[英]How to make Javascript wait for a Promise before sending a request?
I know there are many questions and answers based on Promise, but what I want to do is to retrieve some data with axios (to a microservice) and then to use this data in order to send another request (to a different microservice).我知道有很多基于 Promise 的问题和答案,但我想要做的是用 axios 检索一些数据(到微服务),然后使用这些数据发送另一个请求(到不同的微服务)。
Somehow, I figured out how to set my request:不知何故,我想出了如何设置我的请求:
screenshot from console with the request right before axios call在 axios 调用之前带有请求的控制台屏幕截图
The problem is that in backend I have only first two clauses.问题是在后端我只有前两个子句。 I think this is because I have used async/await in order to successfully avoid Promise and get the actual result/class.我认为这是因为我使用了 async/await 来成功避免 Promise 并获得实际结果/类。 What I meant is that, maybe the request is sent before the promise is fulfilled, but how do I correctly get the request in console?我的意思是,也许请求是在承诺完成之前发送的,但是如何在控制台中正确获取请求?
I am newbie into Javascript, so any helping hand is welcome.我是 Javascript 的新手,所以欢迎任何帮助。
EDIT:编辑:
Here is my code:这是我的代码:
getServicesList = async (instanceIds) => {
return await FlowsInventoryAPI.searchServices(instanceIds, this.props.salesline, this.props.environment, this.props.sources, this.props.targets)
.then((response) => {
return response;
})
.catch((error) => {
Toastr.error(ResponseErrorProvider.getError(error));
if (ResponseErrorProvider.isUnauthorized(error)) {
Toastr.error(error.response.data.message);
this.props.onLogout();
}
});
}
The above one is the first call I've talked about.上面是我谈到的第一个电话。
buildSearchObject = (size, page, status) => {
let interval = TimestampUtils.getInterval(this.props.logsTimeInterval);
let from = interval.from * 1000;
let to = interval.to * 1000;
return {
fromMillis: from,
toMillis: to,
size: size,
page: page,
salesline: this.props.salesline,
environment: this.props.environment,
routes: this.props.routes,
sources: this.props.sources,
targets: this.props.targets,
customFilters: [...this.props.filters.values(), ...this.getEnabledAdvancedFilters().values()],
status: status === LogStatus.ALL ? "" : status,
sortFieldName: this.props.sortColumn,
order: this.props.sortOrder,
searchFilter: this.props.searchFilter,
searchFilterOperator: this.props.searchFilterOperator,
applications: this.props.applications,
openedStores: this.props.openedStores,
servicesPromise: this.state.servicesList // here is the promise
}
};
searchLogs = (size, page, status, callback) => {
loadingService.showLoadingModal("loadingLogsPage", this.props.location.pathname);
let searchObject = this.buildSearchObject(size, page, status);
ElasticSearchApi.search(searchObject, this.props.token)
.then(response => {
callback(response);
})
.catch((error) => {
loadingService.hideLoadingModal("loadingLogsPage", this.props.location.pathname);
Toastr.error(ResponseErrorProvider.getError(error));
if (ResponseErrorProvider.isUnauthorized(error)) {
Toastr.error(error.response.data.message);
this.props.onLogout();
}
});
};
I have the second call in last paragraph which calls the buildSearchObject method which contains our promise.我在最后一段中进行了第二次调用,它调用了包含我们的承诺的 buildSearchObject 方法。 As I told you I figured out how to send it as value, but I think that because of "asynchronicity" maybe my promise is not ready yet in the moment when second call is called, this is why my code has the promise in state.正如我告诉你的,我想出了如何将它作为值发送,但我认为由于“异步性”,可能我的承诺在第二次调用的那一刻还没有准备好,这就是为什么我的代码有状态的承诺。
EDIT 2:编辑2:
constructor(props) {
super(props);
this.ongoingRequestId = undefined;
this.ongoingRequests = new Map();
this.state = {
servicesList: this.getServicesList(this.getInstanceIds())
}
}
Here is my constructor, where I create my this.state.servicesList.这是我的构造函数,我在其中创建了 this.state.servicesList。
Some advice:一些忠告:
For instance, transform this:例如,转换这个:
FlowsInventoryAPI.searchServices(/* params */)
.then((response) => /* response code */)
.catch((error) => /* error code */)
to:到:
try {
const response = await FlowsInventoryAPI.searchServices(/* params */);
/* response code */
} catch (error) {
/* error code */
}
this.getServicesList
, because you cannot wait for an asynchronous operation (like getServicesList
) inside a constructor.不要像调用this.getServicesList
那样使构造函数异步,因为您不能在构造函数中等待异步操作(如getServicesList
)。 Use instead a static async method.改用静态异步方法。For instance, transform this:例如,转换这个:
class SomeObject extends Something {
constructor(props) {
super(props);
this.ongoingRequestId = undefined;
this.ongoingRequests = new Map();
this.state = {
servicesList: this.getServicesList(this.getInstanceIds())
}
}
}
to:到:
class SomeObject extends Something {
constructor(props) {
super(props);
this.ongoingRequestId = undefined;
this.ongoingRequests = new Map();
this.state = { servicesList: null };
}
async init() {
this.state.servicesList = await this.getServicesList(this.getInstanceIds());
}
static async create(props) {
const someObject = new SomeObject(props);
await someObject.init();
return someObject;
}
}
Instead of calling const object = new SomeObject(props);
而不是调用const object = new SomeObject(props);
, do const object = await SomeObject.create(props);
, 做const object = await SomeObject.create(props);
You will need to use await
keyword to wait for a promise response before continuing.在继续之前,您需要使用await
关键字来等待承诺响应。
// 1. Wait for create or update the customer before continuing
const customerId = await updateOrCreateCustomer(customerData);
// 2. Register sale, with customer created in previous section
const customerSale = sale(paymentMethod, customerId);
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