The single responsibility principle

Today, I added a new feature to a project that allows a member to search for a node based on either its title or a specified field on that node, select a result from an autocomplete list and then be redirected to their selected node.

I’ve already implemented this for other node types but needed to do the same for this node type.

There are some differences, such as the node type to query for; the additional field depends on which node type as does the text shown in the autocomplete list.

To do this, I needed to add a custom block and form, update the AutocompleteController, create a new instance of a NodeQuery class (a custom class within the custom module), register it as a service and update the SearchQueryFactory class.

A principle that I follow as much as possible is the single responsibility principle, or SRP (the ‘S’ in SOLID), where each function or class only has one responsibility - such as returning a response for the autocomplete list, determining the correct node query to use based on the search being run or building the query itself - these are separated and split into their own files.

Although more files and functions are created when coding in this way, though they are smaller and more straightforward to work with - which makes them easier to read, debug and maintain. It also makes code like the node query classes reusable as they aren’t embedded within a larger class and are easier to test.

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