Templating language

To create dynamic templates that can be used directly in our backend we use Go:s built-in templating language. Below is a brief description of the syntax.

Basic syntax

Some variables as described below can be included in messages templates and other config parameters. The template string uses double {{}} brackets with the path to the variable from the root object denoted with a dot (.).

Example

Your {{.installation.Name}} reported a temperature of {{.payload.value}}{{.payload.unit}}.

Using this template on an installation named "Summer house" with parameters value (24.5 )and unit (°C) in the POST data will result in a message like the following.

Your Summer house reported a temperature of 24.5°C

More details about Golang Templating can be found in their documentation.

Injected data

The following is a list of all data that is injected into the template when it's executed.

Var name	Description
.installation.ID	ID of the installation
.installation.Name	Name of the installation
.installation.ClientID	Client ID of the installation
.organization.ID	ID of the organisations that the installation belongs to
.organization.Name	Name of the organisations that the installation belongs to
.organization.Address.Address	Address of the organisations that the installation belongs to
.organization.Address.City	City of the organisations that the installation belongs to
.organization.Address.Country	Country of the organisations that the installation belongs to
.organization.Address.ZIP	ZIP code of the organisations that the installation belongs to
.organization.Email	Contact email of the organisations that the installation belongs to
.organization.Phone	Contact phone number of the organisations that the installation belongs to
.organization.Notes	Notes in the organisations that the installation belongs to
.payload.*	All JSON data included in the POST request when sending

Injected functions

Some special functions are injected into the templating engine as described below.

toTime

Converts the supplied time as seconds to a time object.

Happened at: {{ toTime .payload.timestamp }}

The output format can be specified according to Go time

Happened at: {{ (toTime .payload.timestamp).Format "2006-01-02 03:04:05" }}

toDuration

Converts a number of seconds to a human-readable time duration such as 2m or 5h.

Happened {{ toDuration .payload.age_seconds }} ago.

now

Returns a time object for the current timestamp (at execution of the message template).

Message executed at {{ now }}.

Advanced examples

This template specifies the number of decimals to use. The printf function accepts all format strings according to Go fmt.

Value is: {{ printf "%.2f" .payload.value}}

This template uses an if/else-if/else statement to change the text in the message based on the payload value. The - inside of the brackets removes spaces and newline characters.

{{- if lt .payload.value 0.0 -}}
Less than zero
{{- else if gt .payload.value 0.0 -}}
Greater than zero
{{- else -}}
It's zero
{{- end -}}

This template calculates the time difference between the timestamp in the message and when the template was executed.

Message timestamp was: {{ ((toTime .payload.timestamp).Sub now).Abs }} ago.