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You can also refer to the values of the other fields in Jira expression. You need to embrace the name of the system field or the id of the custom field with double curly brackets. Note that the value will be available only when the execution of the field behaviour is triggered by the on change event of the field referred.
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Defining parameters
You can define parameters which will store the data coming from your external APIs. Then, you can use those parameters in the Jira expressions.
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You can then refer to your parameter in the Jira expression using double curly brackets.
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Parameters depending on data entered in other fields
You can send the values of fields to your external APIs and set the parameter value according to the response. This also requires that the execution of the field behaviour will be triggered by the change of the field whose value will be sent to the API.
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