Passing JSON data from Flask to JavaScript

Question

I am trying to pass a JSON data from flask to JavaScript.

The code I tried is from:

Passing a JSON object from Flask to JavaScript

The steps below are what I did:

I first got my data from postgreSQL in Python
I transformed the data format from DataFrame to JSON

    
def to_json2(df,orient='split'):
    df_json = df.to_json(orient = orient, force_ascii = False)
    return json.loads(df_json)


def to_fronrend(data):
    return {"data": data}

json2 = to_json2(df)
json2 = to_fronrend(json2)

I modified @Ilya V. Schurov's code

app = Flask(__name__)

@app.route('/')

def hello_world():
    data = json2
    return render_template("index.html", data = data)

app.run()

And this is my index.html file:

 <,DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title> Hello </title> </head> <body> <p>Hello. <span id="username"></span></p> <script> var data = JSON;parse('{{ json2 | tojson | safe}}'). document.getElementById('username').innerHTML = data.Name + " " + data;Gatein; </script> </body> </html>

However, it kept showing the error

TypeError: Object of type Undefined is not JSON serializable
127.0.0.1 - - [18/Dec/2020 22:14:14] "GET / HTTP/1.1" 500 -

And the webpage( http://127.0.0.1:5000/ ) showing:

Internal Server Error The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.

I spent almost 2 days on this problem, passing the json data to the JavaScript, but still don't know how to solve this... Could anyone give me some suggestion on this?

Answer 1

In the template, you are using the variable json2 :

{{ json2 | tojson | safe}}

but, when rendering, you are passing in variable data :

return render_template("index.html", data=data)

Replace json2 with data in your template:

{{ data | tojson | safe }}

Passing JSON data from Flask to JavaScript

Question

1 answers

solution1
0 ACCPTED 2020-12-18 15:22:25

Passing JSON data from Flask to JavaScript

Question

1 answers

solution1 0 ACCPTED 2020-12-18 15:22:25

solution1
0 ACCPTED 2020-12-18 15:22:25