Introduction to Dataweave

Introduction to Dataweave: the basics - Dataweave: from scratch #1Watch on YouTube ↗

In this video you’ll see

• What is Dataweave?
• Dataweave Playground
• Anatomy of a Script
• Simple data types
• Operations with simple data
• Data conversion
• Complex data types
• Operations with complex data
• Logical operators
• Working with the payload
• Selectors
• Variables
• Flow control
• Functions
• The Update operation

Tools

Dataweave Playground

Practice exercises

1. Single-value selector

2. Index selector

3. Range selector

4. Multiple selector

5. Descendants selector

6. Attribute selector

7. Create a function

8. Iterate over an Array

9. Filter an Array

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Self-assessment

Answer the following questions to check what you learned:

1. What is a Dataweave script made of?

AIt always has a header and a body.BIt always has a body and, optionally, a header.CIt always has a body; there is no header.

2. Which are the simple data types in Dataweave?

AString, Number and Boolean.BString, Number, Boolean, Date (and its variants) and Period.CString, Number, Boolean, Regex, Null, Date (and its variants) and Period.DString, Number, Boolean, Null, Date (and its variants) and Period.

3. What is the result of adding a '5' (String) and a 5 (Number)?

AThe result is '55' (String), because the values get concatenated and turned into a String.BThe result is '10' (String), because the values get added and turned into a String.CThe result is 55 (Number), because the values get concatenated and turned into a Number.DThe result is 10 (Number), because the values get added and turned into a Number.EThis kind of operation is not possible.

4. Which operator turns a '5' (String) into a Number?

A'5' to NumberB'5' (Number)C'5' as NumberD'5'. It is always cast to a Number automatically.

5. Which are the Complex data types?

AObject and ArrayBObject, Array and NullCObject, Array, Regex, Null, DateDObject, Array and Function

6. What is the correct way to reference the body of the Mule Message in a Script?

AmessageBinputCpayload

7. Which is the single-value selector operator in DataWeave?

A->B=>C.D~>

8. Which of the following selectors returns both the key and the value being queried (that is, returns an object)?

A.*B..C.^D.&E.@

9. Given the input payload [1, 2, 3, 4, 5]. What would the script payload[-3 to -1] (range selector) return?

AThe selection is not possible, since negative indexes cannot be used.B3, 2, 1.C1, 2, 3.D5, 4, 3.E3, 4, 5.Fnull (out of index).

10. Which of the following selectors throws an exception in the script when the key is not present?

A?B.#C!D.@

11. What is the minimum declaration needed to create a variable?

Avar miVariable;Bvar miVariable = 5Cvar miVariable: Number = 5

12. Which of the following statements about the IF is incorrect?

AIFs can be nested (an IF inside another one).BThe ELSE is the branch taken when the IF condition is FALSE.CYou can declare an IF without an ELSE.DYou can declare an ELSE IF so that, when the IF is false, another condition gets checked.

13. Which of the following statements about functions is incorrect?

AFunctions can take functions as parameters.BVariables created inside a function can be reached from the script or from another function.CDeclaring the data type of the parameters a function takes, or the data type it returns, is optional.DVariables defined in the script header can be reached from a function.

Check answers

Result