IndexOutOfRangeException in HandlebarsDotNet.PathStructure.PathResolver.ResolvePath for nested object path block expression

[swijnands]

Describe the bug

Trying to enumerate an array via a nested object path:

{{#bundles.styles.vendor}}{{this}}{{/bundles.styles.vendor}}

Results in an IndexOutOfRangeException exception.

Expected behavior:

I would expect the same result as when not using a nested path, i.e.

{{#arr}}....{/arr}}

Or, alternatively, if this is not supported: a clearer exception message.

Test to reproduce

var context = new
{
  bundles = new
  {
	  styles = new
	  {
		  vendor = new[] { "a", "b", "c" }
	  }
  },
  arr = new[] { "d", "e", "f"}
};

// Works: Output = "abc"
Handlebars.Compile("{{#each bundles.styles.vendor}}{{this}}{{/each}}")(context).Dump();

// Works: Output = "def"
Handlebars.Compile("{{#arr}}{{this}}{{/arr}}")(context).Dump();

// Fails: IndexOutOfRangeException in HandlebarsDotNet.PathStructure.PathResolver.ResolvePath
// On line #36: if (!TryResolveValue(pathInfo.IsVariable, context, pathChain[0], instance, out instance))
Handlebars.Compile("{{#bundles.styles.vendor}}{{this}}{{/bundles.styles.vendor}}")(context).Dump();```

[oformaniuk]

This should definitely be supported.
Looks like something weird is happening when we're trying to resolve an actual array to enumerate on.

[sushantduggal]

Facing the same issue, is there a resolution on this?

[devzaak]

I am not 100% sure but this could be a fix for issue:
In: PathResolver.cs
replacing

            var segments = pathInfo.Segments;

with

            var segments = pathInfo.Segments.Where(segment => segment.IsNotEmpty).ToArray();

I am unsure if this will cause other problems though as I am not familiar with lib yet.

[oformaniuk]

@aslezak , it's hard to tell without testing. I'd really appreciate if you can have a look closer.

nit: Try to avoid Linq as this is performance critical path. In this case the check can be placed inside of for that is right below the line you mentioned.

[devzaak]

Will do as soon as I have some spare time, and yes, I noticed I can do continue; in the loop instead of prefiltering them.

[abraham-fox]

No updates for 5 month - I assume I can grab this :) and it seems I've found a simple solution for the issue. @zjklee please take a look at #488.