Flask & MongoDB - For Loop not working

Question

Having this for Flask:

example = mongo.db.example
got_name = example.find({'name':1})
got_lastname = example.find({'lastname':1})

details = {'name' : got_name, 'lastname' : got_lastname}

return render_template('blabla.html', details=details)

Then the for loop using Jinja in my HTML (wanting it to be a table):

{% for x in details}
<tr>
    <td>{{ x.['name'] }}</td>
    <td>{{ x.['lastname'] }}</td>
</tr>
{% endfor %}

But it won't work, it doesn't display anything in my table. I wrote this example above now, but my code is similar.

chridam · Accepted Answer · 2017-01-19 12:36:46Z

2

You may want to use find_one() instead of find() which returns a cursor to the documents which match the criteria. find_one() returns a single document which can then be used in the dictionary, instead of a cursor:

example = mongo.db.example
doc = example.find_one()

details = { 'name' : doc['name'], 'lastname' : doc['lastname'] }

return render_template('blabla.html', details=details)

Or

example = mongo.db.example
details = example.find_one({}, {'name':1, 'lastname':1})

return render_template('blabla.html', details=details)

And your template will be

<tr>
    <td>{{ details['name'] }}</td>
    <td>{{ details['lastname'] }}</td>
</tr>

If you want to iterate the whole collection and return a list if documents with just the name and lastname fields, then you should use the find() method. If you have a relatively small dataset, the following code will convert the entire result set (Cursor) into a list (everything is pulled into memory):

example = mongo.db.example
details = list(example.find({}, {'name': 1, 'lastname': 1}))

return render_template('blabla.html', details=details)

Then iterate the list in your template

{% for doc in details}
<tr>
    <td>{{ doc['name'] }}</td>
    <td>{{ doc['lastname'] }}</td>
</tr>
{% endfor %}

edited Jan 19, 2017 at 12:36

answered Jan 19, 2017 at 10:42

chridam

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5 Comments

nori Over a year ago

Everything works fine, but then I tried to iterate using your method. I've details = list(bans.find({}, {'Nume codat' : 1, 'SteamID' : 1, 'Motiv' : 1})), then <td>{{ x.['Nume codat'] }}</td> but I get „TemplateSyntaxError: expected name or number” @ <td>{{ x.['Nume codat'] }}</td>. Thanks for the reply, though!

nori Over a year ago

Weird, works if I delete the dot, ex. {{ x.['bla'] }} was wrong, but {{ x['blabla'] }} works. Should it work or was something done wrong by your side?

chridam Over a year ago

My bad, that was a typo on your part I failed to correct in giving my answer. I have updated the answer to reflect the correct approach.

nori Over a year ago

One more question: how do I make it so the first display is actually the last data that was inserted into the database? Cause if I insert some data now, it'll actually display at the bottom, after the other data. I want it to be inversed, hope you catch my drift.

chridam Over a year ago

You can try sort on the _id key (if your documents' _id key is an ObjectId) as details = list(example.find({}, {'name': 1, 'lastname': 1}).sort('_id', -1))

Vasili Syrakis · Accepted Answer · 2017-01-19 10:19:56Z

0

Your template would actually have to be more like this:

<tr>
    <td>{{ details['name'] }}</td>
    <td>{{ details['lastname'] }}</td>
</tr>

No loops.

If you had an array of dictionaries, then you could use your initial template.

answered Jan 19, 2017 at 10:19

Vasili Syrakis

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