peewee select（）返回SQL查詢，而不是實際數據

Question

我試圖總結兩列中的值並截斷日期中的日期字段。我已經構造SQL查詢來做到這一點（工作）：

SELECT date_trunc('day', date) AS Day, SUM(fremont_bridge_nb) AS 
Sum_NB, SUM(fremont_bridge_sb) AS Sum_SB FROM bike_count GROUP BY Day 
ORDER BY Day; 

但我再遇到問題時，我嘗試這種格式爲peewee：

Bike_Count.select(fn.date_trunc('day', Bike_Count.date).alias('Day'), 
fn.SUM(Bike_Count.fremont_bridge_nb).alias('Sum_NB'), 
fn.SUM(Bike_Count.fremont_bridge_sb).alias('Sum_SB')) 
.group_by('Day').order_by('Day') 

我沒有得到任何錯誤，但是當我打印出來的變量我存儲在這，它表明：

<class 'models.Bike_Count'> SELECT date_trunc(%s, "t1"."date") AS 
Day, SUM("t1"."fremont_bridge_nb") AS Sum_NB, 
SUM("t1"."fremont_bridge_sb") AS Sum_SB FROM "bike_count" AS t1 ORDER 
BY %s ['day', 'Day'] 

，我已經用Python寫的順利拿到數據的唯一事情是：

Bike_Count.get(Bike_Count.id == 1).date 

Answer 1

如果您只是通過/ order by將一個字符串粘貼到您的組中，Peewee會嘗試將其參數化爲一個值。這是爲了避免SQL注入haxx。

爲了解決這個問題，你可以代替'Day'的group_by()和order_by()電話內使用SQL('Day')。

另一種方法是將函數調用插入GROUP BY和ORDER BY。這裏是你會怎麼做：

day = fn.date_trunc('day', Bike_Count.date) 
nb_sum = fn.SUM(Bike_Count.fremont_bridge_nb) 
sb_sum = fn.SUM(Bike_Count.fremont_bridge_sb) 

query = (Bike_Count 
     .select(day.alias('Day'), nb_sum.alias('Sum_NB'), sb_sum.alias('Sum_SB')) 
     .group_by(day) 
     .order_by(day)) 

或者，如果你喜歡：

query = (Bike_Count 
     .select(day.alias('Day'), nb_sum.alias('Sum_NB'), sb_sum.alias('Sum_SB')) 
     .group_by(SQL('Day')) 
     .order_by(SQL('Day')))