Django - 如何在模板中获取长度和计数命令？ （模板中的查询集）

Question

我有这些模块：Django 中的销售、性别和类型。

表 1：

class Sales(models.Model):
    sname = models.CharField(max_length=100, default="-")
    sgender = models.ForeignKey(MainGender, on_delete=models.CASCADE)
    stype = models.ForeignKey(MainTypes, on_delete=models.CASCADE)
    sdate = models.TextField(default="-")   

    +------+-----+------+------+
    | name |gende| type | date |
    +------+-----+------+------+
    | A    | 1   | 1    | 2019 |
    +------+-----+------+------+
    | B    | 2   | 1    | 2018 |
    +------+-----+------+------+
    | A    | 1   | 3    | 2019 |
    +------+-----+------+------+
    | C    | 2   | 3    | 2017 |
    +------+-----+------+------+
    | A    | 1   | 2    | 2019 |
    +------+-----+------+------+

表 2（键）

class MainGender(models.Model):
    mid = models.CharField(max_length=25, default="-")
    mgender = models.CharField(max_length=25, default="-")

+----+--------+
| id | gender |
+----+--------+
| 1  | Male   |
+----+--------+
| 2  | Female |
+----+--------+
| 3  | -      |
+----+--------+

表 3（键）

class MainTypes(models.Model):
    tid = models.CharField(max_length=50, default="-")
    ttype = models.CharField(max_length=50, default="-")

+----+------+
| id | type |
+----+------+
| 1  | U1   |
+----+------+
| 2  | X2   |
+----+------+
| 3  | B1   |
+----+------+
| 4  | H3   |
+----+------+

然后，我想统计主表中的所有东西，并在模板中显示如下

+---------------+---+
| Total records | 5 |
+---------------+---+
| Male          | 3 |
+---------------+---+
| Female        | 2 |
+---------------+---+
| Type U1       | 2 |
+---------------+---+
| Type X2       | 1 |
+---------------+---+
| Type B1       | 2 |
+---------------+---+
| Type H3       | 0 |
+---------------+---+

我只能通过下面的代码获取模板中的总记录

在views.py中

def Sale_p(request):
    saless = Sale.objects.all()
    return render(request, 'sale.html', {'sales':saless})

我在模板（sale.html）中尝试了这些代码

{{ sales|length }} (gives you total records in Table 1, in this example 5)

{{ sales.gender|length }} (gives nothing)

{{ sales.type|length }} (gives nothing) 

{{ sales.gender_set|length }} (gives nothing)

{{ sales.type_set|length }} (gives nothing)

{{ sales.gender(1)|length }} (gives nothing)

{{ sales(gender='1')|length }} (gives nothing)

{{ sales.gender.count() }} (gives nothing)

他们没有在模板中工作。我想在记录中查看我们有多少次“男性”或“女性”或类型等等......

在模板中，sale.html

+---------------+--------------------+
| Total records | {{ sales|length }} |
+---------------+--------------------+
| Male          | ?                  |
+---------------+--------------------+
| Female        | ?                  |
+---------------+--------------------+
| Type U1       | ?                  |
+---------------+--------------------+
| Type X2       | ?                  |
+---------------+--------------------+
| Type B1       | ?                  |
+---------------+--------------------+
| Type H3       | ?                  |
+---------------+--------------------+

为他人获取结果的代码应该是什么？ 或者我应该在views.py中使用不同的方式？

Answer 1

请参考以下链接：

https://docs.djangoproject.com/en/3.0/ref/templates/builtins/