File: Read Node

The File: Read Node allows you to read a file from disk in the device’s Gateway Edge Agent. This node is only available in edge workflows.

Configuration

There are five configuration settings for this node:

• File Path: (Required) A string template for the location of the file to read within the container. This must resolve to a path that the agent’s Docker container has permission to read; in most cases this requires mounting a volume into the container.
• Encoding: The file encoding (defaults to UTF-8).
• Start Position: A string template or integer for the byte at which to start reading. Not setting a value defaults to the start of the file. Passing a negative integer will start reading that many bytes from the end of the file.
• Bytes to Read: A string template or integer for the number of bytes to read. Not setting a value reads until the end of the file.
• Result Path: (Required) A payload path for where to store the result of the operation.

Attempting to read a file that is larger than 5MB will result in an error.

Result

In the example above, the workflow will retrieve the contents of the file at the payload path data.fileName. If the result path is set to data.result, and the read operation was successful, your output would look like the following:

{
  "data": {
    "result": {
      "bytesRead": 100,
      "content": "Some kind of file content that is on your edge machine, maybe a log file, maybe a configuration file..."
    }
  }
}

If the read was unsuccessful then the output would look like the following:

{
  "data": {
    "result": {
      "error": {
        "type": "FILE_READ_ERROR",
        "message": "A message describing the reason for the error."
      }
    }
  }
}

Related Nodes

• File: Write Node