Understand Expressions in the SnapLogic Platform
Arithmetic Operators | Description | Example |
---|---|---|
(+, -, *, /) | Similar to the JavaScript arithmetic operators except that increment (++) and decrement (--) are not supported. All arithmetic operators return a floating point number. If an integer is desired, then the global function {{parseInt}} should be used to cast the arithmetic expression as an integer. | 1/2 = .5 parseInt(1/2) = 0 |
Spread Operator | ||
(...) | This operator makes it easier to build arrays, objects, and call functions where the list of arguments is built at runtime. For instance, while using in an array literal, the value on the right of the operator is inserted into the new array at that position. Similarly, in a function call, the array expands and is used as the arguments to the function. In an object literal, the right side of the operator is another object that has its keys added to the new object. | To build a new array that is made up of another array surrounded by two elements: ["header", ...$body, "footer"] To find the maximum value in an array of numbers: Math.max(...$numbers) To create a new object with some fixed values and entries in the "$extra" object: { first_name: $fname, last_name: $lname, ... $extra } |
Special Operators | ||
Conditional (Ternary) (?) | This operator allows you to specify a value to use based on the result of an expression. Syntax:
|
|
instanceof | The Syntax: | $my_array instanceof Array |
The possible values for the type are: Null, Boolean, String, Number, Object, Array, Date, LocalDate, DateTime, and LocalDateTime. | ||
match | This operator allows you to conditionally evaluate one of a number of expressions based on whether an input value matches a given pattern. Learn more about this operator, match Control Flow Operator. | match $score { 90..=100 => 'A', 80..<90 => 'B', 70..<80 => 'C', _ => 'F' } |
typeof | This operator returns the type of a value as a string. The possible return values are: "boolean", "number", "string", "object", and "array". Syntax: | typeof $name (Where $name="SnapLogic") returns "String" |
in | This operator returns true if the property name or array index is in the given object or array. Syntax:
| 'name' in $ |
Comments
You can add notes to your expressions using comments. A comment starts with '/*' and ends with '*/', for example:
The comment is ignored when evaluating the expression—it is only for the reader's benefit.
Operator Precedence
Operator Type | Individual Operators |
---|---|
member | . [] |
call | () |
negation | ! - |
multiply/divide | * / % |
addition/subtraction | + - |
relational | < <= > >= |
equality | == != |
logical-and | && |
logical-or | || |
comma | , |
Unsupported Operations
- Assignment
- Creating variables and assigning values is not supported
- Example: var temp = 10
- Short hand assignment
- Example: count += 5
- Strict equals
- Example: first === last
- Strict not equals
- Example: first !== last
- Increment
- Example: count++
- Decrement
- Example: count--
Accessing Document Values
To access values in a document, you can use JavaScript object accessors.
For a given document data:
Complex Example:
Arrow Functions
You can create custom expression language functions using the arrow function syntax:
// A function that takes multiple parameters: (param1, param2, ..., paramN) => expression // A function that takes a single parameter does not need parentheses: (param) => expression param => expression // A function with no parameters requires parentheses: () => expression // Function parameters can also have default values (param1 = defaultValue1, param2 = defaultValue2, ..., paramN = defaultValueN) => expression
These functions can be passed to other functions that accept callbacks, like Array.map() or Array.filter(), or they can be put into an expression library for use in any expression property in your Pipelines.
Example
To multiply all numbers in an array by ten:
[1, 2, 3].map(x => x * 10)
Result:
[10, 20, 30]
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