What's the correct way to handle missing data?

[reimund]

Whenever one of my find-commands fails and gives me "(find) no results for ____" Osmosis seems to abort the chain.

I tried catching the error with .error, but my subsequent find/data commands are still ignored.

What's the correct way to make Osmosis continue, ignoring the missing data?

I'm doing something like:

osmosis
    .get(url) 
    .find(...)
        .set(...)
    .follow(...)
        .find(...)
            .set(...)
        .find(...) // This selector does not always resolve
            .set(...})
        .find(...) // This doesn't seem to run if the above fails
            .set(...)
    .follow('a@href') // Neither does this
        .find(...)
            .set(..)
    .data(function(stuff) {
        // And I never get here :(
    })
    .done(function() {
        // But I do get here...
    })

[reimund]

Seems like calling next in a then block after the failing set does the trick.

Eg:

osmosis
    .get(url) 
    .find(...)
        .set(...)
    .follow(...)
        .find(...)
            .set(...)
        .find(...) // This selector does not always resolve
            .set(...})
        .then(context, data, next) {
            next(context, data);
        }
        .find(...)
            .set(...)
    .follow('a@href')
        .find(...)
            .set(..)
    .data(function(stuff) {
        ...
    })
    .done(function() {
        ..
    })

[rchipka]

There isn't an official way to handle missing data. By default, Osmosis assumes that if one link in the chain fails, any subsequent commands will fail. This obviously isn't always the case. I'll be working on a solution to this.

[rchipka]

The next version of Osmosis is planned to have .do(). This command will allow one or more nested instances to run from the current context and return to the next command regardless of whether any of the nested instances failed.

osmosis.get(url)
...
.do(
    osmosis... ,
    osmosis... ,
    osmosis...
)
...

[rchipka]

Supported in 0.1.0