confused by YAML::NodeType::Undefined with yaml-cpp

Question

I have a test yaml file that I am trying to parse using yaml-cpp.

test.yaml

testConfig:
    # this points to additional config files to be parsed
    includes:
        required: "thing1.yaml"
        optional: "thing2.yaml"
    #some extraneous config information 
    foo: 42
    bar: 394
    baz: 8675309

I parse it I get testConfig.Type() returns YAML::NodeType::Map. And this is expected behavior.

Then, I try to parse the includes to get the required or optional values I can't iterate because includes.Type() returns YAML::NodeType::Undefined. I'm really new to yaml and to yaml-cpp so any help showing me where I am going wrong would be appreciated.

parsing code:

{includes and other such nonsense} 
            .
            .
            .
YAML::Node configRoot = YAML::LoadFile(path.c_str() );
if( configRoot.IsNull() )
{   
    SYSTEM_LOG_ERROR("Failed to load the config file: %s.",
                    path.c_str());
    return false;
}   

YAML::Node includes = configRoot["includes"];
/*  ^^^^^^^^^^^^^^^
 * I believe that here lies the issue as includes is undefined and
 * therefore I cannot iterate over it.
 */
for( auto it = include.begin(); it != include.end(); ++it )
{   
    // do some fantastically brilliant CS voodoo!
}
            .
            .
            .
{ more C++ craziness to follow }

SOLUTION: I removed the unnecessary top level configTest so that I could parse the includes as I needed.

There is no need to put quotes around `thingX.yaml` in your YAML file — Anthon, Aug 24 '16 at 15:17
@Anthon Thanks for the info... I am used to json where it seems that quotes are needed for virtually everything. — CompSciGuy139, Aug 24 '16 at 15:52

score 2 · Answer 1 · answered Aug 24 '16 at 14:58

Well, your top-level YAML document does indeed not include a key named includes. It only contains a key named testConfig. You should access that first:

// ...
YAML::Node configRoot = YAML::LoadFile(path.c_str())["testConfig"];
// ...

Or, if you want to explicitly check if testConfig exists:

// ...
YAML::Node configRoot = YAML::LoadFile(path.c_str());
// do check her as in your code
YAML:Node testConfig = configRoot["testConfig"];
// check if testConfig is a mapping here
YAML::Node includes = testConfig["includes"];
// ...

score 1 · Accepted Answer · answered Aug 24 '16 at 14:59

1

You're looking at configRoot["includes"], but the top level key in your map is testConfig. Use configRoot["testConfig"] instead.

answered Aug 24 '16 at 14:59

Jesse Beder

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I just found this and was about to comment! Thanks for the quick response. I just removed that superfluous top level testConfig. – CompSciGuy139 Aug 24 '16 at 15:24

confused by YAML::NodeType::Undefined with yaml-cpp

2 Answers2