Passing a list from peewee to jinja2 in flask

Question

I'm trying to write a Flask application that queries my database (using peewee), and sends the results into Jinja2 for rendering. My view looks like this:

@application.route('/maindash')
def maindash():
    sq = Selfreported.select().join(Demog).where(Demog.mrn == session['mrn']).order_by(Selfreported.reportingdate)
    series1data = ["Series 1", ([s.reportingdate, s.series] for s in sq)]
    jsonedData = json.dumps(series1data)

    return render_template('maindash.html', seriesdata=jsonedData)

To pass the results from the query into Jinja2, I know that I need to serialize the data. But when I call json.dumps: TypeError: at 0x104854be0> is not JSON serializable. So I guess I am not actually getting the data, but trying to serialize the query object itself?

Every peewee example I've looked at uses the object_list helper function from peewee-flask, rather than passing query results straight into render_template. I've looked at object_list, but I'm having a hard time understanding it --

def object_list(template_name, qr, var_name='object_list', **kwargs):
kwargs.update(
    page=int(request.args.get('page', 1)),
    pages=qr.count() / 20 + 1
)
kwargs[var_name] = qr.paginate(kwargs['page'])
return render_template(template_name, **kwargs)

Is there a method on a QueryResultWrapper I should be using to get the actual data rather than objects? I've looked at tuples() and dict(), but I couldn't iterate over them.

score 4 · Accepted Answer · answered Apr 15 '13 at 22:50

There is no reason to serialize the data before passing it to Jinja as Jinja is written in Python and can handle anything that Flask can handle. Simply pass series1data into your render_template call and walk over it in your template:

return render_template('maindash.html', seriesdata=series1data)

{# maindash.html #}
{% for reportingdate, series in seriesdata[1] %}
    {{ reportingdate }} - {{ series }}<br>
{% endfor %}

Passing a list from peewee to jinja2 in flask

1 Answers1