (double?)v;
    if (d is null) return false;
    value = d.Value;
    return true;
}

double ratio;
try
{
    ratio = (double)jsonDynamicValue["Ratio"];
}
catch (InvalidCastException ex)
{
    ratio = 0d;
}

When it happens

Trigger: Executing `(double)jsonDynamicValue` where the wrapper/_jsonValue is null or the token is a non-numeric string, boolean, object, or array.

Common situations: Numeric measurements in JSON stored as strings or null; dynamic access to content-item or configuration JSON where a field's type drifted; parsing third-party API payloads dynamically.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Cannot convert to DateTime
• Cannot convert to DateTimeOffset
• Cannot convert to Decimal
• Cannot convert to Guid
• Cannot convert to

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/7b49c9ec705ba399. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore.Abstractions/Json/Dynamic/JsonDynamicValue.cs:340

    {
        return value?._jsonValue?.GetValue<DateTimeOffset?>();
    }

    public static explicit operator decimal(JsonDynamicValue value)
    {
        return value?._jsonValue?.GetValue<decimal>()
            ?? throw new InvalidCastException($"Cannot convert {value} to Decimal");
    }

    public static explicit operator decimal?(JsonDynamicValue value)
    {
        return value?._jsonValue?.GetValue<decimal?>();
    }

    public static explicit operator double(JsonDynamicValue value)
    {
        return value?._jsonValue?.GetValue<double>()
            ?? throw new InvalidCastException($"Cannot convert {value} to Double");
    }

    public static explicit operator double?(JsonDynamicValue value)
    {
        return value?._jsonValue?.GetValue<double?>();
    }

    public static explicit operator Guid(JsonDynamicValue value)
    {
        return value?._jsonValue?.GetValue<Guid>()
            ?? throw new InvalidCastException($"Cannot convert {value} to Guid");
    }

    public static explicit operator Guid?(JsonDynamicValue value)
    {
        return value?._jsonValue?.GetValue<Guid?>();
    }

View on GitHub (pinned to 4306c0717f)