Intermediate Recipe: Using a Function Mechanism

[hidayah]

Level: Intermediate
Steps Being Focused on:

• Function Signature
  This step defines the expected parameters and returns from a chain, similar to a function signature in a programming language.

• Function Call
  This step emulates a function call by calling another chain which has a defined Function Signature.

Scenario used as an Example:

• How to retrieve the month from a date string field (e.g., 2022-02-01) in the form of an integer (e.g., 02) by using a Function Mechanism.

Notes:

• Using a function mechanism helps to:
  – Eliminate explicitly naming of fields in every similar usage of a chain call.
  – Accidentally overwriting of any other fields due to temporary logic names in the called chain.

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1. Navigate to the ETL module & create a new ETL chainset.

2. In the chainset, add a new chain.
   For example, “Chain A”

3. Add the step, Function Mechanism with the following inputs as follows:
   *able to specify up to 5 Parameters and Returns each. **![|466x399]
   

   

4. Add the step, String Slice with the following inputs as follows:
   

   

5. Add the step, Change Field Type with the following inputs as follows:
   

   

6. Add the step, Rename Field with the following inputs as follows:
   

   

7. In the same chainset, add another chain.
   For example, “Chain B”

8. As an example, add the following data using the step, JSON Record
   

   

9. Add 2 Function Call steps as shown below:
   In Fields & Out Fields are as per declared in Step 3
   

   
   
   In Fields & Out Fields are as per declared in Step 3
   
   

10. Run Chain B & you should be able to get results as shown below:
    

    

• firstMonth has extracted the Month from the date string, first
• secondMonth has extracted the Month from the date string, second
• unchanged field remains as it is not passed into a function call.

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Overview of Chain A

Overview of Chain B