使用 Python 读取 YAML 文件会导致 yaml.composer.ComposerError: expected a single document in the stream

问题描述

我有一个看起来像这样的 yaml 文件

I have a yaml file that looks like

---
level_1: "test"
level_2: 'NetApp, SOFS, ZFS Creation'
request: 341570
---
level_1: "test"
level_2: 'NetApp, SOFS, ZFS Creation'
request: 341569
---
level_1: "test"
level_2: 'NetApp, SOFS, ZFS Creation'
request: 341568

我能够在使用 YAML 的 Perl 中正确读取此内容，但在使用 YAML 的 python 中无法正确读取.它失败并出现错误:

I am able to read this correctly in Perl using YAML but not in python using YAML. It fails with the error:

预期流中有单个文档

程序:

import yaml

stram = open("test", "r")
print yaml.load(stram)

错误:

Traceback (most recent call last):
  File "abcd", line 4, in <module>
    print yaml.load(stram)
  File "/usr/local/pkgs/python-2.6.5/lib/python2.6/site-packages/yaml/__init__.py", line 58, in load
    return loader.get_single_data()
  File "/usr/local/pkgs/python-2.6.5/lib/python2.6/site-packages/yaml/constructor.py", line 42, in get_single_data
    node = self.get_single_node()
  File "/usr/local/pkgs/python-2.6.5/lib/python2.6/site-packages/yaml/composer.py", line 43, in get_single_node
    event.start_mark)
yaml.composer.ComposerError: expected a single document in the stream
  in "test", line 2, column 1
but found another document
  in "test", line 5, column 1

推荐答案

yaml 文档用 --- 分隔，如果任何流(例如文件)包含多个文档，那么你应该使用 yaml.load_all 函数而不是 yaml.load.代码:

The yaml documents are separated by ---, and if any stream (e.g. a file) contains more than one document then you should use the yaml.load_all function rather than yaml.load. The code:

import yaml

stream = open("test", "r")
docs = yaml.load_all(stream)
for doc in docs:
    for k,v in doc.items():
        print k, "->", v
    print "
",

问题中提供的输入文件的结果:

results in for the input file as provided in the question:

request -> 341570
level_1 -> test
level_2 -> NetApp, SOFS, ZFS Creation

request -> 341569
level_1 -> test
level_2 -> NetApp, SOFS, ZFS Creation

request -> 341568
level_1 -> test
level_2 -> NetApp, SOFS, ZFS Creation