Question

// Django 2.2.2 // sqlite3

我正在使用Django Aggregate将各种统计值传递给Django模板。

平均，计数运行良好。但是Variance无法正常工作，并给我OperationError。

import networkx as nx
import numpy as np
import matplotlib.pyplot as plt

G = nx.Graph()
G.add_edges_from(
    [('A', 'B'), ('A', 'C'), ('D', 'B'), ('E', 'C'), ('E', 'F'),
     ('B', 'H'), ('B', 'G'), ('B', 'F'), ('C', 'G')])

val_map = {'A': 1.0,
           'D': 0.5714285714285714,
           'H': 0.0}

values = [val_map.get(node, 0.25) for node in G.nodes()]
%matplotlib inline 
nx.draw_networkx(G, cmap = plt.get_cmap('jet'), node_color = values)

nx.draw(G)
plt.show()

AttributeError                            Traceback (most recent call last)
<ipython-input-13-127734f4f34b> in <module>()
     14 values = [val_map.get(node, 0.25) for node in G.nodes()]
     15 get_ipython().magic('matplotlib inline')
---> 16 nx.draw_networkx(G, cmap = plt.get_cmap('jet'), node_color = values)
     17 
     18 nx.draw(G)

1 frames
/usr/local/lib/python3.6/dist-packages/networkx/drawing/nx_pylab.py in draw_networkx_edges(G, pos, edgelist, width, edge_color, style, alpha, edge_cmap, edge_vmin, edge_vmax, ax, arrows, label, **kwds)
    520         lw = width
    521 
--> 522     if not cb.is_string_like(edge_color) \
    523            and cb.iterable(edge_color) \
    524            and len(edge_color) == len(edge_pos):

AttributeError: module 'matplotlib.cbook' has no attribute 'is_string_like'

当我在模型方法中编写时，方差起作用。但是在views.py中，无法正常工作。我不知道这两者之间有什么区别。

views.py

Traceback (most recent call last):
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/core/handlers/base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/core/handlers/base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/Users/miguel/Outsourcings/myProject/project_app/views.py", line 116, in project_report
    print(subject)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/models/query.py", line 250, in __repr__
    data = list(self[:REPR_OUTPUT_SIZE + 1])
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/models/query.py", line 274, in __iter__
    self._fetch_all()
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/models/query.py", line 1242, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/models/query.py", line 55, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1100, in execute_sql
    cursor.execute(sql, params)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/debug_toolbar/panels/sql/tracking.py", line 186, in execute
    return self._record(self.cursor.execute, sql, params)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/debug_toolbar/panels/sql/tracking.py", line 124, in _record
    return method(sql, params)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/backends/utils.py", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/miguel/Outsourcings/myProject/myvenv/lib/python3.6/site-packages/django/db/backends/sqlite3/base.py", line 383, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: user-defined aggregate's 'finalize' method raised error
[03/Jun/2019 20:41:24] "GET /project/report/7 HTTP/1.1" 500 224730

models.py

def project_report(request, pk):
    project = get_object_or_404(ProjectModel.objects, pk=pk)
    subject = project.subject_for_project.filter(status='on', party_status='join').annotate(feel_avg=Avg('datamodel__feeling'),
                 pain_avg=Avg('datamodel__pain'),
                 side_count=Count(Case(
                     When(datamodel__flag='side', then=1),
                     output_field=IntegerField(),
                 )),
                 # this part is not working
                 pain_variance=Variance('datamodel__pain')
                 )
    print(subject)
    context = {
        'project':project,
        'subject':subject,
    }
    return render(request, 'project/project_report.html, context)

根据django 2.2发行说明，我读到sqlite环境也支持variance，但是如果我不能在视图中使用它，我想找到另一种方法。谢谢。

Answer 1

尽管使用version 2.2 of Django，但在sqlite数据库环境中它似乎仍不完全支持Variance。

使用类中的方法创建错误时不会引发错误。但是，当我在views.py中创建FBV并从父模型加载FBV时，会发生错误。

我将本地数据库更改为仅Postgresql，所以错误消失了。

django 2.2“用户定义的聚合的“ finalize”方法引发错误”

1 个答案: