Specs

build_absolute_url(binary(), binary()) :: binary()

A helper function which joins relative url with a base URL

Specs

build_absolute_urls([binary()], binary()) :: [binary()]

A helper function which joins relative url with a base URL for a list

Specs

get_modules_from_applications() :: [module()]

Specs

get_settings(setting_name, spider_name, default) :: result
when setting_name: atom(), spider_name: atom(), default: term(), result: term()

A helper which allows to extract a given setting.

Returned value is a result of intersection of the global settings and settings defined as settings_override inside the spider. Settings defined on spider are taking precedence over the global settings defined in the config.

Specs

list_spiders() :: [module()]

Returns a list of known modules which implements Crawly.Spider behaviour

Specs

pipe(pipelines, item, state) :: result
when pipelines: [Crawly.Pipeline.t()],
     item: map(),
     state: map(),
     result: {new_item | false, new_state},
     new_item: map(),
     new_state: map()

Pipeline/Middleware helper

Executes a given list of pipelines on the given item, mimics filtermap behavior. Takes an item and state and passes it through a list of modules which implements a pipeline behavior, executing the pipeline's Crawly.Pipeline.run/3 function.

The pipe function must either return a boolean (false), or an updated item.

If false is returned by a pipeline, the item is dropped. It will not be processed by any descendant pipelines.

In case of a pipeline crash, the pipeline will be skipped and the item will be passed on to descendant pipelines.

The state variable is used to persist the information accross multiple items.

Usage in Tests

The Crawly.Utils.pipe/3 helper can be used in pipeline testing to simulate a set of middlewares/pipelines.

Internally, this function is used for both middlewares and pipelines. Hence, you can use it for testing modules that implement the Crawly.Pipeline behaviour.

For example, one can test that a given item is manipulated by a pipeline as so:

item = %{my: "item"}
state = %{}
pipelines = [ MyCustomPipelineOrMiddleware ]
{new_item, new_state} = Crawly.Utils.pipe(pipelines, item, state)

Specs

request_from_url(binary()) :: Crawly.Request.t()

A helper function which returns a Request structure for the given URL

Specs

requests_from_urls([binary()]) :: [Crawly.Request.t()]

A helper function which converts a list of URLS into a requests list.

Specs

send_after(pid(), term(), pos_integer()) :: reference()

A wrapper over Process.send after This wrapper should be used instead of Process.send_after, so it's possible to mock the last one. To avoid race conditions on worker's testing.