Python 如何在Django中求一个字段的和

如何呈现特定字段值的总计？正如您所看到的，我在这里使用的是反向关系，因为我有一个外键（我不确定这是否有区别）。例如，如果我想要

'ab'

字段中的值的总和，我会怎么做。我知道我必须使用聚合或注释方法。在我的特殊情况下会是什么样子

型号.py

class Batting(models.Model):
    id = models.IntegerField(db_column='ID', primary_key=True)
    playerid = models.ForeignKey('PlayerLkup', models.DO_NOTHING, db_column='playerID', blank=True, null=True)
    g = models.IntegerField(db_column='G', blank=True, null=True
    ab = models.IntegerField(db_column='AB', blank=True, null=True)
    year = models.IntegerField(db_column='Year', blank=True, null=True) 
    complete_name = models.CharField(max_length=50, blank=True, null=True)

class PlayerLkup(models.Model):
    playerid = models.CharField(db_column='playerID', primary_key=True, max_length=255)
    birthday = models.IntegerField(db_column='birthDay', blank=True, null=True)
    namefirst = models.CharField(db_column='nameFirst', max_length=255, blank=True, null=True)
    namelast = models.CharField(db_column='nameLast', max_length=255, blank=True, null=True)

from django.shortcuts import render
from .models import PlayerLkup


def player_info(request, playerid):
    playerdata = PlayerLkup.objects.get(playerid=playerid)
    battingstats = playerdata.batting_set.all()
    return render(request, 'careerstats/playerpage.html', {'playerdata': playerdata, 'battingstats': battingstats})

视图.py

class Batting(models.Model):
    id = models.IntegerField(db_column='ID', primary_key=True)
    playerid = models.ForeignKey('PlayerLkup', models.DO_NOTHING, db_column='playerID', blank=True, null=True)
    g = models.IntegerField(db_column='G', blank=True, null=True
    ab = models.IntegerField(db_column='AB', blank=True, null=True)
    year = models.IntegerField(db_column='Year', blank=True, null=True) 
    complete_name = models.CharField(max_length=50, blank=True, null=True)

class PlayerLkup(models.Model):
    playerid = models.CharField(db_column='playerID', primary_key=True, max_length=255)
    birthday = models.IntegerField(db_column='birthDay', blank=True, null=True)
    namefirst = models.CharField(db_column='nameFirst', max_length=255, blank=True, null=True)
    namelast = models.CharField(db_column='nameLast', max_length=255, blank=True, null=True)

from django.shortcuts import render
from .models import PlayerLkup


def player_info(request, playerid):
    playerdata = PlayerLkup.objects.get(playerid=playerid)
    battingstats = playerdata.batting_set.all()
    return render(request, 'careerstats/playerpage.html', {'playerdata': playerdata, 'battingstats': battingstats})

---

您可以尝试以下方式进行聚合

from django.db.models import Sum
result = Batting.objects.aggregate(sum_of_ab=Sum("ab"))
print result["sum_of_ab"]

要获取与特定播放机关联的所有

ab

字段的总和，可以先修改查询以进行筛选

from django.db.models import Sum

playerdata = PlayerLkup.objects.get(playerid=playerid)
result = Batting.objects.filter(playerid=playerdata).aggregate(sum_of_ab=Sum("ab"))
print result["sum_of_ab"]

---

这就是你的意思吗？击球模型中每个物体的所有AB整数之和

from django.shortcuts import render
from .models import PlayerLkup, Batting


def player_info(request, playerid):
    count = 0
    foo = Batting.objects.filter(playerid=playerid)
    for x in foo:
        count += int(x.ab)
    return render(request, 'careerstats/playerpage.html', {'playerdata': playerdata, 'battingstats': battingstats, 'count':count})

---

文档中有一个注释示例可能适合这里-

total_ab = PlayerLkup.objects.get(playerid=playerid).annonate(total_ab=Sum('batting__ab'))

（警告！）我还没有测试过这个

查看示例以了解更多信息

player = PlayerLkup.objects.get(playerid='FILL IN ID OF PLAYER HERE')
player_abs = Batting.objects.filter(playerid=player).values('ab')

我很确定，只要检索一个值，就不需要执行SUM或COUNT之类的任何操作

此外，您可能会混淆外键和多对多

您的观点可以是：

def player_info(request, playerid):
    player = PlayerLkup.objects.get(playerid=playerid)
    player_stats = Batting.objects.get(playerid=player)
    player_abs = player_stats.ab
    # below line should be same value as above
    player_abs = Batting.objects.filter(playerid=player).values('ab')
    context = {
        'player': player,
        'player_stats': player_stats,
        'player_abs': player_abs
    }
    return render(request,'careerstats/playerpage.html', context)