Question

我正试图围绕链式AngularJS承诺中的错误处理。我知道这种成功/失败的语法：

        .then( function( departure )
        {
            $scope.departure = departure;                               // Response Handler #1
            return travelService.getFlight( departure.flightID );       // Request #2
        }, function( error )
        {
          //handle error
        })

但是，我不知道如何将其应用于这样的链：

var FlightDashboard = function( $scope, user, flightService, weatherService )
{
    travelService
        .getDeparture( user )                                           // Request #1
        .then( function( departure )
        {
            $scope.departure = departure;                               // Response Handler #1
            return travelService.getFlight( departure.flightID );       // Request #2
        })
        .then( function( flight )
        {
            $scope.flight = flight;                                     // Response Handler #2
            return weatherService.getForecast( $scope.departure.date ); // Request #3
        })
        .then( function( weather )
        {
            $scope.weather = weather;                                   // Response Handler #3
        });
};

如果我需要针对这3个请求中的任何一个或全部的错误处理函数，该怎么办？它会是这样的吗？如果确实如此，我需要从错误处理程序返回任何内容吗？

var FlightDashboard = function( $scope, user, flightService, weatherService )
{
    travelService
        .getDeparture( user )                                           // Request #1
        .then( function( departure )
        {
            $scope.departure = departure;                               // Response Handler #1
            return travelService.getFlight( departure.flightID );       // Request #2
        }, function( error )
        {
          //handle request 1 error
        })
        .then( function( flight )
        {
            $scope.flight = flight;                                     // Response Handler #2
            return weatherService.getForecast( $scope.departure.date ); // Request #3
        }, function( error )
        {
          //handle request 2 error
        })
        .then( function( weather )
        {
            $scope.weather = weather;                                   // Response Handler #3
        }, function( error )
        {
          //handle request 3 error
        });
};

Answer 1

是的，就像成功函数一样，错误处理函数也需要返回一个值。 then函数返回的承诺由success或error回调的返回值解决。

这里的一个怪癖是，如果我们在错误回调中执行正常返回，则链中进一步的承诺将始终解析为sucess。如果您希望传播承诺被拒绝承诺链中的承诺，则需要在error回调中返回被拒绝的承诺。像这样：

var FlightDashboard = function( $scope, user, flightService, weatherService )
{
    travelService
        .getDeparture( user )                                           // Request #1
        .then( function( departure )
        {
            $scope.departure = departure;                               // Response Handler #1
            return travelService.getFlight( departure.flightID );       // Request #2
        }, function( error )
        {
            return $q.reject(error)
        })
        .then( function( flight )
        {
            $scope.flight = flight;                                     // Response Handler #2
            return weatherService.getForecast( $scope.departure.date ); // Request #3
        }, function( error )
        {
            return $q.reject(error)
        })
        .then( function( weather )
        {
            $scope.weather = weather;                                   // Response Handler #3
        }, function( error )
        {
            return $q.reject(error)
        });
};

链式AngularJS中的错误处理承诺

1 个答案: