How do I avoid unwrap when converting a vector of Options or Results to only the successful values?

I want to ignore all Err values

Since Result implements IntoIterator, you can convert your Vec into an iterator (which will be an iterator of iterators) and then flatten it:

• Iterator::flatten:

  vec.into_iter().flatten().collect()
  

• Iterator::flat_map:

  vec.into_iter().flat_map(|e| e).collect()
  

These methods also work for Option, which also implements IntoIterator.

You could also convert the Result into an Option and use Iterator::filter_map:

vec.into_iter().filter_map(|e| e.ok()).collect()