Flask get a multi-dimensional array posted to it as an array

user_14238901 0
Viewed 555

Note: Using Flask & Reactjs

I'm currently struggling with a bug where I'm posting a 3-d array from my frontend to my backend and I'm trying to retrieve it using request.form.get('array',type=list), but it ends up being recieved as a 1d array.

Frontend:

let data = new FormData();
this.array = [[[1,4],[2,4]],[[3,1],[2,4]],[[7,4],[1,1]]]
data.append("array", this.array);
return axios
      .post(this.url+`/post_arr`, data, {
        headers: {
          "Content-Type": "multipart/form-data",
        },
      })
      .then((res) => {console.log('hi')
        })
        
      })  }

backend:

@app.route('/post_arr',methods=['POST'])
def test():
print(request.form.get('array',type=list))
>['1','4','2','4','3','1','2','4','7','4','1','1']

Rather than retrieving the array as a 3-d array, it retrieves it as a flattened 1d array, which is not ideal. Is there a way to solve this?

reactjs stringify flask http python
1 Answers

When you append a multidimensional array to the javascript formData object, it will get automatically transformed into a flattened string.

What you need in javascript is:

let data = new FormData();
this.array = [[[1,4],[2,4]],[[3,1],[2,4]],[[7,4],[1,1]]];
data.append("array", JSON.stringify(array));

Then in flask:

The getlist method is what you're looking for.

Try the following:

array = request.form.getlist('array')

if it returns in a string like this ['[[[1,4],[2,4]],[[3,1],[2,4]],[[7,4],[1,1]]]'], simply get the list using the first index: array[0]

should return

[[[1,4],[2,4]],[[3,1],[2,4]],[[7,4],[1,1]]]
user_139912190
Related