DigestCache class
IDigestCache is an internal service used by SPHttpClient to maintain a cache of request digests for each SPWeb URL. A request digest is a security token that the SharePoint server requires for for any REST write operation, specified via the "X-RequestDigest" HTTP header. It is obtained by calling the "/_api/contextinfo" REST endpoint, and expires after a server configurable amount of time.
For more information, see the MSDN article "Complete basic operations using SharePoint 2013 REST endpoints"
Constructors
| (constructor)(service |
Constructs a new instance of the |
Properties
| service |
The service key for IDigestCache. |
Methods
| add |
Inserts a specific request digest value into the cache. Normally this is unnecessary because the framework will automatically issue a REST request to fetch the digest when necessary; however, in advanced scenarios addDigestToCache() can be used to avoid the overhead of the REST call. |
| clear |
Clears all values from the cache. |
| clear |
Clears the cached digest for the specified SPWeb URL. This operation is useful e.g. if an error indicates that a digest was invalidated prior to its expiration time. |
| fetch |
Returns a digest string for the specified SPWeb URL. If the cache already contains a usable value, the promise is fulfilled immediately. Otherwise, the promise will be pending and resolve after an HTTP request obtains the digest, which will be added to the cache. |
Constructor Details
(constructor)(serviceScope)
Constructs a new instance of the DigestCache class
constructor(serviceScope: ServiceScope);Parameters
- serviceScope
- ServiceScope
Property Details
serviceKey
The service key for IDigestCache.
static readonly serviceKey: ServiceKey<IDigestCache>;Property Value
Method Details
addDigestToCache(webUrl, digestValue, expirationTimestamp)
Inserts a specific request digest value into the cache. Normally this is unnecessary because the framework will automatically issue a REST request to fetch the digest when necessary; however, in advanced scenarios addDigestToCache() can be used to avoid the overhead of the REST call.
addDigestToCache(webUrl: string, digestValue: string, expirationTimestamp: number): void;Parameters
- webUrl
-
string
The URL of the SPWeb that the API call will be issued to. This may be a server-relative or absolute URL.
- digestValue
-
string
The digest value, which is an opaque that must be generated by the SharePoint server. The syntax will look something like this: "0x0B85...2EAC,29 Jan 2016 01:23:45 -0000"
- expirationTimestamp
-
number
A future point in time, as measured by performance.now(), after which the digest value will no longer be valid. NOTE: The expirationTime is a DOMHighResTimeStamp value whose units are fractional milliseconds; for example, to specify an expiration "5 seconds from right now", use performance.now()+5000.
Returns
void
clearAllDigests()
Clears all values from the cache.
clearAllDigests(): void;Returns
void
clearDigest(webUrl)
Clears the cached digest for the specified SPWeb URL. This operation is useful e.g. if an error indicates that a digest was invalidated prior to its expiration time.
clearDigest(webUrl: string): boolean;Parameters
- webUrl
-
string
The URL of the SPWeb whose digest should be cleared. This may be a server-relative or absolute URL.
Returns
boolean
Returns true if a cache entry was found and deleted; false otherwise.
fetchDigest(webUrl)
Returns a digest string for the specified SPWeb URL. If the cache already contains a usable value, the promise is fulfilled immediately. Otherwise, the promise will be pending and resolve after an HTTP request obtains the digest, which will be added to the cache.
fetchDigest(webUrl: string): Promise<string>;Parameters
- webUrl
-
string
The URL of the SPWeb that the API call will be issued to. This may be a server-relative or absolute URL.
Returns
Promise<string>
A promise that is fulfilled with the digest value.