Hoverfly can build responses dynamically through templating. This is particularly useful when combined with loose matching, as it allows a single matcher to represent an unlimited combination of responses.

Enabling Templating

By default templating is disabled. In order to enable it, set the templated field to true in the response of a simulation.

Getting data from the request

Currently, you can get the following data from request to the response via templating:

Field Example Request Result
Request scheme {{ Request.Scheme }} http://www.foo.com http
Query parameter value {{ Request.QueryParam.myParam }} http://www.foo.com?myParam=bar bar
Query parameter value (list) {{ Request.QueryParam.NameOfParameter.[1] }} http://www.foo.com?myParam=bar1&myParam=bar2 bar2
Path parameter value {{ Request.Path.[1] }} http://www.foo.com/zero/one/two one
Method {{ Request.Method }} http://www.foo.com/zero/one/two GET
jsonpath on body {{ Request.Body “jsonpath” “$.test” }} { “id”: 123, “username”: “hoverfly” } 123
xpath on body {{ Request.Body “xpath” “/root/id” }} <root><id>123</id></root> 123
State {{ State.basket }} State Store = {“basket”:”eggs”} eggs

Helper Methods

Additional data can come from helper methods. These are the ones Hoverfly currently support:

Description Example Result
The current UTC date time, formatted in iso8601 {{ iso8601DateTime }} 2006-01-02T15:04:05Z
The current UTC date time, formatted in iso8601, with days added {{ iso8601DateTimePlusDays Request.QueryParam.plusDays }} 2006-02-02T15:04:05Z
The current UTC date time, in the format specified {{ currentDateTime “2006-Jan-02” }} 2018-Jul-05
The current UTC date time, in the format specified, with duration added {{ currentDateTimeAdd “1d” “2006-Jan-02” }} 2018-Jul-06
The current UTC date time, in the format specified, with duration subtracted {{ currentDateTimeSubtract “1d” “2006-Jan-02” }} 2018-Jul-04
A random string {{ randomString }} hGfclKjnmwcCds
A random string with a specified length {{ randomStringLength 2 }} KC
A random boolean {{ randomBoolean }} true
A random integer {{ randomInteger }} 42
A random integer within a range {{ randomIntegerRange 1 10 }} 7
A random float {{ randomFloat }} 42
A random float within a range {{ randomFloatRange 1.0 10.0 }} 7.4563213423
A random email address {{ randomEmail }} LoriStewart@Photolist.com
A random IPv4 address {{ randomIPv4 }}
A random IPv6 address {{ randomIPv6 }} 41d7:daa0:6e97:6fce:411e:681:f86f:e557
A random UUID {{ randomUuid }} 7b791f3d-d7f4-4635-8ea1-99568d821562
Replace all occurrences of the old value with the new value in the target string {{ replace Request.Body “be” “mock” }} (where Request.Body has the value of “to be or not to be” to mock or not to mock


When using template helper methods such as currentDateTimeAdd and currentDateTimeSubtract, durations must be formatted following the following syntax for durations.

Shorthand Type
ns Nanosecond
us/µs Microsecond
ms Millisecond
s Second
m Minute
h Hour
d Day
y Year

Example Durations

5m 5 minutes
1h30m 1 hour 5 minutes
1y10d 1 year 10 days

Date time formats

When using template helper methods such as currentDateTime, currentDateTimeAdd and currentDateTimeSubtract, date time formats must follow the Golang syntax. More can be found out here https://golang.org/pkg/time/#Parse

Example date time formats

Mon, 02 Jan 2006 15:04:05 MST
Jan _2 15:04:05

Conditional Templating, Looping and More

Hoverfly uses the https://github.com/aymerick/raymond library for templating, which is based on http://handlebarsjs.com/

To learn about more advanced templating functionality, such as looping and conditionals, read the documentation for these projects.