Defaults for didChangeConfiguration Messages

[trajamsmith]

Hey — we're trying to extend the functionality of JupyterLab to include all the features that language servers provide. At present, we're taking a look at server configuration messages. Right now, our onDidChangeConfiguration messages to a few server implementations are working well, but we're having small issues with the yaml-language-server.

We want our settings objects in the JupyterLab editor look something like this:

{
    "language_servers": {
        "pyls": {
            "serverSettings": {
                "pyls.plugins.pydocstyle.enabled": true,
                "pyls.plugins.pyflakes.enabled": false,
                "pyls.plugins.flake8.enabled": true
            }
        },
        "r-languageserver": {
            "serverSettings": {
                "r.lsp.debug": true,
                "r.lsp.diagnostics": false
            }
        },
        "yaml-language-server": {
            "serverSettings": {
                "yaml.format.enable": true,
                "yaml.format.singleQuote": true
            }
        }
    }
}

We'd like to be able to send partial configurations like the above, but I believe the issue we're having is that the onDidChangeConfiguration listener for the YAML server doesn't like partial configurations.

My best guess is that this is because there are no defaults here:

    if (settings.yaml) {
        yamlConfigurationSettings = settings.yaml.schemas;
        yamlShouldValidate = settings.yaml.validate;
        yamlShouldHover = settings.yaml.hover;
        yamlShouldCompletion = settings.yaml.completion;
        customTags = settings.yaml.customTags ? settings.yaml.customTags : [];

        if (settings.yaml.schemaStore) {
            schemaStoreEnabled = settings.yaml.schemaStore.enable;
        }
...

So if we send the configuration settings like I've written them up top, then the server turns off validation, even though my configuration object didn't mention validation.

Is that hunch correct? It's very possible that we're just looking at this the wrong way.

[JPinkney]

Yeah it looks like that's correct, partial configurations don't seem to be working correctly

[trajamsmith]

May I submit a PR for this? This fixes the issue on my local:

    // change this
    if (settings.yaml) {
        yamlConfigurationSettings = settings.yaml.schemas;
        yamlShouldValidate = settings.yaml.validate;
        yamlShouldHover = settings.yaml.hover;
        yamlShouldCompletion = settings.yaml.completion;
        customTags = settings.yaml.customTags ? settings.yaml.customTags : [];

    // to this
    if (settings.yaml) {
        yamlConfigurationSettings = settings.yaml.schemas || yamlConfigurationSettings;
        yamlShouldValidate = settings.yaml.validate || yamlShouldValidate;
        yamlShouldHover = settings.yaml.hover || yamlShouldHover;
        yamlShouldCompletion = settings.yaml.completion || yamlShouldCompletion;
        customTags = settings.yaml.customTags ? settings.yaml.customTags : [];

[JPinkney]

Yeah! A PR would be great!