Only read csv if the first 5 lines exist

Question

I have the following source code. I upload a csv file and write to a table in BigQuery. I need to include code that only that csv file can be saved in the table if there are 5 rows in the csv. If there are not 5 rows, stop the process.

code

    with open('/tmp/{}'.format(input_file), "r") as csvfile:
        lines = len(list(csvfile))-1
        csvfile.seek(0)
        reader = csv.reader(csvfile)
        for i, row in enumerate(reader):
            # add header 
            if add_header:
              if (i == 0):
                  header_value = row[0:]
              
              lst_csvfile.append(header_value)
              add_header = False
            
            # add rows
            if (i > 0):
              # transform cpf
              new_row = [trata_cpf(row[0]), row[1], row[2]]
              lst_csvfile.append(new_row)
    # write gcs
    db_data.to_csv('/tmp/{}'.format(input_file) ,index=False)
    gcs_upload('{}'.format(input_file), '/tmp/{}'.format(input_file), gcs_bucket_temp)
    print('Encrypt File DONE: {}'.format(input_file))

Answer 1

You have the right idea here using lines = len(list(csvfile))-1 to determine how many non-header lines (records) there are in the file. You can add a simple if statement to skip the loop or return from the method:

with open('/tmp/{}'.format(input_file), "r") as csvfile:
    lines = len(csvfile.readlines()) - 1

    csvfile.seek(0)
    reader = csv.reader(csvfile)

    if lines < 5:
        return  # assuming you do not want the last 3 lines to execute

    for i, row in enumerate(reader):
        # rest of code

if you need the final lines to execute wrap in an else statement:

    lines = len(csvfile.readlines()) - 1

    csvfile.seek(0)
    reader = csv.reader(csvfile)

    if lines >= 5:
        for i, row in enumerate(reader):
            # rest of code

    # write gcs
    db_data.to_csv('/tmp/{}'.format(input_file) ,index=False)
    gcs_upload('{}'.format(input_file), '/tmp/{}'.format(input_file), gcs_bucket_temp)
    print('Encrypt File DONE: {}'.format(input_file))