how to convert request.args from string to list?

Question

I have such url:

http://0.0.0.0:5000/test?id=00000&coords=[55.530974,37.522081]

And there is some part of the code:

id = request.args.get('id')
 >'00000'

coords = request.args.get('coords')
> '[55.530974,37.522081]'

I need to get coords not like a string, but like a list [55.530974,37.522081]

Is there solution to convert it? Or make in another way?

Thanks a lot

`ast.literal_eval(coords)` So `ast.literal_eval('[55.530974,37.522081]')` will return `[55.530974, 37.522081]` — It_is_Chris, Jul 22 '21 at 13:43
Is `coords` always size 2? Would it be easier to pass something like `x_coord` + `y_coord`? — 0x5453, Jul 22 '21 at 13:44
Please never use an eval function with input from a url, it's a disaster waiting to happen — Simon Martineau, Jul 22 '21 at 13:44
@Ram Using `eval` is extremely insecure, and using it in this context would open up a huge vulnerability — Wondercricket, Jul 22 '21 at 13:48
@Wondercricket I am not aware of that. Could you explain why is that? — Ram, Jul 22 '21 at 13:53
@Ram There are many articles on that. [Here](https://stackoverflow.com/questions/661084/security-of-pythons-eval-on-untrusted-strings) is one to start — Wondercricket, Jul 22 '21 at 13:56
@Wondercricket It really is INSECURE. Thanks for letting me know. — Ram, Jul 22 '21 at 13:58

score 0 · Answer 1 · answered Jul 22 '21 at 13:47

0

Try:

>>> [float(n) for n in coords[1:-1].split(",")]
[55.530974, 37.522081]

Slice from [1:-1] to ignore the []

answered Jul 22 '21 at 13:47

not_speshal

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score 0 · Answer 2 · answered Jul 22 '21 at 13:49

The server receives the coords from a url, outside of the python runtime. Because of this, it will always come in as a string. The only was is to parse the string into an array of floats. You can either:

Split the coords query parameter into two different ones, individually parse them as floats and then assemble them into an array
Create a function that parses the array

I would recommend the first one; it is very common to send coordinates like this: ?long=1.11&lat=2.22

score 0 · Answer 3 · answered Jul 22 '21 at 13:53

0

Do some string manipulations like strip() and split() and convert it into a list.

coords = '[55.530974, 37.522081]'

coords = coords.strip('[')
coords = coords.strip(']')
l = list(map(float, coords.split(',')))
print(l)

[55.530974, 37.522081]

answered Jul 22 '21 at 13:53

Ram

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score 0 · Answer 4 · answered Jul 22 '21 at 13:53

If you do not have the possibility to change how the http request is made, and you are sure that the passed coordinates are always separated by a comma and you have curly brackets at the ends, then you can convert the string to a list in the following way

coords = request.args.get("coords").strip()[1:-1].split(",")

how to convert request.args from string to list?

4 Answers4