英文:
Flask TypeError: Expected bytes
问题
我正在尝试从表格中获取数据并响应结果。我遇到了这个问题，因为数据来自数据库。以下是代码：
cursor = connection.cursor()
cursor.execute("select * from table")
result = cursor.fetchall()
for row in result:
data = row
connection.close()
return Response(
data,
mimetype="text/csv",
headers={
"Content-disposition": "attachment; filename=data.csv"
},
)
在尝试获取数据时，我遇到了这个错误：
TypeError: 期望的是字节
我该如何解决这个问题？
英文:
I'm trying to get data from a table and response the result. I am facing this issue since the data is from a database. Below is the code:
cursor = connection.cursor()
cursor.execute("""select * from table""")
result = cursor.fetchall()
for row in result:
data = row
connection.close()
return Response(
data,
mimetype="text/csv",
headers={
"Content-disposition": "attachment; filename=data.csv"
},
)
While trying to get it, I am getting this error:
TypeError: Expected bytes
How can I resolve this?
答案1
得分: 1
以下是翻译好的代码部分，不包括翻译请求的内容：
import csv
from io import StringIO
# ...
# 实例化一个StringIO来在内存中缓冲CSV
sio = StringIO()
# 实例化一个CSV写入器来写入StringIO
cw = csv.writer(sio)
# 执行查询
cursor.execute("""select * from table""")
# 根据您的数据库，您可以在循环之前使用 `cw.writerow`
# 来将列名作为第一行写入CSV。
# 循环遍历查询返回的行，将每个单元格转换为字符串后写入CSV写入器。
# 您可能需要调整 `str()` 调用以特定方式格式化日期等内容。
for row in cursor:
cw.writerow([str(cell) for cell in row])
# 获取StringIO的内容并编码为UTF-8字节
csv_bytes = sio.getvalue().encode("utf-8")
return Response(
csv_bytes,
mimetype="text/csv",
headers={
"Content-disposition": "attachment; filename=data.csv"
},
)
英文:
You're probably looking for something like this. I elided the connection-related bits, because they're specific to your database connection.
import csv
from io import StringIO
# ...
# Instantiate a StringIO to buffer the CSV in memory to
sio = StringIO()
# Instantiate a CSV writer to write to the StringIO
cw = csv.writer(sio)
# Execute the query
cursor.execute("""select * from table""")
# Depending on your database, you could use `cw.writerow`
# before the loop to write the column names as the first line here.
# Loop over the rows returned by the query, casting each cell to a string
# before writing to the CSV writer. You may need to adjust the `str()`
# invocation to format e.g. dates in a specific way.
for row in cursor:
cw.writerow([str(cell) for cell in row])
# Get the StringIO's contents and encode to UTF-8 bytes
csv_bytes = sio.getvalue().encode("utf-8")
return Response(
csv_bytes,
mimetype="text/csv",
headers={
"Content-disposition": "attachment; filename=data.csv"
},
)
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