Reading YAML file with Python results in yaml.composer.ComposerError: expected a single document in the stream

Question

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 

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

expected a single document in the stream

Program:

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

Error:

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 

Answer 1

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 "\n", 

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