我有一个在 celery 中运行的 period_task 查询最新的加密货币价格，但出于某种原因，每次想要显示数据时，我都没有得到更新的记录，我只是得到了新的记录，而由于某种原因，旧的记录被保留了下来。
任务.py
@periodic_task(run_every=(crontab(minute='*/1')), name="Update Crypto rate(s)", ignore_result=True)
def get_exchange_rate():
api_url = "https://api.coinmarketcap.com/v1/ticker/"
try:
exchange_rates = requests.get(api_url).json()
for exchange_rate in exchange_rates:
CryptoPrices.objects.update_or_create(key=exchange_rate['id'],
symbol=exchange_rate['symbol'],
market_cap_usd=round(float(exchange_rate['market_cap_usd']), 3),
volume_usd_24h=round(float(exchange_rate['24h_volume_usd']), 3),
defaults={'value': round(float(exchange_rate['price_usd']), 3)}
)
logger.info("Crypto exchange rate(s) updated successfully.")
except Exception as e:
print(e)
模型.py
class CryptoPrices(models.Model):
key = models.CharField(max_length=255)
value = models.CharField(max_length=255)
symbol = models.CharField(max_length=255)
volume_usd_24h = models.CharField(max_length=255)
market_cap_usd = models.CharField(max_length=255)
View .py
def crypto_ticker(request):
list_prices = CryptoPrices.objects.get_queryset().order_by('pk')
paginator = Paginator(list_prices, 100) # Show 100 prices per page
page = request.GET.get('page')
price = paginator.get_page(page)
return render(request, 'crypto_ticker.html', {'price': price})
模板.html:
{% extends 'base.html' %}
{% load readmore %}
{% block breadcrumbs %}
{{ block.super }} » <a href="{% url 'post_list' %}">Posts </a> »
<a href="{% url 'crypto_ticker' %}">Crypto ticker</a>
{% endblock %}
{% block content %}
<!DOCTYPE html>
<html>
<head>
<title>Crypto ticker</title>
</head>
<body>
<h1 class="center">Crypto ticker</h1>
<hr class="hr-style">
<div class="center">
<h4>{{ prices }} Here you can find all frequently asked questions <br>
if you still have still have any open points, please contact the <a href="#">support</a>.</h4>
</div>
<br>
<div class="paginator">
<span>
{% if price.has_previous %}
<a href="?page=1">« First <a> |</a></a>
<a href="?page={{ price.previous_page_number }}">Previous</a>
{% endif %}
{% if price.has_next %}
<span> Crypto prices - Page {{ price.number }} of {{ price.paginator.num_pages }}.</span>
<a href="?page={{ price.next_page_number }}">Next<a> |</a></a>
<a href="?page={{ price.paginator.num_pages }}">Last »</a>
{% endif %}
</span>
</div>
<table class="table centercontentfloat class-three-box">
<thead>
<tr style="font-size: small">
<th>Ranking</th>
<th>Symbol</th>
<th>Name</th>
<th>Price</th>
<th>Market Cap (USD)</th>
<th>24 hrs. Volume (USD)</th>
</tr>
</thead>
<tbody>
{% for price in price %}
<tr style="font-size: small">
<td>{{ price.id }}</td>
<td>{{ price.symbol }}</td>
<td>{{ price.key }}</td>
<td>{{ price.value }} $</td>
<td style="font-size: small">{{ price.market_cap_usd }} $</td>
<td style="font-size: small">{{ price.volume_usd_24h }} $</td>
</tr>
{% endfor %}
</tbody>
</table>
<div class="paginator">
<span>
{% if price.has_previous %}
<a href="?page=1">« First <a> |</a></a>
<a href="?page={{ price.previous_page_number }}">Previous</a>
{% endif %}
{% if price.has_next %}
<span> Crypto prices - Page {{ price.number }} of {{ price.paginator.num_pages }}.</span>
<a href="?page={{ price.next_page_number }}">Next<a> |</a></a>
<a href="?page={{ price.paginator.num_pages }}">Last »</a>
{% endif %}
</span>
</div>
{% endblock %}
为什么我从 coinmarketcap api 获取的记录被保存/显示两次，有什么明显的原因吗？
如果我浏览页面，我会返回如下内容:
Crypto prices - Page 1 of 21. Next | Last » Ranking Symbol Name Price Market Cap (USD) 24 hrs. Volume (USD) 1 BTC bitcoin 3795.6465 $ 66594617840.0 $ 8296474984.64 $ 2 ETH ethereum 143.9996 $ 15106822040.0 $ 5043716023.22 $
在第二页上:
« First | Previous Crypto prices - Page 2 of 22. Next | Last » Ranking Symbol Name Price Market Cap (USD) 24 hrs. Volume (USD) 101 BTC bitcoin 3798.3016 $ 66641201438.0 $ 8304474934.43 $ 102 ETH ethereum 144.0825 $ 15115524904.0 $ 5048205218.98 $
我不希望 BTC 也在第二页，只有一次在第一页？!？
看起来如果我浏览页面，记录不会得到更新，它们会在每次 period_task 运行后一个接一个地保存
亲切的问候
最佳答案
你误解了 update_or_create作品。这是什么docs说:
The
update_or_createmethod tries to fetch an object from database based on the givenkwargs. If a match is found, it updates the fields passed in thedefaultsdictionary.
所以在
kwargs您只传递获得匹配所需的值，而不是更新。大概路过id或 symbol应该是唯一的 kwargs你需要。你要更新的所有参数都需要传递给defaults .CryptoPrices.objects.update_or_create(
key=exchange_rate['id'],
symbol=exchange_rate['symbol'],
defaults=dict(
market_cap_usd=round(float(exchange_rate['market_cap_usd']), 3),
volume_usd_24h=round(float(exchange_rate['24h_volume_usd']), 3),
value= round(float(exchange_rate['price_usd']), 3))
)
关于python - Django objects.update_or_create，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/54749170/