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c#handlebarshelperhandlebars.net

Handlebars.Net If Condition Helper


I try to write a Handlebar.Net helper which works like Equals. The Helper should be used like

{{#eq name "Foo"}}
    true
{{else}}
    false
{{/eq}}

But I don´t know how to implement this helper. In JS there is this example but I can´t find an example for C#.

My first shot was:

Handlebars.RegisterHelper("#eq", (output, context, data) =>
{
    if (data.Length != 2)
        output.WriteSafeString("false");

    output.WriteSafeString(data[0].Equals(data[1]));
});

But this just writes True or False into my file.


Solution

  • I´ve found the solution:

    Handlebars.RegisterHelper(Equals, (output, options, context, data) => 
    {
        if (data.Length != 2)
            options.Inverse(output, null);
    
        if (data[0].Equals(data[1]))
            options.Template(output, null);
        else
            options.Inverse(output, null);
    });
    Handlebars.RegisterHelper(LowerThan, (output, options, context, data) =>
    {
        IntegerOperation(LowerThan, ref output, ref options, ref data);
    });
    
    Handlebars.RegisterHelper(GreaterThan, (output, options, context, data) =>
    {
        IntegerOperation(GreaterThan, ref output, ref options, ref data);
    });
    
    Handlebars.RegisterHelper(LowerEquals, (output, options, context, data) =>
    {
        IntegerOperation(LowerEquals, ref output, ref options, ref data);
    });
    
    Handlebars.RegisterHelper(GreaterEquals, (output, options, context, data) =>
    {
        IntegerOperation(GreaterEquals, ref output, ref options, ref data);
    });
    
    
    private static void IntegerOperation(string operation, ref System.IO.TextWriter output, ref HelperOptions options, ref object[] data)
    {
        if (data.Length != 2)
        {
            options.Inverse(output, null);
            return;
        }
    
        if (!int.TryParse(data[0].ToString(), out int leftValue))
        {
            options.Inverse(output, null);
            return;
        }
    
        if (!int.TryParse(data[1].ToString(), out int rightValue))
        {
            options.Inverse(output, null);
            return;
        }
    
        switch (operation)
        {
            case "lt":
                if (leftValue < rightValue)
                    options.Template(output, null);
                else
                    options.Inverse(output, null);
                break;
            case "le":
                if (leftValue <= rightValue)
                    options.Template(output, null);
                else
                    options.Inverse(output, null);
                break;
            case "gt":
                if (leftValue > rightValue)
                    options.Template(output, null);
                else
                    options.Inverse(output, null);
                break;
            case "ge":
                if (leftValue >= rightValue)
                    options.Template(output, null);
                else
                    options.Inverse(output, null);
                break;
            default:
                break;
        }