Question

如果是这样的话：

getCol = (colId)->
   dfrd = $q.defer()
   if colId == "bacon"
       dfrd.reject()
   else
       dfrd.resolve colId
   dfrd.promise


getCols = (columns)->
   $q.all(_.map(columns, (cs)-> getCol(cs)))


getCols(['eggs','juice']).then (cols)->
   console.log cols                    # works



getCols(['eggs','juice','bacon']).then (cols)->
   console.log cols                  # not even getting here

所以，在getCols()中，我怎样才能只返回那些已经解决的承诺？

Answer 1

$q.all仅用于解决all of the promises you pass it解决后的问题。比如，只有在所有4个小部件都已加载后才显示您的仪表板，这样做很有用。

如果您不想要这种行为，也就是说，您希望尝试显示可以成功解析的列数，那么您必须使用其他方法。

loadedColumns = []

getCols = (columns) ->
  for col in columns
    willAdd = addColumn(col) # add column needs to store columns in the "loadedColumns" area, then resolve
    willAdd.then buildUI
    willAdd.catch logError


# Because this method is debounced, it'll fire the first time there is 50 ms of idleness
buildUI = _.debounce ->
  // Construct your UI out of "loadedColumns"
, 50

$ q.all - 只接受那些解决的问题

1 个答案: