API Reference
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    Class Functions

    A class that contains the built-in JMESPath functions.

    The built-in functions are implemented as methods on the Functions class. Each method is decorated with the @Function.signature() decorator to enforce the arity and types of the arguments passed to the function at runtime.

    You can extend the Functions class to add custom functions by creating a new class that extends Functions and adding new methods to it.

    import { search } from '@aws-lambda-powertools/jmespath';
    import { Functions } from '@aws-lambda-powertools/jmespath/functions';

    class MyFunctions extends Functions {
      ⁣@Functions.signature({
        argumentsSpecs: [['number'], ['number']],
        variadic: true,
      })
      public funcMyMethod(args: Array<number>): unknown {
        // ...
      }
    }

    const myFunctions = new MyFunctions();

    search('myMethod(@)', {}, { customFunctions: new MyFunctions() });

    Hierarchy (View Summary)

    Index

    Constructors

    constructor

    Properties

    methods

    Methods

    funcAbs funcAvg funcCeil funcContains funcEndsWith funcFloor funcJoin funcKeys funcLength funcMap funcMax funcMaxBy funcMerge funcMin funcMinBy funcNotNull funcReverse funcSort funcSortBy funcStartsWith funcSum funcToArray funcToNumber funcToString funcType funcValues introspectMethods signature

    Constructors

    Properties

    methods: Set<string> = ...

    A set of all the custom functions available in this and all child classes.

    Methods

    • Get the absolute value of the provided number.

      Parameters

      • args: number

        The number to get the absolute value of

      Returns number

    • Calculate the average of the numbers in the provided array.

      Parameters

      • args: number[]

        The numbers to average

      Returns number

    • Get the ceiling of the provided number.

      Parameters

      • args: number

        The number to get the ceiling of

      Returns number

    • Determine if the given value is contained in the provided array or string.

      Parameters

      • haystack: string

        The array or string to check

      • needle: string

        The value to check for

      Returns boolean

    • Determines if the provided string ends with the provided suffix.

      Parameters

      • str: string

        The string to check

      • suffix: string

        The suffix to check for

      Returns boolean

    • Get the floor of the provided number.

      Parameters

      • args: number

        The number to get the floor of

      Returns number

    • Join the provided array into a single string.

      Parameters

      • separator: string

        The separator to use

      • items: string[]

        The array of itmes to join

      Returns string

    • Get the number of items in the provided item.

      Parameters

      • arg: string | unknown[] | Record<string, unknown>

        The array to get the length of

      Returns number

    • Get the maximum value in the provided array.

      Parameters

      • arg: (string | number)[]

        The array to get the maximum value of

      Returns null | string | number

    • Get the minimum value in the provided array.

      Parameters

      • arg: number[]

        The array to get the minimum value of

      Returns null | string | number

    • Reverses the provided string or array.

      Parameters

      • arg: string | unknown[]

        The string or array to reverse

      Returns string | unknown[]

    • Sort the provided array.

      Parameters

      • arg: string[] | number[]

        The array to sort

      Returns unknown[]

    • Determines if the provided string starts with the provided prefix.

      Parameters

      • str: string

        The string to check

      • prefix: string

        The prefix to check for

      Returns boolean

    • Sum the provided numbers.

      Parameters

      • args: number[]

        The numbers to sum

      Returns number

    • Convert the provided value to a number.

      If the provided value is a number, then it is returned. Otherwise, the value is converted to a number and returned.

      If the value cannot be converted to a number, then null is returned.

      Parameters

      • arg: JSONValue

        The value to convert to a number

      Returns null | number

    • Convert the provided value to a string.

      If the provided value is a string, then it is returned. Otherwise, the value is converted to a string and returned.

      Parameters

      • arg: JSONValue

        The value to convert to a string

      Returns string

    • Lazily introspects the methods of the class instance and all child classes to get the names of the methods that correspond to JMESPath functions.

      This method is used to get the names of the custom functions that are available in the class instance and all child classes. The names of the functions are used to create the custom function map that is passed to the JMESPath search function.

      The method traverses the inheritance chain going from the leaf class to the root class and stops when it reaches the Functions class, which is the root class.

      In doing so, it collects the names of the methods that start with func and adds them to the methods set. Finally, when the recursion collects back to the current instance, it adds the collected methods to the this.methods set so that they can be accessed later.

      Parameters

      • Optionalscope: Functions

        The scope of the class instance to introspect

      Returns Set<string>

    • Decorator to enforce the signature of a function at runtime.

      The signature decorator enforces the arity and types of the arguments passed to a function at runtime. If the arguments do not match the expected arity or types errors are thrown.

      Parameters

      Returns FunctionSignatureDecorator

      import { PowertoolsFunctions } from '@aws-lambda-powertools/jmespath/functions';

      class MyFunctions extends Functions {
        ⁣@Functions.signature({
          argumentsSpecs: [['number'], ['number']],
          variadic: true,
        })
        public funcMyMethod(args: Array<number>): unknown {
          // ...
        }
      }

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