django.db.utils.IntegrityError：唯一約束失敗：beachprofile_beach.beach_id

Question

我正在為海灘配置文件設置評論功能，並想在beach.html中提交評論表並重定向回原始的海灘配置文件。

我在海灘配置文件中包含一個addreview按鈕和評論列表，但問題是，當我打開海灘配置文件時，我選擇它告訴我，beachprofile_beach.beach_id的唯一約束失敗。 所以我認為這是因為在用戶查看之后，再次返回到beachProfile視圖，並將相同的海灘信息再次存儲到表中。 但是我真的不知道如何解決它。

這是beachProfile視圖中的一部分，當我打開新的海灘配置文件頁面時，可以將海灘信息存儲到表Beach中。

def beachProfile(request):    
    thisname = request.build_absolute_uri()
    name = thisname.split('=')[-1].replace("%20"," ")
    name2 = thisname.split('=')[-1].replace("%20","+")
    oldname = name
    #print(name  + 'hi testing')
    if oldname == '1' or oldname == '2':
        name = thisname.split('=')[2].replace("%20"," ")
        name = name.split('?')[0]
        print(name)
        name2 = thisname.split('=')[2].replace("%20","+")
        name2 = name2.split('?')[0]

    testsafe = thisname.split('=')[1]
    testsafe = int(testsafe[0])
    if testsafe == 0:
        safe=True
        halfsafe=False
    elif testsafe == 2:
        safe=False
        halfsafe=False
    else:
        safe=False
        halfsafe=True
    thisBeach = requests.get("https://maps.googleapis.com/maps/api/geocode/json?address="+name2+"&key=AIzaSyAH43dAThEg8WJge9cuFa3vbnBhLRSlJDQ")
    beachjson = thisBeach.json()
    latitude = beachjson["results"][0]["geometry"]["location"]["lat"]
    longitude = beachjson["results"][0]["geometry"]["location"]["lng"]


    response = requests.get("https://api.darksky.net/forecast/fef06c56fa2906ef3255d9b99bfb02de/"+str(latitude)+","+str(longitude))
    forecast = response.json()
    windspeedcurr = forecast["currently"]["windSpeed"]
    tempcurr = forecast["currently"]["temperature"]
    uvcurr = forecast["currently"]["uvIndex"]
    summary = []
    for i in range(len(forecast["daily"]["data"])):
        summary.append("/DarkSky-icons/PNG/"+forecast["daily"]["data"][i]["icon"]+".png")

    thumbnail = "https://maps.googleapis.com/maps/api/staticmap?center="+str(latitude)+","+str(longitude)+"&zoom=14&size=400x400&key=AIzaSyAH43dAThEg8WJge9cuFa3vbnBhLRSlJDQ"
     beach = Beach.objects.filter(
        beachname=name,
        safety=testsafe,
        lat=latitude,
        lng=longitude,
        ).first()

    if beach is None:
        beach = Beach.objects.create(
            beachname=name,
            safety=testsafe,
            lat=latitude,
            lng=longitude,
        )
    is_favourite=False
    if oldname =='1':
        """
        if beach.fav.filter(id=request.user.id).exists():
            pass
        else:
        """
        print('adding user')
        beach.fav.add(request.user)
        is_favourite=True
    if oldname =='2':
        if beach.fav.filter(id=request.user.id).exists():
            beach.fav.remove(request.user)
        else:
            pass

    return render(request, 'users/beach.html', {'latitude': latitude, 'longitude': longitude, 'summary': summary, 'thumbnail': thumbnail, 'wind': windspeedcurr, 'temp': tempcurr, 'uvindex': uvcurr, 'name': name, 'rating': 5, 'safe': safe, 'halfsafe': halfsafe, 'is_fav':is_favourite, 'safety':testsafe})

對於我的評論模型和評論模型（部分）：

class Beach(models.Model):
    beach_id = models.AutoField(primary_key = True)
    beachname = models.CharField(max_length=50, unique = True)
    safety = models.IntegerField(default=0) #default is safe? 
    lat = models.IntegerField()
    lng = models.IntegerField()
    fav = models.ManyToManyField(User, related_name="fav",blank=True)
    class Meta:
        unique_together = ["beachname", "safety", "lat", "lng"]
    def __str__(self):
        return self.beachname

    def average_rating(self):
        all_ratings = map(lambda x: x.rating, self.review_set.all())
        return np.mean(all_ratings)

class Review(models.Model):
    review_id = models.AutoField(primary_key = True)
    beach = models.ForeignKey(Beach, on_delete = models.CASCADE)
    pub_date = models.DateTimeField('date published')
    user_reviewed = models.ManyToManyField(User, related_name="reviewer",blank=True)
......

與沙灘相關的urls.py像這樣：

    url(r'^beachProfile/', beach_views.beachProfile, name='beachProfile'),
    url(r'(?P<beach_id>\d+)/fav/$', beach_views.fav, name="fav"),

    url(r'^$', beach_views.review_list, name='review_list'),
    url(r'(?P<beach_id>\d+)/(?P<review_id>[0-9]+)/$', beach_views.review_detail, name='review_detail'),
    url(r'(?P<beach_id>\d+)/add_review/$', beach_views.add_review, name='add_review'),#add review to the user with same id
    url(r'^user/(?P<username>\w+)/$', beach_views.user_review_list, name='user_review_list'),

下面的代碼是我添加評論的代碼。 我真的不知道如何在審閱之前直接回到我的個人資料頁面，所以我只是直接放置個人資料頁面鏈接，但不包括喜歡的號碼（收藏夾= 1或2），因為我不知道如何從beachProfile。 我真的很想知道如何返回原始的個人資料頁面。 危險是一個經過計算的數字，在海灘模型中稱為安全性，海灘名稱是海灘的名稱。

@login_required
def add_review(request, beach_id):
    beach = get_object_or_404(Beach, beach_id=beach_id)
    form = ReviewForm(request.POST)
    if form.is_valid():
        rating = form.cleaned_data['rating']
        comment = form.cleaned_data['comment']
        user_name = request.user.username
        review = Review()
        review.beach = beach
        review.user_name = user_name
        review.rating = rating
        review.comment = comment
        review.pub_date = datetime.datetime.now()
        review.save()
        # Always return an HttpResponseRedirect after successfully dealing
        # with POST data. This prevents data from being posted twice if a
        # user hits the Back button.
        #?danger={{safety}}?name={{name}}?fav=1
        #"beachProfile?danger='+danger+'?name='+marker.title+'" is this correct way???
        return HttpResponseRedirect("beachProfile?danger='+beach.safety+'?name='+beach.beachname+'")

    return render(request, 'users/beach.html', {'beach': beach, 'form': form})

在beach.html中，“添加您的評論”是一個進入表單以提交用戶評論的按鈕

<div id="reviews">
      <h2>Add your Review</h2>
      <form action="{% url 'add_review' beach.beach_id %}" method="post" class="form">
        {% csrf_token %}
        {% bootstrap_form form %}
        {% bootstrap_form form layout='inline' %}
        {% buttons %}
        <button type="submit" class="btn btn-primary">
        {% bootstrap_icon "star" %} Add
        </button>
        {% endbuttons %}
      </form>
    </div>

我不確定我在哪里錯了，因為我仍然不了解這些知識。 請任何人都可以幫助解決這些錯誤。

我想知道發生IntegrityError的問題是因為也許我兩次保存了任何海灘實例，但是我檢查了所有代碼，所以唯一保存實例的地方是在beachProfile視圖中，上面可以看到代碼。 但是我不知道為什么這是錯誤的。 錯誤消息是：

Apply all migrations: admin, auth, beachprofile, contenttypes, sessions
Running migrations:
  Applying beachprofile.0007_auto_20190411_0432...Traceback (most recent call last):
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\sqlite3\base.py", line 298, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: UNIQUE constraint failed: beachprofile_beach.beach_id

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\management\__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\management\__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\management\base.py", line 316, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\management\base.py", line 353, in execute
    output = self.handle(*args, **options)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\management\base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\management\commands\migrate.py", line 203, in handle
    fake_initial=fake_initial,
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\migrations\executor.py", line 117, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\migrations\executor.py", line 147, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\migrations\executor.py", line 244, in apply_migration
    state = migration.apply(state, schema_editor)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\migrations\migration.py", line 124, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\migrations\operations\fields.py", line 84, in database_forwards
    field,
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\sqlite3\schema.py", line 309, in add_field
    self._remake_table(model, create_field=field)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\sqlite3\schema.py", line 274, in _remake_table
    self.quote_name(model._meta.db_table),
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\base\schema.py", line 133, in execute
    cursor.execute(sql, params)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\utils.py", line 100, in execute
    return super().execute(sql, params)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\backends\sqlite3\base.py", line 298, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: UNIQUE constraint failed: beachprofile_beach.beach_id

我更改后的錯誤未更改，請獲取“海灘否則創建它”

beach = Beach.objects.filter(
        beachname=name,
        safety=testsafe,
        lat=latitude,
        lng=longitude,
        ).first()

    if beach is None:
        beach = Beach.objects.create(
            beachname=name,
            safety=testsafe,
            lat=latitude,
            lng=longitude,
        )

所以我認為問題可能不在這里。 我把我的urls.py放在上面。 我還有其他htmls：review_details.html用於在評論列表中獲取評論的詳細信息，review_list.html用於獲取最新評論的列表，以及user_review_list.html（這只是添加帶有評論用戶名的頭以擴展review_list）以獲得評論列表中評論的詳細信息（您可以通過在海灘的評論列表中單擊用戶名來獲取評論）

同樣在review_detail.html中：

<!--go back to the profile page bug here = no idea of fav number ??????-->>
<h2><a href="{% url '?danger={{review.beach.safety}}?name={{review.beach.beachname}}?fav=1' %}">{{ review.beach.beachname }}</a></h2>

當我單擊海灘名稱時，我想轉到個人資料頁面。 但是重定向URL可能不是那么正確，而add_reviews函數也遇到了同樣的問題。

Answer 1

歡迎來到StackOverflow！

看起來，當您指定模型時，主鍵具有默認值。 主鍵必須是唯一的。 因此，在您的default=1約束下，如果未指定鍵，則將其設置為1 。 AutoField在於它將處理主鍵的設置。

https://docs.djangoproject.com/zh-CN/2.2/ref/models/fields/#autofield

一個IntegerField，它根據可用的ID自動遞增。 您通常不需要直接使用它； 如果沒有另外指定，主鍵字段將自動添加到模型中。

因此，我建議從模型的主鍵定義中刪除default=1

class Beach(models.Model):
    beach_id = models.AutoField(primary_key=True)
    ...,

與評論相同：

class Review(models.Model):
    review_id = models.AutoField(primary_key=True)
    ...,

---

因此，如果我了解您要執行的操作，則會發現此代碼塊存在一些問題。

beach = Beach(Beach.objects.get(), beachname=name, safety=testsafe, lat=latitude, lng=longitude)
    if beach.beach_id == None and beach.beachname == None:
        beach.save()
    else:
        pass

當您調用beach = Beach(Beach.objects.get(), beachname=name, safety=testsafe, lat=latitude, lng=longitude)您正在內存中創建新的Beach模型，並且beach_id尚未設置beach_id因此不會對其進行設置尚未保存到您的數據庫。

您好像要檢查Beach已經存在。

您可以使用以下方法做到這一點：

# check if beach exists
# first will return none if no records are returned
beach = Beach.objects.filter(
    beachname=name,
    safety=testsafe,
    lat=latitude,
    lng=longitude,
).first()

if beach is None:
    beach = Beach.objects.create(
        beachname=name,
        safety=testsafe,
        lat=latitude,
        lng=longitude,
    )

如果我不明白您要在這里做什么，請隨時進行詳細說明。