Develop Reference

using variable (f)-string stored in json

I have a json config file where I store my path to data there
The data is bucketed in month and days, so without the json I would use an f-string like:
spark.read.parquet(f"home/data/month={MONTH}/day={DAY}")
Now I want to extract that from json. However, I run into problems with the Month and day variable. I do not want to split the path in the json.
But writing it like this:
{
"path":"home/data/month={MONTH}/day={DAY}"
}
and loading with:
DAY="1"
MONTH="12"
conf_path=pandas.read_json("...")
path=conf_path["path"]
data=spark.read_parquet(f"{path}")
does not really work.
Could you hint me a solution to retrieving a path with variable elements and filling them after reading? How would you store the path or retrieve it without splitting the path? Thanks
------- EDIT: SOLUTION --------
Thanks to Deepak Tripathi answer below, the answer is to use string format.
with the code like this:
day="1"
month="12"
conf_path=pandas.read_json("...")
path=conf_path["path"]
data=spark.read_parquet(path.format(MONTH=month, DAY=day))

you should use string.format() instead of f-strings
Still if you want to use f-strings then you should use eval like this, its unsafe
DAY="1"
MONTH="12"
df = pd.DataFrame(
[{
"path":"home/data/month={MONTH}/day={DAY}"
},
{
"path":"home/data/month={MONTH}/day={DAY}"
}
]
)
a = df['path'][0]
print(eval(f"f'{a}'"))
#home/data/month=12/day=1

Python parsing json data

I have a json object saved inside test_data and I need to know if the string inside test_data['sign_in_info']['package_type'] contains the string "vacation_package" in it. I assumed that in could help but I'm not sure how to use it properly or if it´s correct to use it. This is an example of the json object:
"checkout_details": {
"file_name" : "pnc04",
"test_directory" : "test_pnc04_package_today3_signedout_noinsurance_cc",
"scope": "wdw",
"number_of_adults": "2",
"number_of_children": "0",
"sign_in_info": {
"should_login": false,
**"package_type": "vacation_package"**
},
package type has "vacation_package" in it, but it's not always this way.
For now I´m only saving the data this way:
package_type = test_data['sign_in_info']['package_type']
Now, is it ok to do something like:
p= "vacation_package"
if(p in package_type):
....
Or do I have to use 're' to cut the string and find it that way?

You answer depends on what exactly you expect to get from test_data['sign_in_info']['package_type']. Will 'vacation_package' always be by itself? Then in is fine. Could it be part of a larger string? Then you need to use re.search. It might be safer just to use re.search (and a good opportunity to practice regular expressions).

No need to use re, assuming you are using the json package. Yes, it's okay to do that, but are you trying to see if there is a "package type" listed, or if the package type contains vacation_package, possibly among other things? If not, this might be closer to what you want, as it checks for exact matches:
import json
data = json.load(open('file.json'))
if data['sign_in_info'].get('package_type') == "vacation_package":
pass # do something

How can I change urlencode to python dictionary

I have got data from POST like
first_name=jon&nick_name=harry
How can I change this to a python dictionary, like :
{
"first_name":"jon",
"nick_name":"harry"
}

>>> urlparse.parse_qs("first_name=jon&nick_name=harry")
{'nick_name': ['harry'], 'first_name': ['jon']}

If you trust that the URL arguments will always be properly formatted, this would be a minimal solution:
dict(pair.split("=") for pair in urlargs.split("&"))
In code that's going to be publicly accessible though, you'll probably want to use a library that does error checking. If you're using Django, you'll probably have access to them already in the dictionary-like object HttpRequest.POST.

Creating views in django (string indentation problems)

I am new to both Python (and django) - but not to programming.
I am having no end of problems with identation in my view. I am trying to generate my html dynamically, so that means a lot of string manipulation. Obviously - I cant have my entire HTML page in one line - so what is required in order to be able to dynamically build an html string, i.e. mixing strings and other variables?
For example, using PHP, the following trivial example demonstrates generating an HTML doc containing a table
<?php
$output = '<html><head><title>Getting worked up over Python indentations</title></head><body>';
output .= '<table><tbody>'
for($i=0; $i< 10; $i++){
output .= '<tr class="'.(($i%2) ? 'even' : 'odd').'"><td>Row: '.$i;
}
$output .= '</tbody></table></body></html>'
echo $output;
I am trying to do something similar in Python (in my views.py), and I get errors like:
EOL while scanning string literal (views.py, line 21)
When I put everything in a single line, it gets rid of the error.
Could someone show how the little php script above will be written in python?, so I can use that as a template to fix my view.
[Edit]
My python code looks something like this:
def just_frigging_doit(request):
html = '<html>
<head><title>What the funk<title></head>
<body>'
# try to start builing dynamic HTML from this point onward...
# but server barfs even further up, on the html var declaration line.
[Edit2]
I have added triple quotes like suggested by Ned and S.Lott, and that works fine if I want to print out static text. If I want to create dynamic html (for example a row number), I get an exception - cannot concatenate 'str' and 'int' objects.

I am trying to generate my html dynamically, so that means a lot of string manipulation.
Don't do this.
Use Django's templates. They work really, really well. If you can't figure out how to apply them, do this. Ask a question showing what you want to do. Don't ask how to make dynamic HTML. Ask about how to create whatever page feature you're trying to create. 80% of the time, a simple {%if%} or {%for%} does everything you need. The rest of the time you need to know how filters and the built-in tags work.
Use string.Template if you must fall back to "dynamic" HTML. http://docs.python.org/library/string.html#template-strings Once you try this, you'll find Django's is better.
Do not do string manipulation to create HTML.
cannot concatenate 'str' and 'int' objects.
Correct. You cannot.
You have three choices.
Convert the int to a string. Use the str() function. This doesn't scale well. You have lots of ad-hoc conversions and stuff. Unpleasant.
Use the format() method of a string to insert values into the string. This is slightly better than complex string manipulation. After doing this for a while, you figure out why templates are a good idea.
Use a template. You can try string.Template. After a while, you figure out why Django's are a good idea.
my_template.html
<html><head><title>Getting worked up over Python indentations</title></head><body>
<table><tbody>
{%for object in objects%}
<tr class="{%cycle 'even' 'odd'%}"><td>Row: {{object}}</td></tr>
{%endfor%}
</tbody></table></body></html>
views.py
def myview( request ):
render_to_response( 'my_template.html',
{ 'objects':range(10) }
)
I think that's all you'd need for a mockup.

In Python, a string can span lines if you use triple-quoting:
"""
This is a
multiline
string
"""
You probably want to use Django templates to create your HTML. Read a Django tutorial to see how it's done.
Python is strongly typed, meaning it won't automatically convert types for you to make your expressions work out, the way PHP will. So you can't concatenate strings and numbers like this: "hello" + num.

Django ajax formatting convention

What's the correct way to do an ajax request, I've seen people using a returning render_to_string so that they can do all their formatting within python using the template language. eg~
return render_to_string('calendar.html', {
'self' : self,
'month' : self.today.month,})
with this as the javascript:
$('#django_calendar_response').html(response)
But I've also seen people formatting their output within javascript using dom functions such as
return HttpResponse(serializers.serialize("json",
ilst, relations=('user',)), "application/json")
where the javascript is
items_display=function(items){
return LI(null,
A({'class':'userlink',
'href':'/url/user/'+items.fields.user.fields.name},
items.fields.user.fields.name),
is one of these correct and the other wrong? should I format my output in javascript or within python?

I've been using JSON exclusively for AJAX, with simplejson returning whatever data is really easy, it looks like this:
from django.utils import simplejson
reply = simplejson.dumps({'comment_body': formatted_post, 'user_icon': request.user.profile.image.url })
return HttpResponse(reply, mimetype="application/json")
and on the client side, with jquery's .post method handling a json reply is really easy too, you can specify json as your datatype:
$.post("/postcomment/", { body: comment_body },
function(data){
alert(data.comment_body)
}, "json");
I'm not saying this is the best solution, but it's proven to be very robust and easy to handle...
Hope this helps,
Martin

I do both. Sometimes I have short template snippets that I {% include %} in the big page template. It is often more DRY to render these and return the html to insert into the DOM (since the code is already set-up) than to have to write JS to do it (again). Other times, I just generate some JSON and inject that into the DOM.
Shortly, you can mix and match for the situation.