Monthly Archives: August 2018

Angular Material Toggle Buttons Group with Binding

Angular Material Toggle Buttons Group with Binding

In this post we are going to create an Angular App to use Button toggle groups from Angular material. We are going to do data binding of these buttons and generate the buttons using a list in the code behind in the component class.



Let’s first create a simple Angular App using Angular CLI.

ng new button-toggle-app

ng new button-toggle-app

Now let’s install the necessary npm modules to use the toggle buttons.

npm install --save @angular/material @angular/cdk @angular/animations

npm install –save @angular/material @angular/cdk @angular/animations

Let’s import the material modules to app module. This allows them to be used in the whole module.

We need to update styles.css to use angular material theme:

Let’s introduce an array in the code behind (app.components.ts). We are going to use this array to create the list of toggle buttons in UI.

Here we are using the toggleButtons collection with *ngFor. We are binding the individual item to the value property of the toggle button. Please note that we are allowing multiple values to be selected in the button group. We are then displaying the selected options just below the button toggle group.

Default Options & Selected Values

Now let’s introduce the idea of default options when the page is loaded. We can bind value property in the button group to drive this. This can be bound with a string array in the code behind. Here is how we can change the template:

And here is how we can introduce the property in the code behind:

Handling Toggle Event

We can handle toggle events for individual button. We can even pass the selected / unselected value in the button group. It must be remembered that it handles the binding before emitting events so if you want to use the set value of the bound property, it should be alright.

Here is how we can update the code behind. We have just added a method to handle the value change of the buttons. We are just printing the current value and all the values currently selected by the button group.

Now we just need to use it in the template.

Code Repository

Kafka-Consumer-Groups – Kafka CLI Tools

Kafka-Consumer-Groups – Kafka CLI Tools

Kafka-Consumer-Groups is a CLI tool which can be used to get the message consumption from Kafka. The tool can be used to get the list of topics and partitions consumed by a consumer group. It also details if a consumer is lagging in consumption of the messages.

First we need to get the list of consumer groups. -list switch is used to get the list of consumer groups.

Now we have the details of a consumer group, we can get the detail of message consumption from the kafka topic and its partitions.

Here is the output:

Output Details

Output Details

Kafka Streams – Resetting Application State

Kafka Streams – Resetting Application State

I the previous post, we discussed that we might need to reprocess data during development during application development. Since Kafka Streams ensures the application state, it doesn’t pull and reprocess data. In this case, you might find yourself keep waiting for the join operations to get triggered, but to your disappointment, you might not see the breakpoints being hit.

There are two alternate ways which can be used during application development and debugging ensuring the reprocessing of data.

Here is the streams configuration for our Kafka Streams application:

Use New Application Id

One possible solution is to use the new application state each time you need to re-process in your development environment. You can just use a random number for the configuration. It is very common to destroy the whole confluent environment using confluent destroy command. So if it looks non-manageable anytime, you can always destroy it. I wouldn’t recommend this as there is an alternate solution available which is also very easy to use.

Application Reset Tool

Alternatively you can use Kafka Application reset tool. Here we are resetting the state of application with myApplicationId id. After executing the command, the offset should be set to the beginning of input topics. It would also delete all intermediate topics.