修改表达式<func<object> &gt; </func<object>

Question

I need to modify a given Expression.

The default Expression will be called like this:

LocalizationService.Current.GetString(() => GeneralResources.Products)

Where GeneralResources.Products is a static string:

public class GeneralResources
{
        public static string Products => "Products";
        public static string ProductsExtra => "Products extra";
}

Now I've added a method to check on a specific something to change the Expression so not GeneralResources.Products will be used but GeneralResources.ProductsExtra

But I don't know how to exactly change this object.

This is what I've so far:

public static string GetString(
    this LocalizationService service,
    Expression<Func<object>> resource,
    params object[] formatArguments)
{
    if (customCheck == true)
    {
        // TODO: Change from GeneralResources.Products (resource) to GeneralResources.ProductsExtra
        
        var translation = service.GetStringByCulture(() => resource + "Extra", CultureInfo.CurrentUICulture, formatArguments);
        if (!string.IsNullOrEmpty(translation)) return translation;
    }

    return service.GetStringByCulture(resource, CultureInfo.CurrentUICulture, formatArguments);
}

Hopefully someone can help me out.

Thanks in advance!

Grtz Sander

Answer 1

Finally fixed it with this code:

public static string GetString(
        this LocalizationService service,
        Expression<Func<object>> resource,
        params object[] formatArguments)
    {
        if (resource == null)
            throw new ArgumentNullException(nameof(resource));

        if (customCheck == true)
        {
            try
            {
                var body = resource.Body as MemberExpression;
                MemberExpression member = Expression.Property(null, body.GetDeclaringType(), body.Member.Name + "Extra");
                resource = Expression.Lambda<Func<object>>(member);

                var translation = service.GetStringByCulture(resource, CultureInfo.CurrentUICulture, formatArguments);
                if (!string.IsNullOrEmpty(translation)) return translation;
            }
            catch
            {
                //ignore exception, means that translation isn't available
            }
        }

        return service.GetStringByCulture(resource, CultureInfo.CurrentUICulture, formatArguments);
    }