Python ValueError: dict 包含不在字段名中的字段
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ValueError: dict contains fields not in fieldnames
提问by akbsmile
Can someone help me with this.
有人可以帮我弄这个吗。
I have my Select query
我有我的选择查询
selectAttendance = """SELECT * FROM table """
And I want the content of my select query and include a header when I download the csv file, So I did this query:
我想要我的选择查询的内容并在下载 csv 文件时包含一个标题，所以我做了这个查询：
with open(os.path.join(current_app.config['UPLOAD_FOLDER'], 'csv.csv'), 'wb') as csvfile:
writer = csv.DictWriter(csvfile,fieldnames = ["Bio_Id","Last_Name","First_Name","late","undertime","total_minutes", "total_ot", "total_nsd", "total_absences"], delimiter = ';')
writer.writeheader()
writer.writerow(db.session.execute(selectAttendance))
db.session.commit()
but it gives me this error
但它给了我这个错误
**ValueError: dict contains fields not in fieldnames**
I want to have like this output in my downloaded csv file:
我想在我下载的 csv 文件中有这样的输出：
Bio_Id Last_Name First_Name late undertime total_minutes total_ot total_nsd total_absences
1 Joe Spark 1 1 2 1 1 1
Thank you in advance.
先感谢您。
采纳答案by bgusach
As the error states: the dictionary that comes from the query contains more key than the field names you specified in the DictWriter constructor.
正如错误所述：来自查询的字典包含的键比您在 DictWriter 构造函数中指定的字段名称多。
One solution would be to filter that in advance, something like this:
一种解决方案是提前过滤，如下所示：
field_names = ["Bio_Id","Last_Name", ...]
writer = csv.DictWriter(csvfile,fieldnames=field_names , delimiter = ';')
writer.writeheader()
data = {key: value for key, value in db.session.execute(selectAttendance).items()
if key in field_names}
writer.writerow(data)
Another solution could be to construct the query using only those fields:
另一种解决方案可能是仅使用这些字段构建查询：
query = 'SELECT %s FROM table' % ', '.join(field_names)
However, Tim Pietzcker's answer is the best.
然而，Tim Pietzcker 的回答是最好的。
回答by Tim Pietzcker
As the error message clearly states, your dictionary contains keys that don't have a corresponding entry in your fieldnamesparameter. Assuming that these are just extra fields, you can ignore them by using the extrasactionparameter during construction of your DictWriterobject:
正如错误消息明确指出的那样，您的字典包含在您的fieldnames参数中没有相应条目的键。假设这些只是额外的字段，您可以通过extrasaction在构造DictWriter对象期间使用参数来忽略它们：
writer = csv.DictWriter(csvfile, fieldnames=["Bio_Id","Last_Name","First_Name","late","undertime","total_minutes", "total_ot", "total_nsd", "total_absences"],
extrasaction='ignore', delimiter = ';')
回答by akbsmile
Hi all thank you for answering. I finally found out how to make it. here is the code
大家好谢谢你的回答。我终于知道如何制作了。这是代码
w = csv.writer(file(r'test.csv','wb'), delimiter=';')
w.writerows([["Bio Id","Last Name",.....]])
w.writerows(db.session.execute(selectAttendance))
db.session.commit()
