Single element Matrix generation.

[bigkevmcd]

This allows the Matrix to generate a single element, instead of multiple elements.

[bigkevmcd]

https://github.com/weaveworks/weave-gitops-interlock/issues/472

[foot]

This both

1. wraps all items into a single item
2. disables calculating the cartesian product

Which is a bit different to the apiClient singleElement which only does step 1. I'm not sure if there is a use case for doing singleElement + cartesian product?

    - matrix:
        singleElement: true
        cartesianProduct: true

At the moment I think of the matrix gen as being the cartesian gen, but we could also promote it more as the "combining generators generator".

[bigkevmcd]

Good question, honest answer, I don't have a use-case for this just now, but it doesn't preclude us doing it.

This was implemented to solve a very specific problem, and it's a fairly generic solution for doing it.

See https://github.com/weaveworks/weave-gitops-interlock/issues/472 and #103 :-)

[foot]

Do we need this loop here or can we just

Suggested change

	for rk, existing := range result {
	if generator.name == rk {
	result[rk] = append(existing.([]map[string]any), element)
	}
	}
	result[generator.name] = append(result[generator.name].([]map[string]any), element)

kind of thing?

[bigkevmcd]

we only want to store things for the top-level generators, not all generators are assumed to be named.

if result[generator.name] is nil here, you'll get...

panic: interface conversion: interface {} is nil, not []map[string]interface {} [recovered]
	panic: interface conversion: interface {} is nil, not []map[string]interface {}

[foot]

Gotcha 👍 , yeah, if we guard the name too though would it make sense?

if generator.name == "" {
	unnamed = append(unnamed, element)
} else {
	result[generator.name] = append(result[generator.name].([]map[string]any), element)
}

[foot]

Very cool! ⭐