Built in functions

This page lists all the existing Function implementations we ship with the app.

How to use this document...

Each function does one simple thing, generate an output vale by applying the function to an input value. To implement this, we can use some configuration parameters affecting the function behavior. These parameters are listed under the configuration map of that belongs to the function under the params object defined for the rule which will use the function during the transformation.

Each function has a version when it was added to the app, a class implementing them, a name they are registered with, an input type, an output type, a parameter list defining how they can be configured, a description stating what they are supposed to do, and we will show an example configuration as well.

Function implementations

Change case

Name: changeCase

Class: ChangeCaseFunction

Since version: 1.1.0

Input type: String

Output type: String

Parameters

Name	Type	Description
to	CaseChange	Defines what is the desired case change operation we want to do.

Description

This function takes the input value and changes the case as defined by the "to" parameter.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "add"
        path: "$.accounts[*]"
        params:
          key: # this is the node defining the first supplier
            name: "staticString"
            value: "address"
          value: # this is the node defining the converting supplier
            name: "converting"
            stringSource: # this supplier would return a lowercase value
              name: "staticString"
              value: "missing"
            converter: # then this function will turn it into Capital
              name: "changeCase"
              to: "CAPITALIZED"

On this input

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe"
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

Produces this output

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe",
      "address": "Missing"
    },
    {
      "id": 2,
      "name": "Jane Doe",
      "address": "Missing"
    }
  ]
}

This example shows that the inserted "Missing" value is capitalized with this function.

Clone key function

Name: cloneKey

Class: CloneKeyFunction

Since version: 1.1.0

Input type: Map < String , Object >

Output type: Map < String , Object >

Parameters

Name	Type	Description
from	String	The name of the key we need to duplicate.
to	String	The name of the destination key.

Description

This function takes the input value as a Map and puts the value assigned to the "from" key using the "to" key.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "replaceMap"
        path: "$.accounts[*]"
        params:
          predicate:
            name: "containsKey"
            key: "billingAddress"
          mapFunction:
            name: "cloneKey"
            from: "billingAddress"
            to: "shippingAddress"

On this input

{
  "accounts": [
    {
      "billingAddress": "123 Main street, SomeCity",
      "id": 1,
      "name": "John Doe"
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

Produces this output

{
  "accounts": [
    {
      "billingAddress": "123 Main street, SomeCity",
      "id": 1,
      "name": "John Doe",
      "shippingAddress": "123 Main street, SomeCity"
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

This example clones "billingAddress" to "shippingAddress" thanks to this function.

Decimal add function

Name: add

Class: DecimalAddFunction

Since version: 1.1.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
operand	BigDecimal	Second operand of the calculation.
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function adds the value provided as "operand" to the input value then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.posts[*].views"
        params:
          predicate: # this is the node defining the predicate
            name: "notNull"
          numberFunction: # this is the node defining the numerical calculation
            name: "add"
            operand: 1
            scale: 0

On this input

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 30,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

Produces this output

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 30,
      "views": 21
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 6
    }
  ]
}

In this example we have increased the number of views using this function.

Absolute value function

Name: absoluteValue

Class: AbsoluteValueFunction

Since version: 1.4.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function replaces the input value with it's absolute value, then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.pointPairs[*].distance"
        params:
          predicate: # this is the node defining the predicate
            name: "notNull"
          numberFunction: # this is the node defining the numerical calculation
            name: "absoluteValue"
            scale: 1

On this input

{
  "pointPairs": [
    {
      "distance": -6.5,
      "point_1": 10,
      "point_2": 3.5
    },
    {
      "distance": 5.90,
      "point_1": "10.00",
      "point_2": "15.91"
    }
  ]
}

Produces this output

{
  "pointPairs": [
    {
      "distance": 6.5,
      "point_1": 10,
      "point_2": 3.5
    },
    {
      "distance": 5.9,
      "point_1": "10.00",
      "point_2": "15.91"
    }
  ]
}

In this example we have replaced the distance values with their absolute values.

Decimal divide function

Name: divide

Class: DecimalDivideFunction

Since version: 1.1.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
operand	BigDecimal	Second operand of the calculation.
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function divides the input value with the value provided as "operand", then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.posts[*].likes"
        params:
          predicate: # this is the node defining the predicate
            name: "notNull"
          numberFunction: # this is the node defining the numerical calculation
            name: "divide"
            operand: 5
            scale: 1

On this input

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 30,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

Produces this output

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 6.0,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0.0,
      "views": 5
    }
  ]
}

In this example we have divided the number of likes by 5.

Decimal dividend function

Name: dividend

Class: DecimalDividendFunction

Since version: 1.4.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
operand	BigDecimal	First operand of the calculation.
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function divides the value provided as "operand" with the input value, then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.posts[0].likes"
        params:
          predicate: # this is the node defining the predicate
            name: "notNull"
          numberFunction: # this is the node defining the numerical calculation
            name: "dividend"
            operand: 600
            scale: 2

On this input

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 30,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

Produces this output

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 20.00,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

In this example we have divided 600 by the number of likes.

Decimal multiply function

Name: multiply

Class: DecimalMultiplyFunction

Since version: 1.1.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
operand	BigDecimal	Second operand of the calculation.
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function multiplies the input value with the value provided as "operand", then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.posts[*].likes"
        params:
          predicate: # this is the node defining the predicate
            name: "notNull"
          numberFunction: # this is the node defining the numerical calculation
            name: "multiply"
            operand: 2
            scale: 0

On this input

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 30,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

Produces this output

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 60,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

In this example we have doubled the number of likes using this function.

Decimal subtract function

Name: subtract

Class: DecimalSubtractFunction

Since version: 1.1.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
operand	BigDecimal	Second operand of the calculation.
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function subtracts the value provided as "operand" from the input value then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.posts[*].likes"
        params:
          predicate: # this is the node defining the predicate
            name: "SpEL"
            expression: "(#root instanceof T(java.math.BigDecimal)) && #root.longValue() > 3"
          numberFunction: # this is the node defining the numerical calculation
            name: "subtract"
            operand: 3
            scale: 0

On this input

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 30,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

Produces this output

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 27,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

In this example we have decreased the number of likes by 3 using this function.

Decimal subtract from function

Name: subtractFrom

Class: DecimalSubtractFromFunction

Since version: 1.4.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
operand	BigDecimal	First operand of the calculation.
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function subtracts input value from the value provided as "operand" then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.posts[*].likes"
        params:
          predicate: # this is the node defining the predicate
            name: "SpEL"
            expression: "(#root instanceof T(java.math.BigDecimal)) && #root.longValue() > 0"
          numberFunction: # this is the node defining the numerical calculation
            name: "subtractFrom"
            operand: 100
            scale: 0

On this input

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 30,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

Produces this output

{
  "posts": [
    {
      "id": 1,
      "title": "Post title 1",
      "likes": 70,
      "views": 20
    },
    {
      "id": 2,
      "title": "Post title 2",
      "likes": 0,
      "views": 5
    }
  ]
}

In this example we subtracted the previous value from 100 using this function.

Round decimal function

Name: roundDecimal

Class: RoundDecimalFunction

Since version: 1.4.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
scale	Integer	The number of digits we want to keep right of the decimal point.

Description

This function parses the input value, then adjusts the "scale" as defined.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.pointPairs[*].*"
        params:
          predicate: # this is the node defining the predicate
            name: "notNull"
          numberFunction: # this is the node defining the numerical calculation
            name: "roundDecimal"
            scale: 0

On this input

{
  "pointPairs": [
    {
      "distance": -6.5,
      "point_1": 10,
      "point_2": 3.5
    },
    {
      "distance": 5.90,
      "point_1": "10.00",
      "point_2": "15.91"
    }
  ]
}

Produces this output

{
  "pointPairs": [
    {
      "distance": -7,
      "point_1": 10,
      "point_2": 4
    },
    {
      "distance": 6,
      "point_1": 10,
      "point_2": 16
    }
  ]
}

In this example we have replaced all numbers with their rounded values.

Epoch millis date add function

Name: epochMillisDateAdd

Class: EpochMilliDateAddFunction

Since version: 1.1.0

Input type: BigDecimal

Output type: BigDecimal

Parameters

Name	Type	Description
amount	Integer	The amount of time units we need to add to the date time.
unit	ChronoUnit	The time unit we want to use to interpret the amount.

Description

This function parses the input value as a date time using the assumption that the number is representing an instant using the epoch millis approach, then adds the necessary "amount" of time "unit"s before converting it back the same way.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "calculate"
        path: "$.accounts..expiresOn"
        params:
          numberFunction: # this is the node defining our function
            name: "epochMillisDateAdd"
            amount: 1
            unit: "HOURS"
          predicate: # we want to match anything
            name: "notNull"

On this input

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe",
      "expiresOn": 1594405286000
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

Produces this output

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe",
      "expiresOn": 1594408886000
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

In this example we have changed the expiration date of an account by adding 1 hour.

HTTP resource by URI function

Name: httpResourceByUri

Class: HttpResourceContentFunction

Since version: 1.2.0

Input type: String

Output type: String

Parameters

Name	Type	Description
uriFunction	Function < String , String >	The function that is calculating the request URI based on the input map.
uri	String	The default request URI as a fallback.
httpMethod	HttpMethod	The default request method as a fallback. Defaults to GET.
httpHeaders	Map < String , String >	The default request headers as a fallback.
charset	Charset	The charset used to read the response. Defaults to UTF-8.

Description

This function is providing a highly flexible HTTP download opportunity. It can operate in with only providing the bare minimum of some base values (an URI, a HTTP method, some headers if needed) as well as it offers the opportunity to use a function to find the URI based on the JSON/Supplier. provided values.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules: # this is where our rule is defined
      - name: "add"
        path: "$"
        params:
          key: # we will add the content under the example node
            name: "staticString"
            value: "example"
          value:
            name: "converting"
            stringSource:
              name: "staticString" # this is the supplier defining what to download
              value: "example.json"
            converter: # this converter changes the supplied value to have the full URI
              name: "httpResourceByUri"
              uriFunction:
                name: "regex"
                pattern: (?<value>.+)
                replacement: "https://raw.githubusercontent.com/nagyesta/yippee-ki-json/main/src/test/resources/json/${value}"

On this input

{
  "uri": "example.json",
  "method": "GET"
}

Produces this output

{
  "uri": "example.json",
  "method": "GET",
  "example": "{\n  \"accounts\": [\n    {\n      \"id\": 1,\n      \"name\": \"John Doe\",\n      \"email\": \"[email protected]\"\n    },\n    {\n      \"id\": 2,\n      \"name\": \"Peter Parker\",\n      \"email\": \"[email protected]\"\n    },\n    {\n      \"id\": 3,\n      \"name\": \"Jane Doe\",\n      \"email\": \"[email protected]\"\n    },\n    {\n      \"id\": 4,\n      \"name\": \"John Smith\",\n      \"email\": \"[email protected]\"\n    }\n  ]\n}"
}

In this example we have used a supplier to provide input.

HTTP resource content map function

Name: httpResource

Class: HttpResourceContentMapFunction

Since version: 1.2.0

Input type: Map < String , Object >

Output type: String

Parameters

Name	Type	Description
uriFunction	Function < Map < String , Object > , String >	The function that is calculating the request URI based on the input map.
methodFunction	Function < Map < String , Object > , String >	The function that is calculating the request method based on the input map.
headerFunction	Function < Map < String , Object > , Map < String , String > >	The function that is calculating the request headers based on the input map.
uri	String	The default request URI as a fallback.
httpMethod	HttpMethod	The default request method as a fallback. Defaults to GET.
httpHeaders	Map < String , String >	The default request headers as a fallback.
charset	Charset	The charset used to read the response. Defaults to UTF-8.

Description

This function allows fully dynamic calculation of all component of the HTTP request while it let's us define fallback values in case overrides are not possible or not desired for any aspects.

This function offers more flexibility than what the rest of the components could fully utilize. Please expect more updates unleashing the full potential of this component.

JSON parse function

Name: jsonParse

Class: JsonParseFunction

Since version: 1.2.0

Input type: String

Output type: Object

Parameters: < NONE >

Description

This function parses the input JSON String and returns an object.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "add"
        path: "$.accounts[*]"
        params:
          key: # this is the node defining the first supplier
            name: "staticString"
            value: "address"
          value: # this is the node defining the second supplier
            name: "converting"
            stringSource: # we are starting with a static string
              name: "staticString"
              value: '{"home":"123 Main street, SomeCity"}'
            converter: # then we are parsing it as JSON
              name: "jsonParse"

On this input

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe"
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

Produces this output

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe",
      "address": {
        "home": "123 Main street, SomeCity"
      }
    },
    {
      "id": 2,
      "name": "Jane Doe",
      "address": {
        "home": "123 Main street, SomeCity"
      }
    }
  ]
}

In this example we have parsed the string and inserted an object instead.

Literal replace function

Name: replace

Class: LiteralReplaceFunction

Since version: 1.1.0

Input type: String

Output type: String

Parameters

Name	Type	Description
find	String	A literal we need to find in the input String.
replace	String	The replacement we need to use.

Description

This function takes the input value, attempts to replace all occurrences of the "find" value with the "replace" value.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "replace"
        path: "$.accounts..lastName"
        params:
          stringFunction: # this is where we define our regex based replace
            name: "regex"
            pattern: (?<firstName>[A-Za-z\-]+) (?<lastName>[A-Za-z\-]+)
            replacement: "${lastName}"
          predicate: # doing it for all Strings
            name: "anyString"
      - name: "replace"
        path: "$.accounts..firstName"
        params:
          stringFunction: # this is where we define our literal based replace
            name: "replace"
            find: " Doe"
            replace: ""
          predicate: # we will do it only for non-null values
            name: "notNull"

On this input

{
  "accounts": [
    {
      "accountId": 1,
      "firstName": "John Doe",
      "lastName": "John Doe"
    },
    {
      "accountId": 2,
      "firstName": "Jane Doe",
      "lastName": "Jane Doe"
    }
  ]
}

Produces this output

{
  "accounts": [
    {
      "accountId": 1,
      "firstName": "John",
      "lastName": "Doe"
    },
    {
      "accountId": 2,
      "firstName": "Jane",
      "lastName": "Doe"
    }
  ]
}

In this example, our replace function removed the " Doe" part from both "firstName" fields.

RegEx replace function

Name: regex

Class: RegexReplaceFunction

Since version: 1.0.0

Input type: String

Output type: String

Parameters

Name	Type	Description
pattern	String	A regex pattern that will be matched against the input, capturing certain named groups for later use.
replacement	String	Defines how the captured groups should be used to piece together the output value using EL-like syntax.

Description

This function takes the input value, attempts to match the pre-defined pattern and capture the values of the named capturing groups. Then using the replacement format it tries to resolve all EL-like placeholders using the captured values form the previous step and returns the result.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "replace"
        path: "$.accounts..lastName"
        params:
          stringFunction: # this is where we define our regex based replace
            name: "regex"
            pattern: (?<firstName>[A-Za-z\-]+) (?<lastName>[A-Za-z\-]+)
            replacement: "${lastName}"
          predicate: # doing it for all Strings
            name: "anyString"
      - name: "replace"
        path: "$.accounts..firstName"
        params:
          stringFunction: # this is where we define our literal based replace
            name: "replace"
            find: " Doe"
            replace: ""
          predicate: # we will do it only for non-null values
            name: "notNull"

On this input

{
  "accounts": [
    {
      "accountId": 1,
      "firstName": "John Doe",
      "lastName": "John Doe"
    },
    {
      "accountId": 2,
      "firstName": "Jane Doe",
      "lastName": "Jane Doe"
    }
  ]
}

Produces this output

{
  "accounts": [
    {
      "accountId": 1,
      "firstName": "John",
      "lastName": "Doe"
    },
    {
      "accountId": 2,
      "firstName": "Jane",
      "lastName": "Doe"
    }
  ]
}

In this example, our regex replace function matches against two "words" using only letters and dashes, separated by a single space. The replacement format tells the function to keep only the second word and throw away the first. We applied this to both "lastName" fields.

String date add function

Name: stringDateAdd

Class: StringDateAddFunction

Since version: 1.1.0

Input type: String

Output type: String

Parameters

Name	Type	Description
formatter	String	The format String we need to use for date time parsing. See
amount	Integer	The amount of time units we need to add to the date time.
unit	ChronoUnit	The time unit we want to use to interpret the amount.

Description

This function parses the input value using the "formatter" pattern, then adds the necessary "amount" of time "unit"s before formatting it using the same pattern.

Example configuration

Applying this configuration

actions:
  - name: "demo"
    rules:
      - name: "replace"
        path: "$.accounts..expiresOn"
        params:
          stringFunction: # this is the node defining our function
            name: "stringDateAdd"
            formatter: "yyyy-MM-dd"
            amount: 6
            unit: "MONTHS"
          predicate: # we want to match any String
            name: "anyString"

On this input

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe",
      "expiresOn": "2020-03-14"
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

Produces this output

{
  "accounts": [
    {
      "id": 1,
      "name": "John Doe",
      "expiresOn": "2020-09-14"
    },
    {
      "id": 2,
      "name": "Jane Doe"
    }
  ]
}

In this example we have changed the expiration date of an account by adding 6 months.