Skip to content
Docs
flero.ai

Flow control

Flow-control nodes shape the path through your workflow, they don't transform data, they decide what runs next.

If

What: Routes data to a true or false output port based on a condition (or set of conditions combined with AND/OR).

Inputs: Any.

Outputs: true, false. Items that matched the condition leave via true; the rest leave via false.

Configuration:

Field Notes
Conditions A list. Each condition is value1 operator value2.
Combinator and (all must match) or or (at least one).

Operators: equal, notEqual, greaterThan, lessThan, greaterThanOrEqual, lessThanOrEqual, contains, notContains, startsWith, notStartsWith, endsWith, notEndsWith, regex, isEmpty, isNotEmpty, isNull, isNotNull, isTrue, isFalse.

Example: "Is the order amount over $1000?"

value1:   {{ $trigger.body.amount }}
operator: greaterThan
value2:   1000

Connect true to a high-value-order branch; connect false to the normal path.

📸 Screenshot needed: flow-control__if-config.png, If node inspector with one condition configured and both output ports labelled on the canvas.

Switch

What: Multi-way branching. Routes to a named output port based on which case matches.

Inputs: Any.

Outputs: One per case (case1, case2, …, default).

Configuration: A list of cases. Each case has an expression to match plus a label that becomes the output port name. The default port catches anything that didn't match.

Example: "Route by event type."

case1 → eventType == "order.created"   → port: orders
case2 → eventType == "subscription.*"  → port: subscriptions
case3 → eventType == "refund.*"         → port: refunds
default                                → port: default

Loop

What: Iterates over a collection. The downstream chain runs once per item; after the last item, the done port fires.

Inputs: A collection (array, object, range).

Outputs: loop (one item at a time) and done (after all items).

Configuration:

Field Notes
Mode array, object (key/value pairs), range (numeric), batch (groups of N), page (pagination cursors)
Source Expression that resolves to the collection
Batch size For batch and page modes
Filter Optional expression to skip items
Sort Optional field to sort by

Pattern:

[Trigger]──→[List items]──→[Loop]──┐
                                    ├──→[Process one item]──→…
                                    └──→[Loop completes]──→[Summarise]
                                    
                                    (loop port)            (done port)

The downstream node sees $node["Loop"].json as the current item.

📸 Screenshot needed: flow-control__loop-config.png, Loop node inspector in array mode with the source expression pointing to $node["List items"].json.items.

Merge

What: Combines two or more incoming streams into one.

Inputs: Any number, on the single input port (multiple connections allowed).

Outputs: output, items from each input, optionally combined per row.

Configuration:

Field Notes
Mode append (concatenate), merge by index, merge by key (join on a shared field), multiplex (cartesian product)
Key field For merge by key

Use when: Recombining the true and false branches of an If, or joining results from parallel branches.

Delay

What: Pauses the workflow for a fixed (or computed) duration.

Inputs: Any.

Outputs: output, the same data, after the delay.

Configuration:

Field Notes
Duration Milliseconds, or expression returning ms
Strategy fixed or exponential backoff (for retries)

Use when: Rate-limiting yourself against a flaky downstream API; staggering bulk operations; waiting for an external system to catch up.

Approval

What: Pauses execution and awaits a human decision. The workflow status becomes waitingForInput. The approval surfaces in /approvals (and optionally via email / Slack notifications).

Inputs: Data to review.

Outputs: approved and rejected.

Configuration:

Field Notes
Title What the approver sees
Message Long-form description
Data to show Which fields from the upstream node to display
Approvers One or more users / roles
Approval policy Any one, All approvers, Majority
Timeout Optional, what happens if nobody responds in time (reject, approve, escalate)
Public link If on, generates a shareable URL for external approvers (no login required)

See Section 08, Approvals for the full guide.

Error handling

What: Catches a thrown exception from an upstream node so the workflow can continue on a recovery path.

Inputs: Connected to the node you want to protect.

Outputs: output (success path passes through) and error (an exception was caught; error data has message, type, stack, plus original input).

Configuration:

Field Notes
Catch on Which error types to catch (all, timeout, network, authentication, validation, custom regex)
Max retries Retry the protected node N times before routing to error
Retry delay Initial delay; combine with exponential backoff strategy

Chain

What: Sequences dependent operations explicitly, so the runtime treats them as one logical step. Mostly cosmetic, guarantees ordering in the timeline view.

Workflow control

What: Sends control signals (pause, resume, stop) to other workflow runs. Advanced.

Split

What: Splits a single array input into one item per outgoing branch. Like Loop but with parallel branches instead of sequential iteration.

Tips & gotchas

  • If vs Switch: If is binary; Switch supports many cases. For 3+ branches, Switch is cleaner.
  • Loop state is persisted. A workflow can pause mid-loop (e.g. an approval at iteration 47) and resume exactly where it stopped.
  • Merge by key needs a unique key field in every input stream, otherwise rows silently overwrite each other.
  • Delays consume execution time against your workflow timeout. A 10-minute delay on a 5-minute-timeout workflow will fail. Bump the timeout in workflow settings.
  • Error handling doesn't catch every failure mode. Workflow-level failures (invalid expression, missing required field) bypass it. It only catches exceptions thrown during a node's execution.

Found something out of date? This page lives in the Flero docs content set.