Why does my jQuery getJSON call (within Office.js (Excel js add-in)) return an error?

问题

This javascript within an Office js add-in always fails when making a get request:

function update() {
    Excel.run(function (ctx) {

        return ctx.sync()
            .then(function () {

                var company = $('#company').val();
                var environment = $('#environment').val();
                var apiUrl = "https://localhost:44321/api/Country";
                var params = "company=" + company + "&environment=" + environment;

                $.getJSON(apiUrl, params)
                    .done(function (result) {
                        showNotification(result.length);
                    })
                    .fail(function (xhr, status, error) {
                        //showNotification(error.statusText);
                        showNotification(error.length);
                    });
            });
    }).catch(function (error) {
        showNotification(error);
    });
}

I can see the json being returned successfully within Fiddler and JSONLint says the json is valid. Here it is:

[{"country":"UK","countryLongName":"United Kingdom","currency":"GBP"}]

I'm running on localhost with https, and have the following AppDomains in my manifest (belt and braces):

<AppDomain>https://localhost:44321/api/Country</AppDomain>
<AppDomain>https://localhost:44321</AppDomain>
<AppDomain>https://localhost</AppDomain>

However, getJSON.fail() is always invoked, with the following parameters:

xhr.responseJSON: undefined
xhr.statusText: "error"
status: "error"
error: ""

Why does getJSON always fail?

Further edit I've tried this js instead...

                $.ajax({
                    url: apiUrl,
                    dataType: 'json',
                    async: false,
                    data: params,
                    success: function (data) {
                        showNotification(data);
                    },
                    error: function (msg) {
                        showNotification('error : ' + msg.d);
                    }
                });

...and now the error function is being invoked with the following parameters:

msg.responseJSON: undefined
msg.status: 0
msg.statusText: "NetworkError"

回答1:

It's all to do with CORS, I found the solution in rick-strahl's post:

https://weblog.west-wind.com/posts/2016/Sep/26/ASPNET-Core-and-CORS-Gotchas#ApplythePolicy

Specifically, "UseCors() has to be called before UseMvc() Make sure you declare the CORS functionality before MVC so the middleware fires before the MVC pipeline gets control and terminates the request."

来源：https://stackoverflow.com/questions/49260161/why-does-my-jquery-getjson-call-within-office-js-excel-js-add-in-return-an-e

标签

javascript

jquery

office-js