英文:
How to get all pages into a single result
问题
I have a following API call
this.httpCall.getAllItems().subscribe(results => {for (const each of results) {.....}....});
getAllItems() 是一个基本的HTTP API调用，默认返回10条记录。总数在标头 X-Total-Count 中，例如为65
getAllItems(): Observable<any> {const url = `URL/items?count=true`;return this.http.get(url, { observe: 'response' }));}
总数在 results.headers.get('X-Total-Count'); 中获取。
要获取下一页，需要在API中发送偏移量。因此，要获取所有65条记录，可以这样做
URL/items?limit=10&offset=0URL/items?limit=10&offset=10URL/items?limit=10&offset=20URL/items?limit=10&offset=30URL/items?limit=10&offset=40URL/items?limit=10&offset=50URL/items?limit=10&offset=60
在
URL/items?limit=10&offset=70
时将返回0个。
如何在 this.httpCall.getAllItems().subscribe(results => 中实现上述逻辑，以便将所有结果合并在一起，然后进行for循环？
我了解到switchMap可能对此有所帮助，但我需要一些关于如何在上述逻辑中实现它的帮助。
英文:
I have a following API call
this.httpCall.getAllItems().subscribe(results => {for (const each of results) {.....}....});
The getAllItems() is a basic HTTP API call which returns a result of 10 records by default. The total count comes in header X-Total-Count which for example is 65
getAllItems(): Observable<any> {const url = `URL/items?count=true`;return this.http.get(url, { observe: 'response' }));}
The total count comes in results.headers.get('X-Total-Count');.
To get the next page I need to send offset in API. So, to get all 65 records, I would do
URL/items?limit=10&offset=0URL/items?limit=10&offset=10URL/items?limit=10&offset=20URL/items?limit=10&offset=30URL/items?limit=10&offset=40URL/items?limit=10&offset=50URL/items?limit=10&offset=60
At
URL/items?limit=10&offset=70
There will be 0 return.
How do I implement this above in this.httpCall.getAllItems().subscribe(results => so that I can join all the results in one and then do the for loop continuation?
I read that perhaps switchMap can help here, but I need some help on how to implement it in above logic.
答案1
得分: 1
首先，您需要调用带有偏移量参数的函数以获取项目。
getItems(offset: number): Observable<any> {const url = `URL/items`;return this.http.get(url, { 'limit': 10, 'offset': offset }));}
您还需要调用以获取总记录数的函数。
getNumberOfItems(): Observable<any> {const url = `URL/items?count=true`;return this.http.get(url, { observe: 'response' }));}
然后，订阅它并在循环中使用偏移量作为参数调用getItems函数。
this.httpCall.getNumberOfItems().subscribe(result: any => {let allItems = []const totalCount = result.headers.get('X-Total-Count');const iterations = Math.ceil(totalCount/10)for (let i = 0; i < iterations; i++) {this.httpCall.getItems(i*10).subscribe(listOfItems: any => {allItems.concat(listOfItems)})}});
英文:
First of all you will need a call to get items with offset as a parameter.
getItems(offset : number): Observable<any> {const url = `URL/items`;return this.http.get(url, { 'limit': 10, 'offset': offset }));}
you will also need a call to get the number of total records
getNumberOfItems(): Observable<any> {const url = `URL/items?count=true`;return this.http.get(url, { observe: 'response' }));}
then subscribe to it and call the getItems function with offset as parameter in a for loop
this.httpCall.getNumberOfItems().subscribe(result: any => {let allItems = []const totalCount = result.headers.get('X-Total-Count');const iterations = Math.ceil(totalCount/10)for (let i = 0; i < iterations; i++) {this.httpCall.getItems(i*10).subscribe(listOfItems: any => {allItems.concat(listOfItems)})}});
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