Parameter Output

Version

Application Scenario

You can use Parameter Assignment to output the results of upstream nodes as parameter values for use by downstream nodes, but some data needs further processing before being output as parameter values.

You want to output data as parameter values directly after processing the data without outputting the processed results to a database and then fetching values from the database as parameter values.

FineDataLink supports direct parameter output using Overview of Data Transformation as shown in the following figure.

Note:

The output parameter can be used by all nodes of downstream branches. It is applicable to scenarios where you need to fetch a great number of parameter values from database tables, APIs, and files for complex calculations.

1. The constraints and usage of parameters output by Parameter Output are the same as those output by Parameter Assignment. For details, see Parameter Assignment.

2 In FineDataLink, parameters can be divided into Task Parameter, Global Parameter, and Built-in Parameter. For details about usage instructions, see Parameter Configuration and Use.

3. For details about the parameter application scenarios in FineDataLink, see Typical Parameter Application in FineDataLink.

Take outputting the processed API data as values of a parameter and using the output parameter to fetch data from a database table to a specified database as an example. The steps are as follows.

• Parse data fetched from the API (https://demo.finedatalink.com/help/book.json in this example) and obtain records with non-null isbn values.

• Output the values of author as a parameter.

• Use the parameter to fetch data meeting conditions from the Book table and output it to the book_out data table.

Outputting a Parameter

Reading API Data

1. Create a scheduled task, drag a Data Transformation node onto the page, and enter the Data Transformation editing page.

2. Drag an API Input operator onto the Data Transformation page and read API data. The API address is https://demo.finedatalink.com/help/book.json. Do not tick Expand Parsed JSON Data into a Two-Dimensional Table to ensure the fetched data is in a JSON format, as shown in the following figure. 

Click Data Preview to view the read JSON data, as shown in the following figure. 

Parsing JSON Data

1. Drag a JSON Parsing operator onto the Data Transformation page and parse the category, author, title, price, and isbn fields. 

Click Data Preview to view the data after parsing, as shown in the following figure. 

Filtering Data

Drag a Data Filter operator onto the Data Transformation page and filter data to get records with non-null isbn values. 

Outputting a Parameter

1. Drag a Parameter Output operator onto the Data Transformation page and output the author field as a parameter. 

Note:

You are advised to set a debug value for the parameter to facilitate previewing results at subsequent nodes that reference this parameter. This debug value does not affect the actual operation.

Click the Back button in the upper right corner.

Configuring Loop Container

1. Since the output parameter mentioned in "Ouputting a Parameter" contain multiple values, you need to use the Loop Container node to pass each parameter value individually into the Data Synchronization node.

Drag a Loop Container node onto the page, and configure the Loop Container node, as shown in the following figure.

2. Drag a Data Synchronization node into the Loop Container node. In the Data Synchronization node, fetch data whose author values are included in values of the author parameter from the Book table, as shown in the following figure. 

Click Data Preview to see the data whose author value is the debug value of the author parameter, as shown in the following figure. 

3. Configure data destination and mapping and select Write Data into Target Table Directly from the drop-down list as Write Method, as shown in the following figure.

Effect Display

Click the Run button in the upper right corner. After the task is successfully executed, the data in book_out is shown in the following figure.