A debugger plugin for Neos.Fusion.

0.6-alpha 2019-08-21 12:19 UTC


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

PLEASE NOTE! This plugin is currently work in progress and alls of it's parts are subject to change probably! You should not rely on this in a production environment yet as it is not proven to be stable!

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


Could not find a version of package mcstreetguy/fusion-debugger matching your minimum-stability

Please make sure that your minimum-stability is at least set to alpha as this package has no stable release yet. Alternatively you could require the package with an explicit alpha-version constraint, but please note that this will only work for root-level manifests:

composer require --dev mcstreetguy/fusion-debugger:@alpha



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] [--not-flat] <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 --not-flat if it corrupts the resulting data or your terminal does not support ANSI colors. If you have namespace mappings defined in MCStreetguy.FusionDebugger.namespaceMap, these will be resolved before loading the prototype.


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.


An associative array of fusion namespace shorthands to full namespaces mappings. By default, no namespace is set as this varies widely and depends on the current use case. If you define namespace mappings here, these will be taken into account for the fusion:debugprototype command.

Namespace Map Example
      'N': 'Neos.Neos'
      'F': 'Neos.Fusion'


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