Power Automate (WDL) cheat sheet

Power Automate expressions are Workflow Definition Language (WDL), not Power Fx. The functions, the syntax, and the case rules are different — wdl function names are camelCase and quotes are single quotes. Everything below is a genuine WDL expression you can drop into the expression editor.

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Referencing data

Most flow logic is plumbing values between actions. These functions pull values out of triggers, actions, variables, and loop items.

triggerBody

The body of the trigger

triggerBody()?['Email']

→ A trigger field

The ?[ ] syntax is null-safe — it returns null instead of failing when the field is missing.

triggerOutputs

Full outputs of the trigger

triggerOutputs()?['headers']

→ Trigger output

outputs

Outputs of a named action

outputs('Compose')

→ Action output

body

Body of a named action

body('Get_item')?['Title']

→ Action body field

item

Current item in Apply to each

item()?['ID']

→ Loop item field

items

Item of a named loop

items('Apply_to_each')?['Status']

→ Loop item field

Use items() with the loop name when you nest loops, so you can target a specific one.

variables

Read a flow variable

variables('counter')

→ Variable value

parameters

Read an environment parameter

parameters('ApiBaseUrl')

→ Parameter value

Strings

concat

Join strings together

concat('PO-', variables('id'))

→ "PO-1042"

substring

Slice by position and length

substring('PowerStack', 5, 5)

→ "Stack"

replace

Replace all occurrences

replace('a-b-c', '-', '/')

→ "a/b/c"

toUpper / toLower

Change case

toUpper('po-12')

→ "PO-12"

trim

Remove leading/trailing spaces

trim(' hi ')

→ "hi"

length

Count characters (or array items)

length('PowerStack')

→ 10

indexOf

Position of a substring

indexOf('a@b.com', '@')

→ 1

startsWith / endsWith

Test a prefix or suffix

startsWith(item()?['Name'], 'PO-')

→ true / false

split

Break a string into an array

split('a,b,c', ',')

→ ["a","b","c"]

guid

Generate a new GUID

guid()

→ A unique id

formatNumber

Format a number as a string

formatNumber(1234.5, 'C2', 'en-GB')

→ "£1,234.50"

Arrays & collections

first / last

First or last array element

first(body('Get_items')?['value'])

→ One item

length

Count items in an array

length(variables('rows'))

→ A number

contains

Test for membership

contains(variables('ids'), 7)

→ true / false

empty

Test for an empty array/string/object

empty(body('Get_items')?['value'])

→ true / false

The cleanest way to branch on a no-results query.

join

Join an array into a string

join(variables('tags'), ', ')

→ "x, y, z"

take / skip

Slice from the start / past the start

take(variables('rows'), 10)

→ First 10

union

Merge arrays, dropping duplicates

union(variables('a'), variables('b'))

→ Combined array

intersection

Items present in both arrays

intersection(variables('a'), variables('b'))

→ Common items

createArray

Build an array from values

createArray('a', 'b', 'c')

→ ["a","b","c"]

range

Sequence of integers

range(1, 5)

→ [1,2,3,4,5]

reverse

Reverse array order

reverse(variables('rows'))

→ Reversed array

Logic & comparison

WDL has no operators — comparisons and boolean logic are all functions that take their arguments in parentheses.

Return a value by condition

if(greater(variables('n'), 0), 'pos', 'neg')

→ One of two values

equals

Test equality

equals(item()?['Status'], 'Open')

→ true / false

greater / less

Numeric comparison

greater(variables('total'), 1000)

→ true / false

greaterOrEquals / lessOrEquals

Inclusive comparison

lessOrEquals(variables('age'), 17)

→ true / false

and

All conditions true

and(variables('active'), variables('paid'))

→ true / false

Any condition true

or(equals(s, 'A'), equals(s, 'B'))

→ true / false

not

Invert a condition

not(empty(variables('rows')))

→ true / false

coalesce

First non-null value

coalesce(item()?['Nick'], item()?['Name'], 'Guest')

→ First with a value

Type conversion

int

Parse to integer

int(triggerBody()?['Qty'])

→ A whole number

float

Parse to floating point

float('123.45')

→ 123.45

string

Convert to text

string(variables('count'))

→ "42"

bool

Convert to boolean

bool('true')

→ true

json

Parse a JSON string to an object

json(triggerBody())

→ An object

Use after an HTTP action whose body is a string of JSON.

array

Wrap a value in an array

array(item())

→ A one-item array

base64

Encode text as base64

base64('hello')

→ Base64 text

base64ToString

Decode base64 to text

base64ToString(variables('enc'))

→ "hello"

decimal

Exact decimal value

decimal('19.99')

→ A decimal

Prefer decimal over float for money to avoid rounding drift.

Date & time

Stored timestamps are UTC. Convert to the user’s zone only for display.

utcNow

Current UTC timestamp

utcNow()

→ ISO 8601 string

formatDateTime

Format a timestamp

formatDateTime(utcNow(), 'dd MMM yyyy')

→ "13 Jun 2026"

addDays

Add days

addDays(utcNow(), 7)

→ One week out

addHours / addMinutes

Add smaller spans

addHours(utcNow(), -2)

→ Two hours ago

addToTime

Add an arbitrary span

addToTime(utcNow(), 3, 'Month')

→ A timestamp

startOfDay / startOfMonth

Snap to a boundary

startOfDay(utcNow())

→ Midnight today

dayOfWeek

Day-of-week number

dayOfWeek(utcNow())

→ 0 (Sun) to 6 (Sat)

ticks

Timestamp as a tick count

ticks(utcNow())

→ A big integer

Subtract two ticks values, then divide, to get elapsed time.

convertFromUtc

UTC to a target zone

convertFromUtc(utcNow(), 'GMT Standard Time')

→ Local time

convertTimeZone

Between two zones

convertTimeZone(t, 'UTC', 'Eastern Standard Time')

→ Converted time

Math

add / sub

Add or subtract

add(variables('total'), 5)

→ A number

mul / div

Multiply or divide

div(variables('total'), 2)

→ A number

div of two integers does integer division — wrap an argument in float() for decimals.

mod

Remainder after division

mod(17, 5)

→ 2

min / max

Smallest or largest argument

max(variables('a'), variables('b'))

→ A number

rand

Random integer in a range

rand(1, 100)

→ e.g. 42

Upper bound is exclusive.

Objects & JSON

null-safe access ?[ ]

Read a field without failing

body('Get_item')?['Author']?['Email']

→ A value or null

Chain ?[ ] through every level. One missing link otherwise breaks the whole expression.

addProperty

Add a field to an object

addProperty(item(), 'Processed', true)

→ New object

setProperty

Set/replace a field

setProperty(item(), 'Status', 'Done')

→ New object

removeProperty

Drop a field

removeProperty(item(), 'Temp')

→ New object

xpath

Query an XML document

xpath(xml(body('HTTP')), '//title/text()')

→ Matching nodes

coalesce

First non-null of several fields

coalesce(item()?['Mobile'], item()?['Phone'])

→ First with a value