Binding syntax reference
A binding reads a value from the process flow’s data into a field, a token, or a condition. This topic lists the binding forms and the mistakes to avoid. For the two kinds of data a binding reads, see How data moves through a process flow.
Binding forms
| Binding | Reads |
|---|---|
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A value from a specific earlier step’s output, named by its activity identifier. |
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A value from interface data, the global store for the run. |
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The action a person selected on the previous User Task. |
You can drag an input from a node’s Inputs panel into a field, which writes the binding for you.
Expressions
To compare or compute values, use an expression. An expression is wrapped in {= },
and reads a value with ${ }. For example:
{= ${InterfaceData>/candidate/yearsOfExperience} >= 5 }Expressions are used in condition rules. See Condition operators and operand types.
How a condition evaluates
A condition must evaluate to true or false. If it evaluates to anything else, such
as a bare value or a missing field, the path is not taken, and a warning is written to
the logs. Write a condition as a comparison of a bound value against an expected value,
for example {= ${InterfaceData>/name} === "Nora" }, rather than a bare binding
such as {= ${InterfaceData>/name} }.
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A comparison is strict on both value and type. A number matches a number, and text
matches text. |
A few more points hold when you write a condition:
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Single quotes and double quotes both work for text, for example
=== "Nora"and=== 'Nora'. -
Extra spaces inside the expression do not change the result.
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If a path is not taken when you expected it to be, check the logs for a condition-evaluation warning. A misspelled binding or a type mismatch is the usual cause.
Valid and invalid bindings
The following interface data is used for the examples:
{ "contacts": [ { "firstname": "Sofia" }, { "firstname": "Neha" } ] }| Binding | Result |
|---|---|
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Avoid these common mistakes:
| Invalid binding | Reason |
|---|---|
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Reads the previous step’s output, not interface data. |
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Missing the |
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Missing the leading |
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