Last activity on 12 December 2020
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composer require mcstreetguy/fusion-debugger

A debugger plugin for Neos.Fusion.


A debugger plugin for Neos.Fusion.

Release Date
23.12.2020 13:01:50
Requires (dev)
MIT 283a9d382ca25612c751f85751653a95c8063d5b


A small plugin for the awesome Neos CMS, to improve debugging of Fusion DSL code.

Table of Contents


What is this plugin capable of?

  • Debugging fully merged Fusion prototype definitions
  • Visualizing (parts of) the combined Fusion object tree
  • Linting Fusion files for syntax errors

Why do I need it?

Did you ever came across some really strange rending issue while you created a page in Neos? And did you ever told yourself: "Why the actual hell is this happening? It's supposed to do something different."
Well then you probably know about the reasons behind this plugin, it's improved debugging.

It's currently not possible in common Neos installations to have a closer look behind the scenes of Fusion rendering. It parses some code, does some magic and then hopefully your expected result will appear. But what happens actually in between?
To get rid of that uncertainty this Plugin allows you to visualize what you normally won't see: the merged Fusion prototype configuration and the combined object tree.


Install the plugin by requiring it through composer:

composer require --dev mcstreetguy/fusion-debugger

If composer refuses to install the plugin, try requiring a specific version of it. The major version of this project will always work with the corresponding Neos release.

composer require --dev mcstreetguy/fusion-debugger:^7.0   # for Neos v7.x
composer require --dev mcstreetguy/fusion-debugger:^5.0   # for Neos v5.x
composer require --dev mcstreetguy/fusion-debugger:^4.0   # for Neos v4.x
composer require --dev mcstreetguy/fusion-debugger:^3.0   # for Neos v3.x

We support all Neos versions ranging from 3.0 up to 7.0 officially. For any other version you may encounter unexpected issues and there is no guarantee that the debugger will work properly! (Even though we kind of support Neos v2.3, see below for more information.)

Usage outside of Neos

As the plugin only relies on neos/flow and neos/fusion as dependencies, you can actually use it outside of Neos projects as long as both required components are available. Testing this is currently an ongoing process, but any feedback on compatibility outside Neos is greatly appreciated. If you come across any issues not covered in the troubleshooting section below, please report them.


Invalid controller class name "". Make sure your controller is in a folder named "Command" and it's name ends in "CommandController"

This error happens only straight after installing the plugin as this corrupts the internal code caches of Flow in some way.
We couldn't locate the origin of this problem yet but hope to resolve it asap! Until then we recommend force-clearing the application caches after requiring the plugin through composer, as the automatic graceful clear during the installation is what probably causes this problem to arise.

/path/to/flow flow:cache:flush --force

In some edge cases it might happen that the entire Flow CLI stops working upon installation. In that case you are required to manually empty the corresponding Data/Temporary directory, that will get Flow running again. If you are uncertain which directories to remove, you may also delete the entire directory at once, causing Flow to regenerate it fully.

Support for older Neos / PHP

The plugin normally is written vor Neos v3.3 and above and in addition makes extensive use of PHP7.1 features. To make the functionality available for Neos v3.0-v3.2 and also for older PHP versions like 7.0 and 5.6 the plugin has been backported. In that version all type hinting has been replaced by assertions and the composer requirements have been adapted.

To install the backported version you may also require it through composer:

composer require --dev mcstreetguy/fusion-debugger:dev-backport

Please not that this backported version will not be tagged accordingly. The backport branch will be kept up with the master as much as possible to provide you latest features, but we cannot guarantee that this will happen simultaneously.



The plugin provides several commands to the Flow CLI. These are listed below for reference. Please see the respective help pages for more detailled information.


mcstreetguy.fusiondebugger:fusion:debugprototype [--no-color] [--no-flatten] <prototype>

Reads the definition of the requested prototype from the __prototypes key in the parsed object tree and resolves the contained prototype chain very carefully so that the result contains all properties, either inherited or explictely defined. For better readability, this command also includes something similar to syntax highlighting as several parts of the built tree are colored (such as eel expressions, further prototype names or just plain strings). Furthermore it flattens the resulting data by removing empty properties and combining the internal properties for e.g. plain values (as these are stored with three properties but could be displayed directly without an array structure). These additional behaviour can be suppressed by specifying the options --no-color or --no-flatten if it corrupts the resulting data or your terminal does not support ANSI colors.


mcstreetguy.fusiondebugger:fusion:showobjecttree [--path <path>]

Builds the object tree from all Fusion files and displays it in an ASCII tree structure (excluding the __prototypes key as we got the above command for that). You can optionally provide a dot-separated path that will be loaded instead of the whole tree. (e.g. ./flow fusion:showobjecttree --path


mcstreetguy.fusiondebugger:fusion:lint [--package-key <packageKey>] [--verbose] [--quiet]

Checks all Fusion files individually for syntax errors and lists the incorrect files with their associated package and file path. This command was intended to programmatically check the correctness of the Fusion source code and is in fact still an experiment but listed for the sake of completeness.


mcstreetguy.fusiondebugger:fusion:listprototypes [--no-format]

Lists all known Fusion prototype names.
If the --no-format option is specified, the list will lack any bullets and return unsorted.


The plugin comes with minimal configuration options available. These are listed below for reference.


An array of file path patterns used to search for Fusion files that will be loaded.
The default path resource://@package/Private/Fusion/ is already present for ease of use. If your setup involves Fusion files at other locations as the default one provide these here.

The following placeholders can be used inside the pattern and will be exchanged with real values upon evaluation:

Placeholder Description
@package The current package key from where the fusion gets loaded.


We use SemVer for versioning. For the versions available, see the tags on this repository.


See also the list of contributors who participated in this project.


This project is licensed under the MIT License - see the LICENSE file for details

The content of the readme is provided by Github