Package com.smartgwt.client.docs

Interface TaskIO

public interface TaskIO

Task Input / Output

Input

Tasks require "inputs" to do their work, just like a method call. For example, GridFetchDataTask requires criteria.

For built-in tasks, you can typically use TaskInputExpressions to declare that the inputs of a task are drawn from Process.state, the output of a previous task in the process, or from global context such as ruleScope. See the docs for each task for details.

If you are implementing your own task and want to support TaskInputExpressions for the data required by your task, use +link{task.getExpressionValue(expression)}.

You can also use the property Task.inputs to automatically support TaskInputExpressions: call getInputRecord() to get the values of the provided expressions.

Output

A task can call Task.setOutput() to provide outputs which other tasks can use via TaskInputExpressions or programmatically via APIs such as Process.getLastTaskOutput().

Using the property Task.outputField and/or Task.outputFieldList allows certain properties of the output, from setOutput(), to be written into the Process.state. Use Task.outputField to specify the field in the process state where the task output should be written. Or, for more complex tasks, use Task.outputFieldList to specify multiple fields.

You can also use the property Task.outputExpression to write task output directly into a DataBoundComponent instead of or in addition to the process state.

An output expression is a String prefixed with "$" followed by the DataBoundComponent ID and optionally followed by a dot-separated field name. When no optional field name is specified, the task output is written to the target component using setValues() or setData(). With the optional field name, the task output is written to the target with setFieldValue() or setEditValue(). For a ListGrid the row is either the current edit row or the one selected row.

As an example, consider a DynamicForm with ID of "orderHeader". By specifying an outputExpression as "$orderHeader" for a fetch DSRequestTask the response record will be assigned directly to the DynamicForm.

Inputs examples

inputRecord represents the result of the inputs extracted from the process state.

If the Process.state represented in JSON is: 

  {
     orderId:5,
     orderItems: [
        {name:"Pencils", quantity:3, itemId:2344}
     ],
     orderUser: { name:"Henry Winkle", address:"...", ... }
  }
Consider these input definitions and resulting inputRecord:
  • inputs: "orderId"
    • inputRecord: { orderId: 5 }
  • inputs: [ "orderUser.name", "orderUser" ]
    • inputRecord: { name: "Henry Winkle", orderUser: { name: "Henry Winkle", address: ... }
  • inputs: "orderUser"
    • inputRecord: { name: "Henry Winkle", address: ... }
  • inputs: [ "orderUser" ]
    • inputRecord: { orderUser: { name: "Henry Winkle", address: ... } }
See Also: