Blog - kimserey lam

Oct 30, 2020

Kafka Schema Registry With Avro

In previous posts, we have seen how to setup Kafka locally and how to write a producer and consumer in dotnet. The topic on which producer produces messages and consumer consumes messages accepts messages of any type, hence an agreement needs to be made between producer and consumer on a contract so that whatever is being produced can be understood at consumption. In order to enforce that contract, it is common to use a Schema Registry. In this post, we will look at how we can setup and use a schema registry, and we will look at how we can create an Avro schema to enforce produced and consumed data.

Oct 23, 2020

Create Kafka Producer And Consumer In Dotnet And Python

Last week we looked at how we could setup Kafka locally in Docker. Continuing along our Kafka series, we will look at how we can create a producer and consumer using confluent-kafka-dotnet.

Oct 16, 2020

Setup Local Kafka With Docker

When writing Kafka producer or consumer applications, we often have the need to setup a local Kafka cluster for debugging purposes. In this post, we will look how we can setup a local Kafka cluster within Docker, how we can make it accessible from our localhost and how we can use Kafkacat to setup a producer and consumer to test our setup.

Oct 09, 2020

Generate Fake Data In Python With Faker

Reducing repetition in codebase is a well understood concept in Software development. When writing features, we try to use existing functionalities so that we don’t duplicate similar logic. Surprisingly, this concept is often skipped when writing tests where we end up with a hundred over test cases with repeated construction of input objects to fit all possible scenarios being tested. In most languages (I haven’t checked all of them), developers have addressed such problem by providing ways to fake inputs. In today’s post, we will look into Python Faker package and how to use it to improve code reuse.

Oct 02, 2020

Angular Async Pipe

The async pipe is used in Angular to unwrap a value from an asynchronous primitive. An asynchronous primitive can either be in a form of an observable or a promise. It is one of the most important pipes of Angular as it allows us to remove the complexity of handling subscription to data coming from asynchronous sources like HTTP clients. The code of the async pipe is surprisingly simple and understanding it will allow us to avoid traps like the default null value. So in today’s post, we will reimplement the async pipe in a toned down version of it.

Sep 25, 2020

Create Stored Procedure In Mysql

A stored procedure in MySQL acts as a method stored in the database. It has a name and accepts a set of arguments and can be invoked via CALL statement. In this post we will look at how we can define a stored procedure, how the parameters and variables work, and lastly how we can define transactions and handle exceptions accordingly.

Sep 18, 2020

Handle Polymorphic Array Serialization With Marshmallow

Few months ago we looked into Marshmallow, a Python serialisation and validation framework which can be used to translate Flask request data to SQLAlchemy model and vice versa. In today’s post we will look at how we can serialise an array containing polymorphic data.

Sep 11, 2020

Postgres Window Function

Window functions are calcultions done accross a set of rows in relation to the current row. In Postgres, we can use window functions with the keywords OVER to calculate useful aggregate functions like average, ranking or count over a partition of the data. In today’s post we will look at example of window function usage.

Sep 04, 2020

Ngrx Metareducer

When building Angular application with Ngrx, it is helpful to see the action flowing into our states for debugging. The quick and easy way to debug is to make use of the Redux DevTools which shows the list of actions and provide time travelling functionalities. Another way is to simply log the action, the state prior applying the action, and the resulting state. In Ngrx, we are able to do that using a Meta-reducer.

Aug 28, 2020

Postgres Full Text Search

In today’s post we will look at how PostgreSQL Full Text Search functionalities can be used to retrieved ranked documents. We’ll start by looking at the basics of matching documents, then we’ll move on to how we can define indexes for performance improvement and we’ll end by looking at weights and ranking.

Aug 21, 2020

Debugging Angular App With Chrome Devtools

When developing Angular application, or any sort of frontend application, we ensure that the application works properly by displaying it on the browser. Chrome comes with built-in devtools enhancing greatly our debugging toolkit. In today’s post we will look at the source panel of the devtools and discover the most important functionalities.

Aug 14, 2020

Getting Started With Sqlalchemy Orm

In a previous post, we talked about Alembic which is a migration tool built on top of SQLAlchemy. SQLAlchemy is a Python SQL toolkit and Object Relational Mapper (ORM). In today’s post, we will look at how the ORM part can be leverage to easily create and manage a simple database schema.

Aug 07, 2020

Using Vscode Task To Detect Compilation Errors In Angular

Working with Angular is Visual Studio Code (VSCode) is extremely easy. One feature which allowed me to quickly debug and find errors is the task feature combined with the Angular CLI. In today’s post, we will see how we can setup a task that uses the Angular CLI to highlight compilation problems in the application.

Jul 31, 2020

Understand Exportas In Angular Directive

A few weeks ago we looked into ViewChild and ContentChild. We saw how template variable could be used to get references on the element they were defined on. In today’s post we will see how exportAs facilitates the creation of template variables.

Jul 24, 2020

Python Interactive With Vscode

In a previous post we talked about Jupyter notebook. We looked at the support of notebooks from Visual Studio Code and how we could write a notebook almost like a story with interactive code. Continuing on the same line, in today’s post we will be looking at Visual Code Python Interactive and see how it can be used to write Python scripts or quickly test prototypes.