Generate Database Diagram from Django Models¶
Database diagram are very useful project documentation. They might be useful for understanding the project. With projects under development, documentation, diagrams are not exception, easily gets out of sync with actual implementation. Generating documentation from code helps to keep the documentation always up to date with the current code.
Install django-extensions¶
Add django-extensions and pydotplus to requirements.txt:
requirements.txt¶
# ...
django-extensions
pydotplus
# ...
And run pip to apply the changes:
$ pip install -U -r requirements.txt
...
Register django_extensions application in settings.py:
elearn/settings.py¶
1INSTALLED_APPS = [
2 # ...
3 # 3rd party apps
4 'drf_yasg',
5 'django_extensions',
6 # Local apps
7 'courses',
8]
Examine the command options:
$ python elearn\manage.py graph_models --help
usage: manage.py graph_models [-h]
[--pygraphviz] [--pydot] [--dot] [--json] [--disable-fields]
[--disable-abstract-fields] [--group-models] [--all-applications]
[--output OUTPUTFILE] [--layout LAYOUT] [--theme THEME]
[--verbose-names] [--language LANGUAGE]
[--exclude-columns EXCLUDE_COLUMNS] [--exclude-models EXCLUDE_MODELS]
[--include-models INCLUDE_MODELS] [--inheritance] [--no-inheritance]
[--hide-relations-from-fields]
[--relation-fields-only RELATION_FIELDS_ONLY] [--disable-sort-fields]
[--hide-edge-labels]
[--arrow-shape {box,crow,curve,icurve,diamond,dot,inv,none,normal,tee,vee}]
[--color-code-deletions] [--rankdir {TB,BT,LR,RL}] [--version]
[-v {0,1,2,3}] [--settings SETTINGS] [--pythonpath PYTHONPATH]
[--traceback] [--no-color] [--force-color] [--skip-checks]
[app_label ...]
Creates a GraphViz dot file for the specified app names. You can pass multiple app names and they
will all be combined into a single model. Output is usually directed to a dot file.
positional arguments:
app_label
options:
-h, --help show this help message and exit
--pygraphviz Output graph data as image using PyGraphViz.
--pydot Output graph data as image using PyDot(Plus).
--dot Output graph data as raw DOT (graph description language) text data.
--json Output graph data as JSON
--disable-fields, -d Do not show the class member fields
--disable-abstract-fields
Do not show the class member fields that were inherited
--group-models, -g Group models together respective to their application
--all-applications, -a
Automatically include all applications from INSTALLED_APPS
--output OUTPUTFILE, -o OUTPUTFILE
Render output file. Type of output dependend on file extensions. Use png or
jpg to render graph to image.
--layout LAYOUT, -l LAYOUT
Layout to be used by GraphViz for visualization. Layouts: circo dot fdp
neato nop nop1 nop2 twopi
--theme THEME, -t THEME
Theme to use. Supplied are 'original' and 'django2018'. You can create your
own by creating dot templates in 'django_extentions/graph_models/themename/'
template directory.
--verbose-names, -n Use verbose_name of models and fields
--language LANGUAGE, -L LANGUAGE
Specify language used for verbose_name localization
--exclude-columns EXCLUDE_COLUMNS, -x EXCLUDE_COLUMNS
Exclude specific column(s) from the graph. Can also load exclude list from
file.
--exclude-models EXCLUDE_MODELS, -X EXCLUDE_MODELS
Exclude specific model(s) from the graph. Can also load exclude list from
file. Wildcards (*) are allowed.
--include-models INCLUDE_MODELS, -I INCLUDE_MODELS
Restrict the graph to specified models. Wildcards (*) are allowed.
--inheritance, -e Include inheritance arrows (default)
--no-inheritance, -E Do not include inheritance arrows
--hide-relations-from-fields, -R
Do not show relations as fields in the graph.
--relation-fields-only RELATION_FIELDS_ONLY
Only display fields that are relevant for relations
--disable-sort-fields, -S
Do not sort fields
--hide-edge-labels Do not show relations labels in the graph.
--arrow-shape {box,crow,curve,icurve,diamond,dot,inv,none,normal,tee,vee}
Arrow shape to use for relations. Default is dot. Available shapes: box,
crow, curve, icurve, diamond, dot, inv, none, normal, tee, vee.
--color-code-deletions
Color the relations according to their on_delete setting, where it it
applicable. The colors are: red (CASCADE), orange (SET_NULL), green
(SET_DEFAULT), yellow (SET), blue (PROTECT), grey (DO_NOTHING) and purple
(RESTRICT).
--rankdir {TB,BT,LR,RL}
Set direction of graph layout. Supported directions: "TB", "LR", "BT", "RL",
corresponding to directed graphs drawn from top to bottom, from left to
right, from bottom to top, and from right to left, respectively. Default is
TB.
--version Show program's version number and exit.
-v {0,1,2,3}, --verbosity {0,1,2,3}
Verbosity level; 0=minimal output, 1=normal output, 2=verbose output, 3=very
verbose output
--settings SETTINGS The Python path to a settings module, e.g. "myproject.settings.main". If
this isn't provided, the DJANGO_SETTINGS_MODULE environment variable will be
used.
--pythonpath PYTHONPATH
A directory to add to the Python path, e.g.
"/home/djangoprojects/myproject".
--traceback Raise on CommandError exceptions.
--no-color Don't colorize the command output.
--force-color Force colorization of the command output.
--skip-checks Skip system checks.
Install Robot Font on Windows¶
Download from Google fonts.
Extract the zip package.
Select all the font files, right click and select Install from the menu.
Generate ER Model Diagram for All Applications¶
$ python elearn/manage.py graph_models -a -g -o elearn_full_erd.png
The -a switch is used to generate ER diagram for all models. The -g switch is grouping models visually by application.
Generate Database Diagram for One or More Applications¶
To generate model only for a single application, e.g. courses:
$ python elearn/manage.py graph_models -o elearn_courses_erd.png courses
One could generate ER diagram even for Django’s core application’s models:
Generate Database Diagram for Specific Models¶
$ python elearn/manage.py graph_models --pygraphviz -o elearn_course_models_erd.png courses -I Course,Module,Subject,Content
Same result could be achieved specifying models for all the applications:
$ python elearn/manage.py graph_models --pygraphviz -o elearn_course_models_erd.png -a -I Course,Module,Subject,Content
Install PyGraphViz on Windows¶
Install Graphviz for your system.
Install phygraphviz:
$ pip install --global-option=build_ext --global-option="-IC:\Program Files\Graphviz\include" --global-option="-LC:\Program Files\Graphviz\lib" pygraphviz
...
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