Context parameters, in parameter configuration, refer to configuring two special parameters — input parameters and output parameters — to enable automatic data transfer between upstream and downstream nodes.

Usage Restrictions:

• Output parameters: Only SQL, Python, and Shell task nodes support configuring output parameters.
• Transfer level: Only single-level transfer is supported, i.e., only upstream nodes passing to their immediate downstream dependents.
• Transfer size: A maximum of 2MB of data transfer is supported.

Usage Guide

• Upstream Node (Provider): Responsible for generating a value and using it as an output parameter.

  • Configure and Assign Output Parameter: The system captures the query result of the last line of the node's code (e.g., SELECT * from table_A;) and assigns it to a built-in output parameter outputs, then passes the value of this parameter to downstream nodes. The parameter value depends on the code execution result.

• Downstream Node (Consumer): Receives and uses the value provided by the upstream node.

  • Establish Scheduling Dependency: Configure a scheduling dependency on the upstream node.
  • Configure Input Parameter: In the downstream node's parameter configuration area, add an input parameter and set its value source to the upstream node's output parameter.
  • Reference in Code: In the downstream node's code, reference the received value using the ${input_parameter_name} format. For example, if the upstream node passes the value table_A, the downstream code SELECT '${input_parameter_name}'; will print the upstream output result at runtime.

Configuration Instructions

Configure Output Parameters

If you wish to pass the current node's result to downstream, follow these steps:

1. Click the node, then Parameters > Output Parameters
2. Click "New", and the system will automatically fill in the built-in parameter $[output].

Configure Input Parameters

Configure Input Parameters

Open the editing page of the downstream node, click Parameters > Input Parameters, and click New.

Configure the input parameter.

• Parameter Name: The parameter name referenced in the script.

• Parameter Value: Select one of the upstream node's output parameters as the value source for this parameter.

  • Upstream Dependency: From the currently configured upstream tasks, select those that have output parameters as the input parameter value source.
  • Others: To add a task with output parameters from elsewhere, use "Others" to select it. Once selected, the dependency on that task will be automatically configured.

Reference Parameters

In the downstream node's code, reference the parameter using the ${input_parameter_name} format.

Below is an example of referencing the input parameter param in an SQL node:

select "${param}"

If the upstream node passes the assigned result to downstream, the parameter value is typically a two-dimensional array or a comma-separated one-dimensional array. Use the following methods to retrieve values within the array:

• If the upstream is an SQL node (two-dimensional array):

  • Row: ${param[i]}.
  • Cell: ${param[i][j]}.
  • If the upstream is Python/Shell (one-dimensional array): Row: ${param[i]}.