Simple gate and per topic gate using the switch node

README.md

This flow demonstrates how to use a switch to create a gate to block or let messages pass.

Simple gate

The simple gate uses a flow variable, flow.gate that is set using a change node. The switch then checks if flow.gate is true.

Per topic gate

The per topic gate is a single switch that can block or pass messages according to their topic. This is realized using JSONata. Using a change node we will update a flow variable called flow.topicGate that will contain key-value pairs of topic: boolean values. Using the inject node we inject either true or false with the topic we want to let pass or block. In the change node we merge flow.topicGate with a new key:value pair that comes from the inject node: $merge([$flowContext('topicGate'), {topic: payload}]).

The switch node then checks if the following JSONata expression is true by doing a lookup in the flow.topicGate object: $flowContext('topicGate') ~> $lookup(topic) .

flow.json

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