This final example will show you how to build a micro blog service with only a few nodes in Node RED. You’ll be using the MongoDB node as a storage for posts, http nodes to provide end points for the service and the html node to format the micro-blog web page. Continue reading “Node-RED: Lecture 6 – Example 6.9 Creating a Blog Site With Node-RED”
Tag: function node
Node-RED: Lecture 6 – Example 6.7 Multiple inputs to a function node
Function nodes in Node-RED were designed to process messages as single entities. However, in some cases your functions might depend on two separate data sources. There are many ways to handle multiple inputs to a function node. This example shows one approach based on context data.
Continue reading “Node-RED: Lecture 6 – Example 6.7 Multiple inputs to a function node”Node-RED: Lecture 6 – Example 6.6 Getting earthquake data from an external API
This example demonstrates how to get data from an external API and how to separate that data using a function node. We will use data from an external API that provides access to earthquake data which is made available by the US geological survey (USGS). Continue reading “Node-RED: Lecture 6 – Example 6.6 Getting earthquake data from an external API”
Node-RED: Lecture 6 – Example 6.5 Defining and using an iterator sub-flow
As mentioned in lecture 5, sub-flows can be used to package up functions into nodes in your node palette. In this example, you’ll create a sub-flow that processes an array of values in a message payload and outputs a new processed array[3]. Continue reading “Node-RED: Lecture 6 – Example 6.5 Defining and using an iterator sub-flow”
Node-RED: Lecture 6 – Example 6.4 Using the context element to share a function and make it accessible to all functions in the canvas
This example shows how to use the context object and its global element to share data across function nodes. Continue reading “Node-RED: Lecture 6 – Example 6.4 Using the context element to share a function and make it accessible to all functions in the canvas”
Node-RED: Lecture 6 – Intermediate flows
This lecture will build on the ideas you saw in lecture 5 and focus on examples that explore some of the key concepts from that lecture. These include the ideas of context, messages and sub-flows. The examples in this lecture are a little more complex than previous examples Continue reading “Node-RED: Lecture 6 – Intermediate flows”
Node-RED: Lecture 6 – Example 6.3 Using context to generate rolling averages
A special module called context, used to store data between function invocations, is available to function nodes. This can be useful when the function needs to retain state to do its processing. For example, in a typical Industrial IoT scenario, Continue reading “Node-RED: Lecture 6 – Example 6.3 Using context to generate rolling averages”
Node-RED: Lecture 6 – Example 6.2 Counting words in a string using a function Node
Next, let’s write a more complex function node that receives some text in a message payload, then outputs multiple messages containing all individual words and the number of times each word was used. Continue reading “Node-RED: Lecture 6 – Example 6.2 Counting words in a string using a function Node”