Python 如何从 Flask 应用程序中的 MySQL 查询返回数据？
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How to return data from a MySQL query in a Flask app?
提问by Hugo
I have the following code:
我有以下代码：
import flask as fk
import MySQLdb
import JSONEncoder
class SpecializedJSONEncoder(JSONEncoder):
def default(o):
if isinstance(o, date):
return date.strftime("%Y-%m-%d")
else:
super(SpecializedJSONEncoder, self).default(o)
app = fk.Flask(__name__)
app.json_encoder = SpecializedJSONEncoder
app.debug = True
@app.route("/")
def home():
return "Hello world"
@app.route("/temp")
def temp():
db = MySQLdb.connect("localhost", "root", "","test")
cur = db.cursor()
query = "SELECT DATE(DTM), POM, ROUND(MIN(TMP),1) FROM dados_meteo WHERE POM = %s AND DATE(DTM) >= %s AND DATE(DTM) <= %s"
param = ("Faro", "2013-12-01", "2013-12-05")
cur.execute(query, param)
data = cur.fetchall()
return data.json_encoder()
if __name__ == "__main__":
app.run()
The error returned is: ImportError: No module named JSONEncoder
返回的错误是：ImportError: No module named JSONEncoder
采纳答案by Sean Vieira
Use Flask's built-in jsonifyfunction, as it is already extended to work with dates:
使用 Flask 的内置jsonify函数，因为它已经扩展到可以处理日期：
from Flask import jsonify
@app.route('/temp')
def temp():
# Load database results
# and then ...
return jsonify(data=cur.fetchall())
The data will be returned as an object with a single key (data) containing an array of rows (which will either be represented as arrays or objects depending on what fetchallreturns rows as).
数据将作为一个对象返回，data其中包含一个包含行数组的单个键 ( )（根据fetchall返回行的内容，该对象将表示为数组或对象）。
If you need to serialize more types (as in your case, you are getting back daterather than datetimeinstances, you will need to override Flask's json_encoderproperty with a subclass of JSONEncoderthat knows how to handle your types:
如果您需要序列化更多类型（在您的情况下，您将返回date而不是datetime实例，您将需要json_encoder使用JSONEncoder知道如何处理您的类型的子类覆盖 Flask 的属性：
class SpecializedJSONEncoder(JSONEncoder):
def default(o):
if isinstance(o, date):
return date.strftime("%Y-%m-%d")
else:
super(SpecializedJSONEncoder, self).default(o)
And then you can set it on your Flaskinstance:
然后你可以在你的Flask实例上设置它：
app.json_encoder = SpecializedJSONEncoder
You will now be able to handle dates as well as datetimes.
您现在将能够处理dates 和datetimes。
