vis-jsontemplate

Overview

Adapter to visualize JSON data and other data in Vis/Vis2. You can customize the output of the data with a template system. In the templates you can include HTML, CSS and Javascript. The template system used was ejs. You can try out the basic features here in the online playground. https://ionicabizau.github.io/ejs-playground

The jsontemplate widget was previously available in the rssfeed (for vis1) and vis-2-widgets-ovarious adapters. The widgets will be removed from these adapters in the near future.

Table of Contents

• Overview
• Installation
• Configuration
• vis and widgets
  • JSON Template
  • Advanced use case
  • More Use Cases
• Templatesystem
  • Very Important Note for use in vis / vis-2
  • Curly braces in CSS and JSON
  • Use of setInterval
  • Developing templates with AI
• Tags
• Example object
• Development and Debugging
  • Vis1 Widgets
  • Vis2 Widgets
• Todo
• Changelog
• License

Installation

Install the adapter as normal from the stable repository. If you want to test new features or bug fixes you can also install the adapter from the beta repository. For Features and news, please see the Test and Support thread for this adapter in the iobroker forum.

After Installation the adapter should then be displayed in the adapter section in the iobroker. Sometimes it happens that the changes are not visible, especially with web changes (widgets / configuration dialog), the following command may have to be executed on the command line:

iobroker upload jsontemplate

In the right area in the line of the adapter, an instance can be added using the plus button

Configuration

This adapter does not have a configuration dialog in the admin area.

vis and widgets

The following widgets actually exists

• JSON Template - you can define a custom template to show any JSON-Data in vis.

JSON Template

Using this widget, any data point with JSON data can be displayed as desired. The display is done using a template format, which can be thought of as a combined form of HTML code + JavaScript + CSS + special tags that control the display of the JSON attributes. JSONTemplate now supports async calls with await.

For details on the template system, see chapter Template based on examples

Available data objects in the template:

The additional datapoints can be accessed by A) the name of the datapoint

<%- dp["0_userdata.0.test"] %>
<%- dp["0_userdata.0.abc"] %>

B) Indexnumber of the datapoint (the number always start with 0)

<%- dp[Object.keys(dp)[0]] %>
<%- dp[Object.keys(dp)[1]] %>

C) An optional variable name configured for the datapoint. For a datapoint 0_userdata.0.selectwrite, variable name dpwrite, and value abc:

<%- dpwrite %>          <!-- 0_userdata.0.selectwrite -->
<%- dpwrite_value %>    <!-- abc -->
<%- dp[dpwrite] %>      <!-- abc -->

Example output of data, widget and style in the template

<%- JSON
    .stringify(style, null, 4)
    .replace(/\n/g, '<br>')
    .replace(/ /g, '&nbsp;'); %>

If an error occurs, it is displayed in the widget and output to the browser console (F12).

Advanced use case

In the examples above, only the pure output was covered. The template can now also be enriched with HTML tags to achieve a specific layout. Here is an example:

<h3>Output</h3>
<style>
    .mycssclassproperty {
        color: green;
    }
    .mycssclassdata {
        color: red;
    }
</style>
<% for (var prop in data.oneobject) { %>
<div>
    <span class="mycssclassproperty"><%- "data.oneobject." + prop + " = " %></span>
    <span class="mycssclassdata"><%- data.oneobject[prop] %></span>
</div>
<% } %>

Result:

    data.oneobject.attribute1 = 1
    data.oneobject.attribute2 = 2

(In Markdown colors aren't visible)

More Use Cases

• Use Case Async calls
• Use Case loading scripts
• Use Case Tasklist
• Use Case public-transport
• Use Case simple gauge
• Use Case Github Issues and PRs
• Use Case FRITZ!Box call list

Templatesystem

Very Important Note for use in vis / vis-2

Curly braces in CSS and JSON

The binding mechanism in vis / vis-2 uses the pattern { ... } to detect binding expressions within HTML. For this reason, when specifying CSS or JSON, the curly braces must always be placed on separate lines. Otherwise, the content of the vis widget will be overwritten with undefined.

Example

#<%- widgetid %> { height: 100%; display: flex; flex-direction: column; overflow: hidden; }

must be written as follows:

#<%- widgetid %> {
    height: 100%; display: flex; flex-direction: column; overflow: hidden;
}

Use of setInterval

Please do not use setInterval. Since the template is re-invoked every time a data point changes, any existing setInterval calls cannot be properly cleared. Consequently, an increasing number of overlapping setInterval calls accumulate over time; this consumes RAM and can lead to unpredictable side effects. While reloading the page can resolve this issue, the code should not be implemented in this manner. As an alternative, such scenarios should be implemented using setTimeout.

Developing templates with AI

To simplify the process of creating templates for everyone, I have prepared detailed documentation including prompts and descriptions:

• English
• German

Tags

The template system works with certain tags. The tags used mean the following

Everything that is outside of these tags is displayed exactly as it is or if it is HTML interpreted as HTML. Within the template you have 2 predefined variables available

Example object

For all the following examples the following json is used.

{
    "onearray": ["one", "two"],
    "oneobject": {
        "attribute1": 1,
        "attribute2": 2
    },
    "onenumber": 123,
    "onetext": "onetwothree"
}

Attributes could be output as follows

Template:

<%- data.onenumber %>
<%- data.onetext %>

Result:

    123 onetwothree

Arrays can be accessed via an index. The index always starts with 0. However, there are also fake arrays where the index does not start with 0 or even consists of text. Here the rules for objects apply. In the example above, this would be

Template:

<%- data.onearray[0] %>
<%- data.onearray[1] %>

Result:

    one two

If you try to output an array directly without an index, the template outputs all elements separated by commas

Template:

<%- data.onearray %>

Result:

    one,two

Arrays can also consist of a collection of objects. The example here contains only a simple array. An example of arrays with objects will be given later.

Template:

<% for (var i = 0; i < data.onearray.length ; i++ ) { %>
<%- data.onearray[i] %>
<% } %>

Result:

    one two

Objects can contain individual attributes, arrays or objects again. This means that JSON data can be nested to any depth.

Attributes of an object can be addressed using dot notation or bracket notation. The dot notation only works if the attribute conforms to certain naming conventions (first character must be a letter, rest numbers or letters or underscore). The bracket notation also works for attributes that do not conform to the naming convention.

Dot notation:

Template:

<%- data.oneobject.attribute1 %>

Bracket notation:

Template:

<%- data.oneobject["attribute1"] %>

Result for both examples:

    1

Loop over the attributes of an object

Template:

<% for (var prop in data.oneobject) { %>
<%- "data.oneobject." + prop + " = " + data.oneobject[prop] %>
<% } %>

Result:

    data.oneobject.attribute1 = 1
    data.oneobject.attribute2 = 2

Development and Debugging

Vis1 Widgets

• Install dev-server
• Start dev-server with --noStart option
• On first start install additional adapter web and vis1
• start vscode launch configuration "vis-1 editor"
• if widgets are not available, upload adapter in expert mode on the adapter page
• now you can set breakpoints in vscode in the jsontemplate.js file
• if you change something in the js file the source must be compiled to the dist folder with npm run build-vis1widgets command.
• the dev-server uploads the changed files to iobroker, but for vis1 you have to execute the iob visdebug command to reload the widgets
• to translate additional entries in en.json use the translate-widgets-vis1 command

Vis2 Widgets

• Install dev-server
• Open a new vscode window (2. instance)
• clone vis2 repository
• follow the instructions in the readme of the vis2 repository in chapter Development and Debugging. you don't have to fork the repository. we only need a running instance of the vis2 adapter
• start vis 2 with npm run start
• back in in the vscode instance of this adapter
• Start dev-server with --noStart option
• start vscode launch configuration "vis-2 editor"
• now you can set breakpoints in vscode in the jsontemplate.js file
• if you change something you don't have to do anything else, because vite supports hot reload. sometimes it is useful to reload vis2 with F5
• to translate additional entries in en.json use the translate-widgets-vis2 command

Todo

• tbd

Changelog

4.6.1 (2026-07-31)

• Improved error output.

4.6.0 (2026-07-30)

• some changes. see readme/below

Changes 2026-07-30

• add optional variable names to extra datapoints

4.5.0 (2026-07-29)

• some changes. see readme/below

Changes 2026-07-29

• repair widget rendering
• add search and fullscreen to ejs-edit for vis-2 widget
• improve ki documentation for regex expressions
• improve vis-2 ejs edit theme for dark mode

4.4.5 (2026-07-22)

• fix packages for vis-2

4.4.4 (2026-07-22)

• some changes. see readme/below

Changes 2026-07.22

• change documentation that in the template the widgetid is available and not widgetID
• add documentation for the usecase simple gauge
• add documentation for a responsive FRITZ!Box call list
• Due to an inconsistency between the vis1 and vis2 widgets, both widgetid and widgetID are now passed to the template.

License

MIT License

Copyright (c) 2021-2026 oweitman oweitman@gmx.de

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.