Python和PYAML - yaml.scanner.ScannerError：不允许在此处映射值

Question

我在64位的Ubuntu系统上，使用的是Python 2.7和PyYAML-3.10这个库。

下面是我的yaml文件：

host:localhost
username:root
password:test
database:test
operations_database:operations
treeroot:
    branch1:
        name: Node 1
        branch1-1:
            name: Node 1-1
    branch2:
        name: Node 2
        branch2-1:
            name: Node 2-1

当我运行下面的代码时，出现了一个错误。不过如果我把树根（treeroot）上面的那些行去掉，代码就能正常运行：

from yaml import load, dump
try:
    from yaml import CLoader as Loader, CDumper as Dumper
except ImportError:
    from yaml import Loader, Dumper
f=open('amazon.yaml')  
data = load(f, Loader=Loader) 

Traceback (most recent call last):
  File "/home/ubuntu/workspace/Amazon-Products-Crawler-1/config_files/test_yaml.py", line 10, in <module>
    data = load(f, Loader=Loader) 
  File "/usr/local/lib/python2.7/dist-packages/yaml/__init__.py", line 71, in load
    return loader.get_single_data()
  File "/usr/local/lib/python2.7/dist-packages/yaml/constructor.py", line 37, in get_single_data
    node = self.get_single_node()
  File "/usr/local/lib/python2.7/dist-packages/yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "/usr/local/lib/python2.7/dist-packages/yaml/composer.py", line 58, in compose_document
    self.get_event()
  File "/usr/local/lib/python2.7/dist-packages/yaml/parser.py", line 118, in get_event
    self.current_event = self.state()
  File "/usr/local/lib/python2.7/dist-packages/yaml/parser.py", line 193, in parse_document_end
    token = self.peek_token()
  File "/usr/local/lib/python2.7/dist-packages/yaml/scanner.py", line 128, in peek_token
    self.fetch_more_tokens()
  File "/usr/local/lib/python2.7/dist-packages/yaml/scanner.py", line 220, in fetch_more_tokens
    return self.fetch_value()
  File "/usr/local/lib/python2.7/dist-packages/yaml/scanner.py", line 580, in fetch_value
    self.get_mark())
yaml.scanner.ScannerError: mapping values are not allowed here
  in "amazon.yaml", line 6, column 9

Answer 1

如果有人来到这里，格式和空格都没问题，但错误还是存在。

检查一下版本后面有没有冒号！(我自己都觉得傻)

错误信息：

version '3.7'

services:
  rabbitmq3:
    image: rabbitmq:3-management

修复方法：

version: '3.7'

services:
  rabbitmq3:
    image: rabbitmq:3-management

Answer 2

如果你来到这里，发现即使在冒号后面加了空格，还是会出现这个错误

你也可能会因为从某些格式化的来源复制了yaml文本而遇到这个错误（对我来说，是从Slack消息中复制的）。这样做会悄悄地替换成一些标准的YAML读取器无法识别的非ASCII字符，但它们看起来是一样的。

解决办法是只从原始的、ASCII格式的来源复制。

Answer 3

试着在冒号后面加个空格。