如何确定我对 API 的 Python 请求调用是否不返回任何数据
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How to determine if my Python Requests call to API returns no data
提问by JohnnyP
I have a query to an job board API using Python Requests. It then writes to a table, that is included in a web page. Sometimes the request will return no data(if there are no open jobs). If so, I want to write a string to the included file instead of the table. What is the best way to identify a response of no data? Is it as simple as: if response = "", or something along those lines? Here is my Python code making the API request:
我使用 Python 请求查询工作板 API。然后写入包含在网页中的表格。有时请求不会返回任何数据（如果没有空缺职位）。如果是这样，我想将字符串写入包含的文件而不是表。识别无数据响应的最佳方法是什么？是否像这样简单：if response = ""，或者类似的东西？这是我发出 API 请求的 Python 代码：
#!/usr/bin/python
import requests
import json
from datetime import datetime
import dateutil.parser
url = "https://data.usajobs.gov/api/Search"
querystring = {"Organization":"LF00","WhoMayApply":"All"}
headers = {
'authorization-key': "ZQbNd1iLrQ+rPN3Rj2Q9gDy2Qpi/3haXSXGuHbP1SRk=",
'user-agent': "[email protected]",
'host': "data.usajobs.gov",
'cache-control': "no-cache",
}
response = requests.request("GET", url, headers=headers, params=querystring)
responses=response.json()
with open('/Users/jcarroll/work/infoweb_branch4/rep_infoweb/trunk/fec_jobs.html', 'w') as jobtable:
jobtable.write("Content-Type: text/html\n\n")
table_head="""<table class="job_table" style="border:#000">
<tbody>
<tr>
<th>Vacancy</th>
<th>Grade</th>
<th>Open Period</th>
<th>Who May Apply</th>
</tr>"""
jobtable.write(table_head)
for i in responses['SearchResult']['SearchResultItems']:
start_date = dateutil.parser.parse(i['MatchedObjectDescriptor']['PositionStartDate'])
end_date = dateutil.parser.parse(i['MatchedObjectDescriptor']['PositionEndDate'])
jobtable.write("<tr><td><strong><a href='" + i['MatchedObjectDescriptor']['PositionURI'] + "'>" + i['MatchedObjectDescriptor']['PositionID'] + ", " + i['MatchedObjectDescriptor']['PositionTitle'] + "</a></strong></td><td>" + i['MatchedObjectDescriptor']['JobGrade'][0]['Code'] + "-" + i['MatchedObjectDescriptor']['UserArea']['Details']['LowGrade']+ " - " + i['MatchedObjectDescriptor']['UserArea']['Details']['HighGrade'] + "</td><td>" + start_date.strftime('%b %d, %Y')+ " - " + end_date.strftime('%b %d, %Y')+ "</td><td>" + i['MatchedObjectDescriptor']['UserArea']['Details']['WhoMayApply']['Name'] + "</td></tr>")
jobtable.write("</tbody></table>")
jobtable.close
回答by schwobaseggl
You have a couple of options depending on what the response actually is. I assume, case 3 applies best:
您有几个选项，具体取决于响应的实际内容。我认为，情况 3 最适用：
# 1. Test if response body contains sth.
if response.text:
# ...
# 2. Handle error if deserialization fails (because of no text or bad format)
try:
responses = response.json()
# ...
except ValueError:
# no JSON returned
# 3. check that .json() did NOT return an empty dict
if responses:
# ...
# 4. safeguard against malformed data
try:
data = responses[some_key][some_index][...][...]
except (IndexError, KeyError, TypeError):
# data does not have the inner structure you expect
# 5. check if data is actually something useful (truthy in this example)
if data:
# ...
else:
# data is falsy ([], {}, None, 0, '', ...)
