Question

我正在尝试使用Django prefetch_related，因为下面显示的模型LanguageCode和Flag之间存在1对多关系（我试图显示flagIconPath），但我似乎无法使views.py代码正确，我真的需要一些帮助！

以下是我的views.py表单：

from django.shortcuts import render

from app_data.models import RIAchievement

def ri_achievements(request):

  qs = RIAchievement.objects.all().prefetch_related("??????", "????????")

  return render(request, 'index.html',{'qs': qs})

我应该用什么代码替换???的？

以下是我试图让django prefetch_related显示的字段：

(flag) flagiconpath,
(riachievement) riAchievementTypeUserDescription,
(typeachievement) typeAchievementDescriptionIntl,
(languagecode) languageNameNative,
(flag) flagIconPath,
(languagedetail) languageDetailDescription,
(languagedirection) languageDirectionDescription,
(riusersettings) riUserSettingsDisplayMultipleLanguage,
(typeresumestyle) typeResumeStyleNumber,
(auth_user) id.

以下是我的相关模型：

class RIAchievement(models.Model):
  riAchievementID = models.AutoField(primary_key=True, db_column="riAchievementID")
  userLanguageVersionID = models.ForeignKey(UserLanguageVersion, db_column="userLanguageVersionID", related_name="riAchievement_userLanguageVersionID")
  typeAchievementID = models.ForeignKey(TypeAchievement, db_column="typeAchievementID", related_name="riAchievement_typeAchievementID")
  riAchievementTypeUserDescription = models.CharField(max_length=255, blank=True, null=True, db_column="riAchievementTypeUserDescription")
  riAchievementDescription = models.TextField(max_length=2000, db_column="riAchievementDescription")
  auth_user_id = models.ForeignKey(auth_user, db_column="auth_user_id", related_name="riAchievement_auth_user_id")
  class Meta:
    db_table="riAchievement"

class TypeAchievement(models.Model):
  typeAchievementID = models.AutoField(primary_key=True, db_column="typeAchievementID")
  languageCodeID = models.ForeignKey(LanguageCode, db_column="languageCodeID", related_name="typeAchievement_languageCodeID")
  typeAchievementDescriptionIntl = models.CharField(max_length=255, db_column="typeAchievementDescriptionIntl")
  typeAchievementDescriptionEng = models.CharField(max_length=255, db_column="typeAchievementDescriptionEng")
  typeAchievementAltID = models.IntegerField(db_column="typeAchievementAltID")
  class Meta:
    db_table="typeAchievement"

class UserLanguageVersion(models.Model):
  userLanguageVersionID = models.AutoField(primary_key=True, db_column="userLanguageVersionID")
  auth_user_id = models.ForeignKey(auth_user, db_column="auth_user_id", related_name="userLanguageVersion_auth_user_id")
  languageCodeID = models.ForeignKey(LanguageCode, db_column="languageCodeID", related_name="userLanguageVersion_languageCodeID")
  class Meta:
    db_table="userLanguageVersion"

class LanguageCode(models.Model):
  languagecodeID = models.AutoField(primary_key=True, db_column="languageCodeID")
  languageCodeDescription = models.CharField(max_length=10, db_column="languageCodeDescription")
  baseLanguageCode = models.CharField(max_length=10, db_column="baseLanguageCode")
  languageNameEng = models.CharField(max_length=255, db_column="languageNameEng")
  altLanguageNameEng = models.CharField(max_length=255, blank=True, null=True, db_column="altLanguageNameEng")
  languageNameNative = models.CharField(max_length=255, db_column="languageNameNative")
  altLanguageNameNative = models.CharField(max_length=255, blank=True, null=True, db_column="altLanguageNameNative")
  iso639_1 = models.CharField(max_length=10, blank=True, null=True, db_column="iso639_1")
  iso639_2T = models.CharField(max_length=10, db_column="iso639_2T")
  iso639_2B = models.CharField(max_length=10, db_column="iso639_2B")
  iso639_X = models.CharField(max_length=10, db_column="iso639_X")
  languageDirectionID = models.ForeignKey(LanguageDirection, default=1, db_column="languageDirectionID", related_name="languageCode_languageDirectionID")
  class Meta:
    db_table="languageCode"

class Flag(models.Model):
  flagID = models.AutoField(primary_key=True, db_column="flagID")
  languageCodeID = models.ForeignKey(LanguageCode, db_column="languageCodeID", related_name="flag_languageCodeID")
  flagIconPath = models.CharField(max_length=255, db_column="flagIconPath")
  flagDescription = models.CharField(max_length=255, db_column="flagDescription")
  flagInformation = models.CharField(max_length=255, db_column="flagInformation")
  class Meta:
    db_table="flag"

class auth_user(models.Model):
  auth_user_id = models.AutoField(primary_key=True, db_column="id")
  username = models.CharField(max_length=30, unique=True, db_column="username")
  first_name = models.CharField(max_length=30, db_column="first_name")
  last_name = models.CharField(max_length=30, db_column="last_name")
  email = models.CharField(max_length=75, db_column="email")
  password = models.CharField(max_length=128, db_column="password")
  is_staff = models.BooleanField(db_column="is_staff")
  is_active = models.BooleanField(db_column="is_active")
  is_supervisor = models.BooleanField(db_column="is_supervisor")
  last_login = models.DateTimeField(db_column="last_login")
  date_joined = models.DateTimeField(db_column="date_joined")
  class Meta:
    db_table="auth_user"

class RIUserSettings(models.Model):
  riUserSettingsID = models.AutoField(primary_key=True, unique=True, db_column="riUserSettingsID")
  riUserSettingsPrimaryLanguageCodeID = models.ForeignKey(LanguageCode, db_column="riUserSettingsPrimaryLanguageCodeID", related_name="riUserSettings_riUserSettingsPrimaryLanguageCodeID")
  riUserSettingsDisplayPrimaryLanguage = models.BooleanField(default=False, db_column="riUserSettingsDisplayPrimaryLanguage")
  riUserSettingsDisplayMutipleLanguage = models.BooleanField(default=False, db_column="riUserSettingsDisplayMutipleLanguage")
  riUserSettingsDisplaySingleLanguage = models.BooleanField(default=False, db_column="riUserSettingsDisplaySingleLanguage")
  riUserSettingsPrimaryVirtualKeyboardLanguageVersionID = models.ForeignKey(UserLanguageVersion, db_column="riUserSettingsPrimaryVirtualKeyboardLanguageVersionID", related_name="riUserSettings_riUserSettingsPrimaryVirtualKeyboardLanguageVersionID")
  riUserSettingsDisplayPrimaryVirtualKeyboard = models.BooleanField(default=False, db_column="riUserSettingsDisplayPrimaryVirtualKeyboard")
  riUserSettingsDisplayRIFormattingPreview = models.BooleanField(default=True, db_column="riUserSettingsDisplayRIFormattingPreview")
  typeResumeStyleID = models.ForeignKey(TypeResumeStyle, db_column="typeResumeStyleID", related_name="riUserSettings_typeResumeStyleID")
  auth_user_id = models.ForeignKey(auth_user, db_column="auth_user_id", related_name="riUserSettings_auth_user_id")
  class Meta:
    db_table="riUserSettings"

class LanguageDetail(models.Model):
  languageDetailID = models.AutoField(primary_key=True, unique=True, db_column="languageDetailID")
  languageCodeID = models.ForeignKey(LanguageCode, db_column="languageCodeID", related_name="languageDetail_languageCodeID")
  nativeLanguageCodeID = models.ForeignKey(LanguageCode, db_column="nativeLanguageCodeID", related_name="languageDetail_nativeLanguageCodeID")
  languageDetailDescriptionIntl = models.CharField(max_length=255, db_column="languageDetailDescriptionIntl")
  languageDetailDescriptionEng = models.CharField(max_length=255, db_column="languageDetailDescriptionEng")
  languageDetailDescriptionNative = models.CharField(max_length=255, db_column="languageDetailDescriptionNative")
  displayCapitaliseCountryName = models.BooleanField(default=False, db_column="displayCapitaliseCountryName")
  languageDirectionID = models.ForeignKey(LanguageDirection, default=1, db_column="languageDirectionID", related_name="languageDetail_languageDirectionID")
  flagID = models.ForeignKey(Flag, db_column="flagID", related_name="languageDetail_FlagID")
  languageDetailAltID = models.IntegerField(db_column="languageDetailAltID")
  class Meta:
    db_table="languageDetail"

class LanguageDirection(models.Model):
  languageDirectionID = models.AutoField(primary_key=True, db_column="languageDirectionID")
  languageDirectionDescription = models.CharField(max_length=20, db_column="languageDirectionDescription")
  languageDirDescription = models.CharField(max_length=20, db_column="languageDirDescription")
  textAlign = models.CharField(max_length=20, db_column="textAlign")
  oppositeLanguageDirectionDescription = models.CharField(max_length=20, db_column="oppositeLanguageDirectionDescription")
  oppositeLanguageDirDescription = models.CharField(max_length=20, db_column="oppositeLanguageDirDescription")
  oppositeTextAlign = models.CharField(max_length=20, db_column="oppositeTextAlign")
  class Meta:
    db_table="languageDirection"

class TypeResumeStyle(models.Model):
  typeResumeStyleID = models.AutoField(primary_key=True, db_column="typeResumeStyleID")
  languageCodeID = models.ForeignKey(LanguageCode, db_column="languageCodeID", related_name="typeResumeStyle_languageCodeID")
  typeResumeStyleNumber = models.IntegerField(db_column="typeResumeStyleNumber")
  typeResumeStyleNameIntl = models.CharField(max_length=255, db_column="typeResumeStyleNameIntl")
  typeResumeStyleNameEng = models.CharField(max_length=255, db_column="typeResumeStyleNameEng")
  typeResumeStyleDescriptionIntl = models.CharField(max_length=255, db_column="typeResumeStyleDescriptionIntl")
  typeResumeStyleDescriptionEng = models.CharField(max_length=255, db_column="typeResumeStyleDescriptionEng")
  class Meta:
    db_table="typeResumeStyle"

Answer 1

啊，我的眼睛。请给你的字段适当的Pythonic名字。特别是因为您已经在使用db_column属性，所以您可以保持您的数据库不变，并提供我们实际可以阅读的字段名称。

特别是，您的ForeignKey字段不应该被称为fooId：底层数据库字段是一个ID，但字段不是，它是对实际FK模型的引用。

要回答你的问题，你提到的所有FK都是前向引用，而不是向后引用。因此，您需要在此使用select_related，而不是prefetch_related。

如何让Django prefetch_related工作？

1 个答案: