问题
I'm a beginner in Python and Flask ecosystems, trying to create a small proof-of-concept Web application for a research project. I'm using Debian Linux 7.9, PostgreSQL 9.5, SQLAlchemy (latest) and Flask-AppBuilder (latest). Since creating models manually is tedious and error-prone, I searched the mighty Internet and discovered the flask-sqlacodegen project (note that this a fork of sqlacodegen with improved features for Flask users). I installed flask-sqlqcodegen from GitHub (cloned repo and then ran python setup.py install). However, when trying to use it to generate models, it produces an error, as follows:
> sqlacodegen postgresql+psycopg2://USER:PASS@HOST/DBNAME --flask
Traceback (most recent call last):
File "/usr/local/bin/sqlacodegen", line 9, in <module>
load_entry_point('sqlacodegen==1.1.5.pre2', 'console_scripts', 'sqlacodegen')()
File "/usr/local/lib/python2.7/dist-packages/sqlacodegen-1.1.5.pre2-py2.7.egg/sqlacodegen/main.py", line 57, in main
args.flask, fkcols)
File "/usr/local/lib/python2.7/dist-packages/sqlacodegen-1.1.5.pre2-py2.7.egg/sqlacodegen/codegen.py", line 597, in __init__
model = ModelClass(table, links[table.name], inflect_engine, not nojoined)
File "/usr/local/lib/python2.7/dist-packages/sqlacodegen-1.1.5.pre2-py2.7.egg/sqlacodegen/codegen.py", line 319, in __init__
relationship_ = ManyToOneRelationship(self.name, target_cls, constraint, inflect_engine)
File "/usr/local/lib/python2.7/dist-packages/sqlacodegen-1.1.5.pre2-py2.7.egg/sqlacodegen/codegen.py", line 455, in __init__
colname = constraint.columns[0]
File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/util/_collections.py", line 194, in __getitem__
return self._data[key]
KeyError: 0
What is going on? Any help will be much appreciated.
回答1:
Upon some Internet searching, I ran across an issue on GitHub, which described exactly the same problem. However, the most recent recommendation at the time produced another error instead of the original one. In the discussion with the author of flask-sqlcodegen, it appeared that there exist a pull request (PR) kindly provided by a project contributor that apparently should fix the problem. After updating my local repository, followed by rebuilding and reinstalling the software, I was able to successfully generate models for my database. The whole process consists of the following steps.
- Change to directory with a local repo of
flask-sqlcodegen. - If you made any changes, like I did, stash them:
git stash. - Update repo:
git pull origin master(now includes that PR). - Rebuild/install software:
python setup.py install. - If you need your prior changes, restore them:
git stash pop. Otherwise, discard them:git reset --hard. Change to your Flask application directory and auto-generate the models, as follows.
sqlacodegen --flask --outfile models.py postgresql+psycopg2://USER:PASS@HOST/DBNAME
Acknowledgements: Big thank you to Kamil Sindi (the flask-sqlcodegen's author) for the nice software and rapid & helpful feedback as well as to Alisdair Venn for that valuable pull request.
来源：https://stackoverflow.com/questions/38657634/generating-models-for-flask-appbuilder-using-flask-sqlqcodegen