How to fix Failed to load ApplicationContext in Spring (Boot) applications (6 mins read).
Some common issues with Spring dependency injection and how to fix them.
Tag blogumentation
Converting an x5c from a JSON Web Key to a PEM with Node.JS (1 mins read).
How to convert a JWK's x5c to a PEM-formatted certificate with Node.JS.
by 
Jamie Tanna
.
#blogumentation
#nodejs
#jwks
#jwk
#certificates
#pem
#x509.
Extracting x5cs from a JSON Web Key Set (JWKS) to PEM files with Node.js (1 mins read).
How to extract the full chain of certificates from a JWKS' x5c parameter to files.
by Jamie Tanna
.
#blogumentation
#nodejs
#jwks
#jwk
#certificates
#pem
#x509.
Generate a running mock server from an OpenAPI specification using Prism (3 mins read).
Using Stoplight's prism tool to run a stubbed server from an OpenAPI specification, for better testing.
Gotcha: checked and unchecked exception handling from Spring WebFlux WebClient (2 mins read).
How checked and unchecked exceptions may appear when testing your WebClient code.
by Jamie Tanna
.
#blogumentation
#spring
#spring-boot
#java
#testing.
Accessing the response body with Spring WebFlux WebClient with onStatus (1 mins read).
How to access the body of an (error) response when using WebClient's onStatus method.
by Jamie Tanna
.
#blogumentation
#spring
#spring-boot
#java.
Running a command on a visual selection in Vim (1 mins read).
How to pipe the text in a visual selection to a command, either to run it, or to replace the text in the seletion.
by Jamie Tanna
.
#blogumentation
#vim
#neovim
#command-line.
Updating the CA Certificate bundle in Chef Installations (3 mins read).
How to update/add new certificates to the Certificate Authority Certificate Bundle in a Chef Development Kit / Workstation installation.
by Jamie Tanna
.
#blogumentation
#chef.
Automagically formatting on save, with Neovim and Language Server Protocol (LSP) (1 mins read).
How to use Neovim's Language Server Protocol (LSP) support to autoformat code on a file's save.
Gotcha: Segfault when HTTP headers include newlines with Go (2 mins read).
Why you may be receiving a segfault when using http.Client with HTTTP headers that include newlines.
by Jamie Tanna
.
#blogumentation
#go.
Converting Spring Boot Property Variables to Environment Variables with Go (1 mins read).
A command-line script to convert a Spring Boot property to an environment variable.
by Jamie Tanna
.
#blogumentation
#go
#command-line
#spring-boot.
Pretty Printing JSON Web Tokens (JWTs) on the Command Line using Go (2 mins read).
How to easily introspect and pretty print a signed JWT (JWS) or an encrypted JWT (JWE) on the command line using Go.
by Jamie Tanna
.
#blogumentation
#go
#command-line
#jwt
#json
#pretty-print.
Gotcha: Field casing is important when marshalling structs to JSON in Go (2 mins read).
Why you may be missing fields from your structs in your Go json.Marshal calls.
by Jamie Tanna
.
#blogumentation
#go
#json.
Testing @Scheduled annotations with Spring (Boot) (2 mins read).
How to test your Spring (Boot) scheduling without waiting for hours.
Pretty Printing JSON on the Command Line with Go (1 mins read).
Using Go's JSON module to pretty print JSON objects from the command line.
Reading all of stdin on the command-line with Go (1 mins read).
How to read the whole of stdin, up to EOF, with Go.
Exporting a Git repo as an archive (1 mins read).
How to export a Git repo as an archive format, such as a .tar.gz or a .zip.
by Jamie Tanna
.
#blogumentation
#git.
How to interpolate a property inside Spring Security @PreAuthorize / @PostAuthorize (3 mins read).
How to use the value of a property in a Spring Security authorization statement.
by Jamie Tanna
.
#blogumentation
#java
#spring
#spring-boot
#spring-security.
Combining an Audio-only and Video-only MP4 with ffmpeg on the command-line (1 mins read).
How to use ffmpeg to combine two MP4 files, where each file contains audio and video separately.
Adding a Wiretap to a Spring WebFlux WebClient to Log All Request/Response Data (2 mins read).
How to log all request/response data from a Spring Webflux WebClient.
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#spring.
Determining if the Spring Boot Application is Running in Debug or Trace Mode (3 mins read).
How to determine if your Spring Boot application is running in debug mode, for instance to selectively enable other features of your application.
Simplifying Spring (Boot) ExceptionHandlers by extending ResponseStatusException (1 mins read).
How to drive HTTP response status codes from exceptions by extending Spring's ResponseStatusException.
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#spring.
Bundling Multi-File OpenAPI Documents into a Single File (2 mins read).
Looking at the options we have for converting a multi-file OpenAPI specification to a single document.
Generating Favicons using ImageMagick on the Command-Line (1 mins read).
How to generate a multi-size favicon.ico on the command-line using ImageMagick.
by Jamie Tanna
.
#blogumentation
#command-line
#imagemagick.
Excluding Filters When using WebMvcTest (1 mins read).
How to exclude specific Filters from running when performing WebMvcTests.
by Jamie Tanna
.
#blogumentation
#java
#spring
#spring-boot
#testing
#tdd.
Capturing HTTP Requests with okhttp's MockWebServer.takeRequest (1 mins read).
How to use MockWebServer's takeRequest method to verify that HTTP request(s) are sent correctly.
by Jamie Tanna
.
#blogumentation
#java.
Integration Testing Your Spring WebClients with okhttp's MockWebServer (5 mins read).
How to write integration tests using MockWebServer with Spring Boot, for use with WebClients.
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#testing
#tdd.
Generate Plain Old Java Objects (POJOs) from OpenAPI Model Definitions with Gradle (2 mins read).
How to generate POJOs really quickly and easily, with no manual work, using the Gradle openapi-generator Plugin.
Running Elements API Viewer to Verify Local OpenAPI/Swagger Documents (2 mins read).
How to run Elements UI locally to visualise OpenAPI documents.
I don't think you should be logging that? 😳 (12 mins read).
Common pitfalls and dangerous things that you should be watching out for in your log messages.
by Jamie Tanna
.
#blogumentation
#logs.
Validating a MockMvc Response Has No Content Type (1 mins read).
How to validate, in a MockMvc test, whether the response has no content-type nor a body.
by Jamie Tanna
.
#blogumentation
#spring
#spring-boot
#testing.
Replacing Text in Vim with the Output of a Command (1 mins read).
How to replace text under the cursor with the output of a command.
by Jamie Tanna
.
#blogumentation
#vim
#neovim
#command-line.
Integration Testing Your Spring RestTemplates with RestClientTest, using spring-test (8 mins read).
How to write integration tests using RestClientTest with Spring Boot, for use with RestTemplate and RestTemplateBuilders.
by Jamie Tanna
.
#blogumentation
#java
#spring
#spring-boot
#testing
#tdd.
Running Swagger UI to Verify Local OpenAPI/Swagger Documents (2 mins read).
How to run Swagger UI locally to visualise OpenAPI documents.
Getting Started with jMolecules and the (Classical) Onion Architecture, with a Spring Boot project (6 mins read).
A guided example of converting a Spring Boot project to the Onion Architecture pattern.
by Jamie Tanna
.
#blogumentation
#java
#architecture
#spring-boot
#onion-architecture
#jmolecules
#archunit.
How to Create and Unit Test Java Bean Validation Annotations (12 mins read).
A guided example through what the different type of annotation ElementTypes are, with respect to Bean Validation, and how to write unit tests for them.
by Jamie Tanna
.
#blogumentation
#java
#bean-validation
#testing
#tdd.
Codifying Your Technical / Architectural Standards with ArchUnit (7 mins read).
How to use ArchUnit to codify your technical standards to reduce code review requirements, and arrive at a more consistent codebase.
by Jamie Tanna
.
#blogumentation
#java
#archunit
#code-review.
Appending to a Querystring using Go (1 mins read).
How to append query parameters in a URL in Go.
by Jamie Tanna
.
#blogumentation
#go
#web.
Simplifying Spring (Boot) ExceptionHandlers with ResponseStatus Annotations (2 mins read).
How to use annotations to drive HTTP response codes from a Spring ExceptionHandler.
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#spring.
Mocking void methods with Mockito (1 mins read).
How to Mock a void method with Mockito, for instance to throw an exception.
Content Negotiation with Servlet Filter in Spring (Boot) (3 mins read).
How to perform content-negotiation in a Servlet Filter, to serve the correct representation of error to a consumer, based on the Accept header.
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#spring
#content-negotiation.
Content Negotiation with ControllerAdvice and ExceptionHandlers in Spring (Boot) (5 mins read).
How to perform content-negotiation in a Spring ExceptionHandler, to serve the correct representation of error to a consumer, based on the Accept header.
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#spring
#content-negotiation.
Error Handling in (Spring) Servlet Filters (2 mins read).
How to return HTTP errors when a Java Servlet fails with Spring (Boot).
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#spring.
Validating UUIDs with Regular Expressions in Java (1 mins read).
How to validate UUIDs and UUIDv4s in Java with a regex.
Auditing with Spring Boot Actuator (9 mins read).
How to use Spring Boot Actuator for your audit and business event logging needs.
by Jamie Tanna
.
#blogumentation
#java
#spring-boot
#spring-security
#logs.
Returning a Value, or a Default, From a Java Optional (1 mins read).
How to replace imperative code with a functional style, when returning a default value for a Java Optional.
by Jamie Tanna
.
#blogumentation
#java.
Adding both an ObjectMapper and a YAMLMapper to Spring Boot (2 mins read).
How to have an ObjectMapper and a YAMLMapper coexisting in a Spring Boot project's bean dependencies.
by Jamie Tanna
.
#blogumentation
#java
#jackson
#spring-boot.
Testing Data Serialisation/Deserialization in Java (with Gson) (3 mins read).
How to validate your JSON types correctly serialise/deserialise when using the Gson library.
Improving Life-Work Balance on GitHub using per-Organisation Notification Settings (2 mins read).
How to set up per-organisation notification settings so your personal email doesn't get work-related notifications.
by Jamie Tanna
.
#blogumentation
#github
#life-work-balance.
Publishing to Maven Repositories with GitLab CI, with Signed Artefacts (4 mins read).
How to publish signed artefacts from a Gradle build to Maven repositories (such as Maven Central) when using GitLab CI.
by Jamie Tanna
.
#blogumentation
#gradle
#java
#gitlab-ci
#gpg.