# Blockly Reference

One of the core feature that OpenHAB provides is writing rules to allow specific behaviour with the home automation system. The usual way of developing rules is by coding them like described in the Textual Rules.

However, this art of programming may become intimidating early on and shy away away people with few or almost no experience in programming. Therefore openHAB also provides a graphical way of writing rules which allows to put together rules in a rather visual way (even though some programming background may still help).

Introduction
Looking for help
Before using blockly
Blockly Youtube Tutorials
Blocks Overview
Tutorials or other useful information

# Introduction

The basic idea behind the visual paradigm and representation within openHAB is based on the Google Blockly Support (opens new window) which has been integrated and which provides the basic blocks for programming like the ones on the left and the right side of the below images

Blockly toolbox

blockly-toolbox-1 blockly-toolbox-2 blockly-toolbox-3

All of these provide general functionality that is not specific to openHAB itself. If you want to learn more about how to use them, search for the many blockly tutorials that are available. However, to leverage the full capabilities more than 50 specific blocks have been provided that are tailored for easy access of openHAB's capabilities.

This section provides a detailed description of the specific blocks and provides examples on how to use them. Note that some of the blocks (like voice, streaming or notifications) need some special setup within openHAB - in these case links to the respective documentation is provided. Also see this youtube Intro (opens new window) Quick Intro Blockly Rules

# Looking for help

A special mention should go towards the Help entry in a block context menu right click on any block that links to a resource that is usually very helpful to understand the context of that particular block. To retrieve the particular help for a block right click on a block to open the context menu and click on the help-entry:

context-help

There is also a help-button available in each section that links to the documentation of the whole section.

main-help-button

Please read this information first before asking questions in the forum. In case you ask for help please always post the respective code that is being generated.

Also there is a good intro about that topic can be viewed at youtube Various Help Documentation available in openHAB Blocky (opens new window)

# Before using blockly

Please visit Getting started with openHAB Blocklies before asking questions in the forum

# Blockly Youtube Tutorials

Three Youtube tutorials have been made available via the openHAB Youtube channel (opens new window):

# Blocks Overview

Also view youtube Overview of the Blockly Sections (opens new window)

# Items and Things

Items and Things are the major entities of openHAB (opens new window) to control and monitor the home.

See Items & Things section

# Timers and Delays

Timers and Delays are a little more complex but add important functionality to rules. Whilst the “Wait-For”-block is straightforward, the timer blocks should be well understood before being used - they may behave differently than expected. This chapter explains what these blocks do, sometimes displaying generated code to explain what is happening behind the scenes.

See Timers and Delays section.

# Date Handling

Date blocks are used as input parameters for other blocks. Some of these blocks are used by ephemeris blocks, whilst others are used in the persistence section. Therefore blocks are typed to assure correct connection to other blocks.

See Date Handling section.

# Ephemeris

The ephemeris category provides blocks with calendar functionality. The blocks can be used to determine what type of day today is, or a number of days before or after today is. For example, a way to determine if today is a weekend, a bank holiday, someone’s birthday, trash day, etc.

See Ephemeris section.

# Voice and Multimedia

This section deals with playing or streaming audio to an audio sink e.g a speaker or saying a text via using any Text-to-Speech API (e.g. Google's API)

See Voice and Multimedia section.

# Notifications

For use with your openHAB cloud (opens new window) account, these blocks can be used to send notifications to relevant connected devices. Notifications can be used as push message to devices running the openHAB client.

See Notifications section.

# Persistence

Persistence blocks enable access of historical data stored by the default persistence service.

See Persistence section.

# Value Storage

These blocks enable storing information for a rule that is kept after the rule has run, so it can be reused when the rule is run again later in stateful way.

See Value Storage section.

# Run & Process (Rules, Scripts and Transformations)

This section allows calling rules or other scripts, retrieving attributes provided by the rule context or transforming values via different conversion methods (e.g. map, regex, jsonpath)

See Run and Process section.

# Logging

This section allows calling rules or other scripts, retrieving attributes provided by the rule context or transforming values via different conversion methods (e.g. map, regex, jsonpath)

See Logging section.

# openHAB Extensions to the Standard

This section explains only the blocks that have been added to the standard blocks by openHAB

See openHAB Extensions to the standard section.

# Tutorials or other useful information

Caught a mistake or want to contribute to the documentation? Edit this page on GitHub (opens new window)

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