Mongoid-ERD

Create model-diagram (ERD graph) via Graphviz using the mongoid’s model source code.

Export a executable merd:

$ merd | dot -Tpng > docs/erd.png

or:

$ merd --model_dir=other/models | dot -Tpng > docs/erd.png

You can also create only a subset of models by:

$ merd --include=Class1,Class2

or 

$ merd --exclude=Class4,Class5

You need to add dot executable in your PATH.

Class, Inherits and Fields

  • class xxx:yyy: a record xxx inherit from yyy. The first class that contains include Mongoid::Document on the file will be tracked. yyy will be created as a box node if no corresponding file found.

  • field :xxx, type:yyy: a field xxx with type yyy. type and default will be tracked.

  • embeds_many/embeds_one/has_many/has_one :xxx, :as => :yyy: field and a belong_to/embeds_many/embeds_one/has_one link to xxx

  • belongs_to/embedded_in :xxx: a field without link.

Methods before :private keyword will also be tracked.

Special Markers

erd_tag user.core tag name of the current class (see configuration files below)

erd{}

class xxx:yyy # erd{fillcolor:xxx} yyy: yyy will become the label of the current class.

field ... # erd{...} xxx: xxx will become the label of that field.

embeds_many ... # erd{...} yyy: yyy will become the label of that edge.

erd -> node_name{color:yyy} label: arbitrage edge with attributes.

Configuration Files

config/mongoid_erd.yml:

user: {shape: Mrecord}
user.core: {fillcolor: blue}

user.core attributes will be merged to user, then should be merged into class ... # erd{attrs}. Those attributes will passed to dot language as the attributes associate to the class node.

An other will to use tag is restrict output contains only classes with specific tag:

$ merd --tag=user