In a new post to his site Rob Allen shows you how to implement CORS in a Zend Expressive application through the use of a simple middleware wrapper that sends the appropriate headers.

On a recent project, I needed to implement CORS support for my Expressive API. The easiest way to do this is to use Mike Tuupola's PSR-7 CORS Middleware.

As this is a standard Slim-Style PSR-7 middleware implementation, we need to wrap it for Expressive, so we make a factory. [...] We then register this in our AppConfigProvider::getDependencies() by adding to the factories key.

He includes the code and configuration changes required to make it all work and includes example output of a request (with headers) from a curl call to the API. He also includes a section on working with JSON error responses and ProblemDetails for when there are issues related to the current CORS policy definition.

The Zend Framework blog has a new tutorial posted by Matthew Weier O'Phinney covering error handling techniques in Expressive with a few examples making use of some custom middleware and logic.

One of the big improvements in Expressive 2 is how error handling is approached. While the error handling documentation covers the feature in detail, more examples are never a bad thing!

In their example they're creating an API resource that returns a list of book details (ones the user has read). The goal is to use the existing error handling for everything except the custom exceptions they want to throw but keep with the JSON handling throughout. First the middleware to handling the API request is shown, complete with sorting and pagination. Then come the custom exception examples for invalid requests and server issues. These exceptions are then put into the Problem Details format with the help of another middleware. This then all tied together with the nested middleware handling Expressive provides and an example of the end result is included.