Response Templating - Miscellaneous Helpers

This article describes some useful helpers that don’t neatly fit into any of the other categories.


You can create a string variable of own using the assign helper, then use it later in your template e.g.:

{{#assign 'myCapitalisedQuery'}}{{capitalize}}{{/assign}}

Capitalised query: {{myCapitalisedQuery}}

Val helper

The val helper can be used to access values or provide a default if the value is not present. It can also be used to assign a value to a variable much like the assign helper. The main difference between val and assign is that val will maintain the type of the date being assigned whereas assign will always assign a string.

{{val or='default'}} // the value of or 'default' if it's not present
{{val default='default'}} // the value of or 'default' if it's not present
{{val}} // the value of or null if it's not present
{{val or='default' assign='myVar'}} // assign the value of or 'default' to myVar
{{val assign='myVar'}} // assign the value of to myVar

{{val (array 1 2 3) default='123'}} // [1, 2, 3]
{{val 'value for myVar' assign='myVar'}}{{myVar}} // value for myVar
{{val null or='other value for myVar' assign='myVar'}}{{myVar}} // other value for myVar
{{val 10 assign='myVar'}}{{#lt myVar 20}}Less Than{{else}}More Than{{/lt}} // Less Than


The size helper returns the size of a string, list or map:

{{size 'abcde'}}               // Returns 5
{{size request.query.things}}  // Returns number of values in query param 'things'


The with helper creates a nested scope, allowing you to reference attributes on an object without fully qualifying it each time.

For instance, given a variable whose value is an object with the properties id and position, with allows these to be accessed without qualifying each time:

{{#with myObject}}
  ID: {{{id}}}
  Position: {{{position}}}


The range helper emits an array of integers between the bounds specified in the first and second parameters (both of which are mandatory).

{{range 3 8}}
{{range -2 2}}

As mentioned above, you can use this with randomInt and each to output random length, repeating pieces of content e.g.

{{#each (range 0 (randomInt lower=1 upper=10)) as |index|}}
id: {{index}}


The array helper emits an array containing exactly the values specified as parameters.

{{array 1 'two' true}}

Passing no parameters will result in an empty array being returned.


Array add & remove helpers

The arrayAdd and arrayRemove helpers can be used to add or remove elements from an array based on a position value or the start or end keywords. If no position is specified, the element will be added or removed from the end of the array.

{{arrayAdd (array 1 'three') 2 position=1}} // [1, 2, three]
{{arrayAdd (array 1 'three') 2 position='start'}} // [2, 1, three]
{{arrayAdd (array 1 'three') 2 position='end'}} // [1, three, 2]
{{arrayAdd (array 1 'three') 2}} // [1, three, 2]

{{arrayRemove (array 1 2 'three') position=1}} // [1, three]
{{arrayRemove (array 1 2 'three') position='start'}} // [2, three]
{{arrayRemove (array 1 2 'three') position='end'}} // [1, 2]
{{arrayRemove (array 1 2 'three')}} // [1, 2]

arrayJoin helper

The arrayJoin helper will concatenate the values passed to it with the separator specified:

{{arrayJoin ',' (array 'One' 'Two' 'Three')}} // One,Two,Three
{{arrayJoin ' - ' 'a' 'b' 'c'}} // a - b - c
{{arrayJoin ', ' (range 1 5)}} // 1, 2, 3, 4, 5
{{arrayJoin (pickRandom ':') (array 'One' 'Two' 'Three')}} // One:Two:Three
{{arrayJoin '' (array 'W' 'i' 'r' 'e' 'M' 'o' 'c' 'k' ' ' 'R' 'o' 'c' 'k' 's')}} // WireMock Rocks

You can also specify a prefix and suffix to be added to the start and end of the result:

{{arrayJoin ',' (array 'One' 'Two' 'Three') prefix='[' suffix=']'}} // [One,Two,Three]
{{arrayJoin ' * ' (array 1 2 3) prefix='(' suffix=')'}} // (1 * 2 * 3)

The arrayJoin helper can also be used as a block helper:

{{#parseJson 'myThings'}}
  { "id": 1, "name": "One" },
  { "id": 2, "name": "Two" },
  { "id": 3, "name": "Three" }
[{{#arrayJoin ',' myThings as |item|}}
"name{{}}": "{{}}"
{{/arrayJoin}}] // [{ "name1": "One" }, { "name2": "Two" }, { "name3": "Three" }]

// or the same example with the prefix and suffix parameters
{{#parseJson 'myThings'}}
    { "id": 1, "name": "One" },
    { "id": 2, "name": "Two" },
    { "id": 3, "name": "Three" }
{{#arrayJoin ',' myThings prefix='[' suffix=']' as |item|}}
    "name{{}}": "{{}}"
{{/arrayJoin}} // [{ "name1": "One" }, { "name2": "Two" }, { "name3": "Three" }]