Upload a CSV file in Fastapi and convert it into Json format-CodePudding

I am trying to convert my CSV file to Json using by uploading it into Fastapi first but when I try to process it directly (without storing it somewhere) I get error

Error : FileNotFoundError: [Error 2] No such file or directory : "testdata.csv"

Code :

async def upload(file: UploadFile = File(...)):
    data = {}    
    with open(file.filename,encoding='utf-8') as csvf:
        csvReader = csv.DictReader(csvf)
        for rows in csvReader:             
            key = rows['No']
            data[key] = rows    
    return {data}```

CodePudding user response：

The reason why you are getting the Error : FileNotFoundError: [Error 2] No such file or directory : "testdata.csv" is because you are trying to read a file that is not stored locally.

If you want to read the file this way you should save the uploaded file before proceeding:

async def upload(uploaded_file: UploadFile = File(...)):
    # save csv to local dir
    csv_name = uploaded_file.filename
    csv_path = 'path_to/csv_dir/'
    file_path = os.path.join(csv_path, csv_name)
    with open(file_path, mode='wb ') as f:
        f.write(uploaded_file.file.read())

    # read csv and convert to json
    data = {}
    with open(file_path, mode='r', encoding='utf-8') as csvf:
        csvReader = csv.DictReader(csvf)
        for rows in csvReader:             
            key = rows['No']
            data[key] = rows    
    return {data}

CodePudding user response：

The file in the async function upload() is already open and you can fetch characters from it directly, there's no need to open it again. Also in FastAPI the class UploadFile is actually derived from standard library tempfile.SpooledTemporaryFile, which cannot be accessed by specifying path of the temporary file.

For example , if you use CPython and read the value of file.filename in the upload() in the Unix-like system, it returns a number instead of a well-formed path, because any instance of the class SpooledTemporaryFile will create a file descriptor (at some point when current stored data exceeds max_size) and simply return the file descriptor (should be a number in Unix) on accessing SpooledTemporaryFile.filename