httpToKey(httpRequest: HttpRequest<any>) {
const key = httpRequest.method + '@' + httpRequest.urlWithParams + '@' + hash(httpRequest.params, hashOptions) + '@' + hash(httpRequest.body, hashOptions)
return key
}
intercept(httpRequest: HttpRequest<unknown>, next: HttpHandler): Observable<HttpEvent<unknown>> {
//console.log(httpRequest)
//console.log('has', httpRequest.headers.has(CachingHeaders.NoCache))
//console.log('value', httpRequest.headers.get(CachingHeaders.NoCache))
if (httpRequest.headers.get(CachingHeaders.NoCache) !== null) {
//console.log('using cache')
const headers = httpRequest.headers.delete(CachingHeaders.NoCache)
const newRequest = httpRequest.clone({
headers: headers
})
return next.handle(newRequest);
}
/*
// Also leave scope of resetting already cached data for a URI
if (httpRequest.headers.get("reset-cache")) {
this.cachedData.delete(httpRequest.urlWithParams);
}
*/
// Checked if there is cached data for this URI
const key = this.httpToKey(httpRequest)
const lastResponse = this.cachedData.get(key);
if (lastResponse) {
// In case of parallel requests to same URI,
// return the request already in progress
// otherwise return the last cached data
//console.info('http cache interceptor hit cache', key)
return (lastResponse instanceof Observable)
? lastResponse : of(lastResponse.clone());
}
//console.info('http cache interceptor', key)
// If the request of going through for first time
// then let the request proceed and cache the response
const requestHandle = next.handle(httpRequest).pipe(
tap((stateEvent: any) => {
if (stateEvent instanceof HttpResponse) {
this.cachedData.set(
key,
stateEvent.clone()
);
}
})
)
// Meanwhile cache the request Observable to handle parallel request
//this.cachedData.set(key, requestHandle);
return requestHandle;
