Serialize falsy values for Durable Functions #383
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| try { | ||
| if (result) { | ||
| if (result || (isDurableBinding && result != null)) { |
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if isDurableBinding == true the result can be (0, false, undef, '') ? Can you please add a comment describing why it happens for durable but not for regular executions.
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That's correct, in durable bindings such as activityTriggers, the result can be 0, false, and "". This is because Durable Function activities are meant to be abstractions similar to regular function invocations, so the programming model should, in theory, allow for any output value that would be valid to return in regular JavaScript and is JSON serializable. This includes the values: 0, false, and "". This was also a behavior we used to have in the past, but it stopped working recently, as described here: Azure/azure-functions-durable-js#50
I've also expanded my comments in the PR to make this clearer :) Please let me know if there's anything else I can clarify!
As for serializing undefined, I think that gets serialized as null anyways. I can certainly write code to explicitly avoid serializing undefined though. Please let me know if you would prefer I added that.
Replaces: #364
Due to legacy behavior, falsy values ("", false, 0) in JS currently do not get serialized. We cannot patch this behavior without breaking some JS customers, but also leaving this behavior unpatched breaks Durable Functions. In this PR, I try to find a middle-ground by ensuring that falsy values get serialized only when returning to the Durable Functions output binding.