我有一个Django应用，其中包含一组市场，这些市场通过外键连接到价格历史记录，该价格历史记录在models.py中定义如下：
class Market(models.Model):
title = models.CharField(max_length=50, default="")
current_price = models.DecimalField(max_digits=5, decimal_places=2)
description = models.TextField(default="")
shares_yes = models.IntegerField(default=0)
shares_no = models.IntegerField(default=0)
b = models.IntegerField(default=100)
cost_function = models.IntegerField(default=0)
def __str__(self):
return self.title[:50]
def get_absolute_url(self):
return reverse('market_detail', args=[str(self.id)])
class Price(models.Model):
market = models.ForeignKey(
Market,
on_delete=models.CASCADE,
related_name='prices',
default=None)
price = models.DecimalField(
max_digits=5,
decimal_places=2,
default=None)
def __str__(self):
return str(self.price)
def get_absolute_url(self):
return reverse('market_list')
在模板中，用户可以查看当前市场价格，并可以买卖与该市场有关的股票。他们还应该看到一个价格图，我正尝试通过将其从market.prices序列化为price_items的方式来填充价格图（从views.py开始，忽略labels中的玩具值） ：
class ChartData(APIView):
authentication_classes = []
permission_classes = []
def get(self, request, pk):
market = Market.objects.get(pk=pk)
price_items = serializers.serialize('json', market.prices.get_queryset(), fields=('price'))
labels = [1, 2, 3, 4] # Toy labels
data = {
"labels": labels,
"prices": price_items}
return Response(data)
urls.py的相关部分如下：
urlpatterns = [
path('', HomePageView.as_view(), name='home'),
path('list/', MarketListView.as_view(), name='market_list'),
path('<int:pk>/', MarketDetailView.as_view(), name='market_detail'),
path('<int:pk>/buy/', views.buy, name='buy'),
path('<int:pk>/sell/', views.sell, name='sell'),
# url(r'^api/chart/data/$', ChartData.as_view()),
path('<int:pk>/api/chart/data/', ChartData.as_view(), name='chart_data'),
]
我的问题是：我无法弄清楚如何简单地获得输出端价格的干净清单，以将其输入到位于data.prices的折线图中：
<script>
{% block jquery %}
var endpoint = "{% url 'chart_data' market.id %}"
var defaultData = []
var labels = []
$.ajax({
method: "GET",
url: endpoint,
success: function(data){
labels = data.labels
defaultData = data.prices
var ctx = document.getElementById('myChart').getContext('2d');
var myChart = new Chart(ctx, {
type: 'line',
data: {
labels: labels,
datasets : [{
label: 'Market price',
data: defaultData
}]
},
options: {
scales: {
yAxes: [{
ticks: {
suggestedMin: 0,
suggestedMax: 1
}
}]
}
}
})
}
})
{% endblock %}
</script>
这是我在相关<int:pk>/api/chart/data/网址中的json中获取的内容：
{"labels":[1,2,3,4],"prices":"[{\"model\": \"markets.price\", \"pk\": 4, \"fields\": {\"price\": \"0.90\"}}, {\"model\": \"markets.price\", \"pk\": 5, \"fields\": {\"price\": \"0.91\"}}, {\"model\": \"markets.price\", \"pk\": 6, \"fields\": {\"price\": \"0.92\"}}, {\"model\": \"markets.price\", \"pk\": 7, \"fields\": {\"price\": \"0.92\"}}, {\"model\": \"markets.price\", \"pk\": 8, \"fields\": {\"price\": \"0.93\"}}, {\"model\": \"markets.price\", \"pk\": 12, \"fields\": {\"price\": \"0.92\"}}, {\"model\": \"markets.price\", \"pk\": 13, \"fields\": {\"price\": \"0.93\"}}, {\"model\": \"markets.price\", \"pk\": 14, \"fields\": {\"price\": \"0.88\"}}, {\"model\": \"markets.price\", \"pk\": 15, \"fields\": {\"price\": \"0.87\"}}, {\"model\": \"markets.price\", \"pk\": 16, \"fields\": {\"price\": \"0.86\"}}, {\"model\": \"markets.price\", \"pk\": 17, \"fields\": {\"price\": \"0.85\"}}, {\"model\": \"markets.price\", \"pk\": 18, \"fields\": {\"price\": \"0.86\"}}, {\"model\": \"markets.price\", \"pk\": 19, \"fields\": {\"price\": \"0.87\"}}, {\"model\": \"markets.price\", \"pk\": 20, \"fields\": {\"price\": \"0.86\"}}, {\"model\": \"markets.price\", \"pk\": 26, \"fields\": {\"price\": \"0.87\"}}, {\"model\": \"markets.price\", \"pk\": 27, \"fields\": {\"price\": \"0.88\"}}, {\"model\": \"markets.price\", \"pk\": 28, \"fields\": {\"price\": \"0.87\"}}, {\"model\": \"markets.price\", \"pk\": 29, \"fields\": {\"price\": \"0.86\"}}, {\"model\": \"markets.price\", \"pk\": 30, \"fields\": {\"price\": \"0.85\"}}, {\"model\": \"markets.price\", \"pk\": 31, \"fields\": {\"price\": \"0.83\"}}, {\"model\": \"markets.price\", \"pk\": 32, \"fields\": {\"price\": \"0.85\"}}, {\"model\": \"markets.price\", \"pk\": 33, \"fields\": {\"price\": \"0.86\"}}, {\"model\": \"markets.price\", \"pk\": 34, \"fields\": {\"price\": \"0.85\"}}, {\"model\": \"markets.price\", \"pk\": 35, \"fields\": {\"price\": \"0.86\"}}, {\"model\": \"markets.price\", \"pk\": 36, \"fields\": {\"price\": \"0.87\"}}, {\"model\": \"markets.price\", \"pk\": 37, \"fields\": {\"price\": \"0.88\"}}, {\"model\": \"markets.price\", \"pk\": 38, \"fields\": {\"price\": \"0.89\"}}]"}
我在做什么错了？
答案 0 :(得分：0)
之所以得到结果，是因为您两次对price_items进行了序列化。如果使用的是django序列化程序，则应仅使用HttpResponse并返回数据。
price_items = serializers.serialize('json', market.prices.get_queryset(), fields=('price'))
return HttpResponse(price_items,content_type='application/json')
如果您也想在响应中返回标签，那么我认为这应该可行：
price_items = market.prices.get_queryset().values() #include the fields you want to display in .values() as strings eg .values('prices')
labels = [1,2,3,4]
data = {
"labels": labels,
"prices": price_items}
return JsonResponse(data)
您可能需要根据Django模型修改price_items查询
答案 1 :(得分：0)
您可以/应该使用序列化器：
from rest_framework import serializers
class MySerializer(serializers.Serializer):
labels = serializers.ListField(default=[1, 2, 3, 4])
prices = serializers.SerializerMethodField()
def get_prices(self, obj):
return obj.prices.values_list('price', flat=True)
class ChartData(RetrieveAPIView):
queryset = Market.objects.all()
authentication_classes = []
permission_classes = []
serializer_class = MySerializer