Handle errors

This guide explains how to manage errors that occur when a flow step runs. You can specify whether a failed step requires user action to resolve or if it can be retried.

  • Return an actionable error: Append a button to the error log that directs the user to the step's configuration card, letting them modify their inputs to resolve the error. To mark an error as actionable, return AddOnsResponseService.ErrorActionability.ACTIONABLE. To mark an error as unactionable, return AddOnsResponseService.ErrorActionability.NOT_ACTIONABLE.
  • Retry the step after an error: The flow attempts to run the step again up to 5 times before halting. To mark an error as one that can be retried, return AddOnsResponseService.ErrorRetryability.RETRYABLE. To mark an error that can't be retried, return AddOnsResponseService.ErrorRetryability.NOT_RETRYABLE.

You can also create custom error logs with chips, hyperlinks, and styled text to provide users with more detailed context about the error.

Return an actionable error

The following example builds a step that asks a user for a negative number. If the user enters a positive number, the step returns an actionable error that prompts the user to correct their input.

The following manifest file defines the step's inputs, outputs, and the functions to call for configuration and execution.

JSON

{
  "timeZone": "America/Toronto",
  "dependencies": {},
  "exceptionLogging": "STACKDRIVER",
  "runtimeVersion": "V8",
  "addOns": {
    "common": {
      "name": "Retry Errors Example",
      "logoUrl": "https://www.gstatic.com/images/icons/material/system/1x/pets_black_48dp.png",
      "useLocaleFromApp": true
    },
    "flows": {
      "workflowElements": [
        {
          "id": "returnElementError",
          "state": "ACTIVE",
          "name": "Return Element Error Action",
          "description": "To notify the user that some error has occurred",
          "workflowAction": {
            "inputs": [
              {
                "id": "value1",
                "description": "The input from the user",
                "cardinality": "SINGLE",
                "dataType": {
                  "basicType": "STRING"
                }
              }
            ],
            "outputs": [
              {
                "id": "output_1",
                "description": "The output",
                "cardinality": "SINGLE",
                "dataType": {
                  "basicType": "STRING"
                }
              }
            ],
            "onConfigFunction": "onConfiguration",
            "onExecuteFunction": "onExecution"
          }
        }
      ]
    }
  }
}

The following code builds the configuration card and handles the execution logic, including error handling.

Apps Script

/**
 * Returns a configuration card for the step.
 * This card contains a text input field for the user.
 */
function onConfiguration() {
  let section = CardService.newCardSection()
    .addWidget(CardService.newTextInput()
      .setFieldName("value1")
      .setId("value1")
      .setTitle("Please input negative numbers!"));
  const card = CardService.newCardBuilder().addSection(section).build();
  return card;
}

/**
 * Gets an integer value from variable data, handling both string and integer formats.
 * @param {Object} variableData The variable data object from the event.
 * @return {number} The extracted integer value.
 */
function getIntValue(variableData) {
  if (variableData.stringValues) {
    return parseInt(variableData.stringValues[0]);
  }
  return variableData.integerValues[0];
}

/**
 * Executes the step.
 * If the user input is a positive number, it throws an error and returns an
 * actionable error message. Otherwise, it returns the input as an output variable.
 * @param {Object} e The event object from the workflow.
 */
function onExecution(e) {
  try {
    var input_value = getIntValue(e.workflow.actionInvocation.inputs["value1"]);
    if (input_value > 0) {
      throw new Error('Found invalid positive input value!');
    }

    // If execution is successful, return the output variable and a log.
    const styledText_1 = AddOnsResponseService.newStyledText()
      .setText("Execution completed, the number you entered was: ")
      .addStyle(AddOnsResponseService.TextStyle.ITALIC)
      .addStyle(AddOnsResponseService.TextStyle.UNDERLINE);
    const styledText_2 = AddOnsResponseService.newStyledText().setText(input_value)
      .setFontWeight(AddOnsResponseService.FontWeight.BOLD);

    const workflowAction = AddOnsResponseService.newReturnOutputVariablesAction()
      .setVariables({
        "output_1": AddOnsResponseService.newVariableData().addStringValue(input_value)
      })
      .setLog(AddOnsResponseService.newWorkflowTextFormat()
        .addTextFormatElement(
          AddOnsResponseService.newTextFormatElement().setStyledText(styledText_1)
        ).addTextFormatElement(
          AddOnsResponseService.newTextFormatElement().setStyledText(styledText_2)
        ));

    let hostAppAction = AddOnsResponseService.newHostAppAction().setWorkflowAction(workflowAction);
    return AddOnsResponseService.newRenderActionBuilder().setHostAppAction(hostAppAction).build();

  } catch (err) {
    // If an error occurs, return an actionable error action.
    Logger.log('An error occurred: ' + err.message);

    const workflowAction = AddOnsResponseService.newReturnElementErrorAction()
      // Sets the user-facing error message.
      .setErrorLog(
        AddOnsResponseService.newWorkflowTextFormat()
        .addTextFormatElement(
          AddOnsResponseService.newTextFormatElement().setText("Failed because of invalid input values!"))
      )
      // Makes the error actionable, allowing the user to correct the input.
      .setErrorActionability(AddOnsResponseService.ErrorActionability.ACTIONABLE)
      // Specifies that the error is not automatically retried.
      .setErrorRetryability(AddOnsResponseService.ErrorRetryability.NOT_RETRYABLE);

    let hostAppAction = AddOnsResponseService.newHostAppAction().setWorkflowAction(workflowAction);
    return AddOnsResponseService.newRenderActionBuilder().setHostAppAction(hostAppAction).build();
  }
}

Retry the step after an error

The following example builds a step that simulates a temporary failure. If an error occurs, the step returns an error that can be retried, which causes the flow to rerun the step.

The manifest file defines the step.

JSON

{
  "timeZone": "America/Toronto",
  "dependencies": {},
  "exceptionLogging": "STACKDRIVER",
  "runtimeVersion": "V8",
  "addOns": {
    "common": {
      "name": "Retry Errors Example",
      "logoUrl": "https://www.gstatic.com/images/icons/material/system/1x/pets_black_48dp.png",
      "useLocaleFromApp": true
    },
    "flows": {
      "workflowElements": [
        {
          "id": "retryError",
          "state": "ACTIVE",
          "name": "Retry an error",
          "description": "Simulates a temporary failure and retries the step.",
          "workflowAction": {
            "inputs": [
              {
                "id": "value1",
                "description": "Any input value",
                "cardinality": "SINGLE",
                "dataType": {
                  "basicType": "STRING"
                }
              }
            ],
            "outputs": [
              {
                "id": "output_1",
                "description": "The output",
                "cardinality": "SINGLE",
                "dataType": {
                  "basicType": "STRING"
                }
              }
            ],
            "onConfigFunction": "onRetryConfiguration",
            "onExecuteFunction": "onRetryExecution"
          }
        }
      ]
    }
  }
}

The following code builds the configuration card and handles the retry logic.

Apps Script

/**
 * Returns a configuration card for the step.
 * This card contains a text input field for the user.
 */
function onRetryConfiguration() {
  let section = CardService.newCardSection()
    .addWidget(CardService.newTextInput()
      .setFieldName("value1")
      .setId("value1")
      .setTitle("Enter any value"));
  const card = CardService.newCardBuilder().addSection(section).build();
  return card;
}

/**
 * Executes the step and simulates a transient error.
 * This function fails 80% of the time. When it fails, it returns an
 * error that can be retried.
 * @param {Object} e The event object from the workflow.
 */
function onRetryExecution(e) {
  try {
    // Simulate a transient error that fails 80% of the time.
    if (Math.random() < 0.8) {
      throw new Error('Simulated transient failure!');
    }

    // If execution is successful, return the output variable and a log.
    var input_value = e.workflow.actionInvocation.inputs["value1"].stringValues[0];
    const styledText = AddOnsResponseService.newStyledText()
      .setText(`Execution succeeded for input: ${input_value}`);

    const workflowAction = AddOnsResponseService.newReturnOutputVariablesAction()
      .setVariables({
        "output_1": AddOnsResponseService.newVariableData().addStringValue(input_value)
      })
      .setLog(AddOnsResponseService.newWorkflowTextFormat()
        .addTextFormatElement(
          AddOnsResponseService.newTextFormatElement().setStyledText(styledText)
        ));

    let hostAppAction = AddOnsResponseService.newHostAppAction().setWorkflowAction(workflowAction);
    return AddOnsResponseService.newRenderActionBuilder().setHostAppAction(hostAppAction).build();

  } catch (err) {
    // If a transient error occurs, return an error message saying the step tries to run again.
    Logger.log('A error occurred, trying to run the step again: ' + err.message);

    const workflowAction = AddOnsResponseService.newReturnElementErrorAction()
      // Sets the user-facing error message.
      .setErrorLog(
        AddOnsResponseService.newWorkflowTextFormat()
        .addTextFormatElement(
          AddOnsResponseService.newTextFormatElement().setText("A temporary error occurred. The step will be retried."))
      )
      // Makes the error not actionable by the user.
      .setErrorActionability(AddOnsResponseService.ErrorActionability.NOT_ACTIONABLE)
      // Specifies that the error is automatically retried.
      .setErrorRetryability(AddOnsResponseService.ErrorRetryability.RETRYABLE);

    let hostAppAction = AddOnsResponseService.newHostAppAction().setWorkflowAction(workflowAction);
    return AddOnsResponseService.newRenderActionBuilder().setHostAppAction(hostAppAction).build();
  }
}