FileDownload
Hierarchy
- HttpCrawler<FileDownloadCrawlingContext>
- FileDownload
Index
Constructors
constructor
Parameters
options: FileDownloadOptions<any, any> = {}
Returns FileDownload
Properties
optionalautoscaledPool
A reference to the underlying AutoscaledPool class that manages the concurrency of the crawler.
NOTE: This property is only initialized after calling the
crawler.run()
function. We can use it to change the concurrency settings on the fly, to pause the crawler by callingautoscaledPool.pause()
or to abort it by callingautoscaledPool.abort()
.
readonlyconfig
hasFinishedBefore
readonlylog
optionalproxyConfiguration
A reference to the underlying ProxyConfiguration class that manages the crawler's proxies. Only available if used by the crawler.
optionalrequestList
A reference to the underlying RequestList class that manages the crawler's requests. Only available if used by the crawler.
optionalrequestQueue
Dynamic queue of URLs to be processed. This is useful for recursive crawling of websites. A reference to the underlying RequestQueue class that manages the crawler's requests. Only available if used by the crawler.
readonlyrouter
Default Router instance that will be used if we don't specify any requestHandler
.
See router.addHandler()
and router.addDefaultHandler()
.
running
optionalsessionPool
A reference to the underlying SessionPool class that manages the crawler's sessions. Only available if used by the crawler.
readonlystats
A reference to the underlying Statistics class that collects and logs run statistics for requests.
Methods
addRequests
Adds requests to the queue in batches. By default, it will resolve after the initial batch is added, and continue adding the rest in background. You can configure the batch size via
batchSize
option and the sleep time in between the batches viawaitBetweenBatchesMillis
. If you want to wait for all batches to be added to the queue, you can use thewaitForAllRequestsToBeAdded
promise you get in the response object.This is an alias for calling
addRequestsBatched()
on the implicitRequestQueue
for this crawler instance.Parameters
requests: (string | Source)[]
The requests to add
options: CrawlerAddRequestsOptions = {}
Options for the request queue
Returns Promise<CrawlerAddRequestsResult>
exportData
Retrieves all the data from the default crawler Dataset and exports them to the specified format. Supported formats are currently 'json' and 'csv', and will be inferred from the
path
automatically.Type parameters
- Data
Parameters
path: string
optionalformat: json | csv
optionaloptions: DatasetExportOptions
Returns Promise<Data[]>
getData
Retrieves data from the default crawler Dataset by calling Dataset.getData.
Parameters
rest...args: [options: DatasetDataOptions]
Returns Promise<DatasetContent<Dictionary>>
getDataset
getRequestQueue
Returns Promise<RequestProvider>
pushData
Pushes data to the specified Dataset, or the default crawler Dataset by calling Dataset.pushData.
Parameters
data: Dictionary | Dictionary[]
optionaldatasetIdOrName: string
Returns Promise<void>
run
Runs the crawler. Returns a promise that gets resolved once all the requests are processed. We can use the
requests
parameter to enqueue the initial requests - it is a shortcut for runningcrawler.addRequests()
before thecrawler.run()
.Parameters
optionalrequests: (string | Request<Dictionary> | RequestOptions<Dictionary>)[]
The requests to add
optionaloptions: CrawlerRunOptions
Options for the request queue
Returns Promise<FinalStatistics>
setStatusMessage
This method is periodically called by the crawler, every
statusMessageLoggingInterval
seconds.Parameters
message: string
options: SetStatusMessageOptions = {}
Returns Promise<void>
use
EXPERIMENTAL Function for attaching CrawlerExtensions such as the Unblockers.
Parameters
extension: CrawlerExtension
Crawler extension that overrides the crawler configuration.
Returns void
useState
Type parameters
- State: Dictionary = Dictionary
Parameters
defaultValue: State = ...
Returns Promise<State>
Provides a framework for downloading files in parallel using plain HTTP requests. The URLs to download are fed either from a static list of URLs or they can be added on the fly from another crawler.
Since
FileDownload
uses raw HTTP requests to download the files, it is very fast and bandwidth-efficient. However, it doesn't parse the content - if you need to e.g. extract data from the downloaded files, you might need to use CheerioCrawler, PuppeteerCrawler or PlaywrightCrawler instead.FileCrawler
downloads each URL using a plain HTTP request and then invokes the user-provided FileDownloadOptions.requestHandler where the user can specify what to do with the downloaded data.The source URLs are represented using Request objects that are fed from RequestList or RequestQueue instances provided by the FileDownloadOptions.requestList or FileDownloadOptions.requestQueue constructor options, respectively.
If both FileDownloadOptions.requestList and FileDownloadOptions.requestQueue are used, the instance first processes URLs from the RequestList and automatically enqueues all of them to RequestQueue before it starts their processing. This ensures that a single URL is not crawled multiple times.
The crawler finishes when there are no more Request objects to crawl.
We can use the
preNavigationHooks
to adjustgotOptions
:New requests are only dispatched when there is enough free CPU and memory available, using the functionality provided by the AutoscaledPool class. All AutoscaledPool configuration options can be passed to the
autoscaledPoolOptions
parameter of theFileCrawler
constructor. For user convenience, theminConcurrency
andmaxConcurrency
AutoscaledPool options are available directly in theFileCrawler
constructor.Example usage