为什么python字典是空的？

Question

I have a function that runs through a list and then loads a dictionary. It prints out fine within the function but the return dict is empty?

 95 def getAttachmentDict(messageIds):
 96     messageTable = defaultdict(list)
 97     for id in messageIds:
 98         uri = "/message/" + id
 99         res = getMessages(uri)
100         doc = xml.dom.minidom.parse(res)
101         idUrl = doc.getElementsByTagName("url")
102         alist = []
103         for i in idUrl:
104             urlData = i.childNodes[0].nodeValue
105             alist.append(urlData)
106         messageTable[id] = alist
107     print "\n"
108     for key, value in messageTable.items():
109         print "Message ID: " + key 
110         print "\n".join(value) 
111     return messageTable

169         getAttachmentDict(messageIds)
170         pdb.set_trace()
171         print messageTable

Message ID: MyUHRnzm7AXkFmiKocUjzn config-safety-report.html Message ID: RqfljNnyz63bBpGLtL4B2D individual-report.csv

/Work/ftpTool/acquire.py(171)main() -> print messageTable (Pdb) n {}

Answer 1

You're not doing anything with the return value. This is just printing some other variable you've called messageTable

169         getAttachmentDict(messageIds)
170         pdb.set_trace()
171         print messageTable

try this instead

169         messageTable = getAttachmentDict(messageIds)
170         pdb.set_trace()
171         print messageTable

Answer 2

When you call getAttachmentDict() , you need to assign the result to a name (which could be messageTable , or any other name you want to use). For example:

169         messageTable = getAttachmentDict(messageIds)
170         pdb.set_trace()
171         print messageTable