Django JSONField内部的ArrayField [英] Django JSONField inside ArrayField

问题描述

models.py

  locations = ArrayField（JSONField（null = True，blank = True），blank = True，null = True）
  

插入

  location_arr = [{locations：loc1，amount：Decimal（100.00）}，{locations：loc2，amount：Decimal（200.25）}] 
 instance.locations = location_arr 
 instance.save（）
  

当我这样做，我得到了

列位置的类型为jsonb []，但表达式为text []

LINE 1：... d= 2517，locations= ARRAY ['{loc ...

提示：您需要重写或转换表达式

所以我试图使用以下方式转储：

  import json 
 location_arr = [{locations：loc1，amount：Decimal（100.00）}，{locations ：loc2，amount：Decimal（200.25）}] 
 instance.locations = json.dumps（location_arr）
 instance.save（）
  / pre> 
 
 
然后我得到这个
 
 
 LINE 1：... d = 2517，locations='[{loc：... 
 
 
 
 DETAIL：[必须引入显式指定的数组维度。 
 
我正在使用：
 
 
 Django 1.9 
 
 
 Python 2.7 
 
 
 Postgres 9.4.10 
 
 
 psycopg2 2.6.2 
 
 
 
 
解决方案
首先，让我们仔细看看这个重要的文本，从 Postgresql数组文档。
 
 
提示：数组不是集合;搜索特定的数组元素可以是
数据库设计的标志。考虑使用一个单独的表与
行为每个项目将是一个数组元素。这将更容易
进行搜索，并且可能会对大量的
元素进行更好的扩展。
 
 
 
 
  
 
 
现在我们在这里有什么？一个容纳json字段的数组。这是一个等待发生的灾难。请规范您的资料。
 
I have a problem inserting to a field using ArrayField with JSONField inside.

models.py
locations = ArrayField(JSONField(null = True,blank = True), blank=True, null = True)
Insert
location_arr = [{"locations" : "loc1","amount":Decimal(100.00)},{"locations" : "loc2","amount":Decimal(200.25)}]
instance.locations = location_arr
instance.save()
When I do this, I got

  
column "locations" is of type jsonb[] but expression is of type text[]
  
  
LINE 1: ...d" = 2517, "locations" = ARRAY['{"loc...
  
  
Hint: You will need to rewrite or cast the expression.
So I tried to dump it using:
import json
location_arr = [{"locations" : "loc1","amount":Decimal(100.00)},{"locations" : "loc2","amount":Decimal(200.25)}]
instance.locations = json.dumps(location_arr)
instance.save()
then I got this

  
LINE 1: ...d" = 2517, "locations" = '[{"loc":...
  
  
DETAIL:  "[" must introduce explicitly-specified array dimensions.
I am using:

Django 1.9
Python 2.7
Postgres 9.4.10
psycopg2 2.6.2

解决方案
First of all, let's take a close look at this important text from the Postgresql Arrays document.

  
Tip: Arrays are not sets; searching for specific array elements can be
  a sign of database misdesign. Consider using a separate table with a
  row for each item that would be an array element. This will be easier
  to search, and is likely to scale better for a large number of
  elements.
Most of the time, you should not be using arrays. The same goes for JSONB. If you find yourself searching inside JSONB fields all the time the above statement is equally valid for JSONB.

Now what do we have here? A an array that holds json field. This is a diaster waiting to happen. Please normalize your data.

                        
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