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Capture a request

Source: R/capture.R
capture.data_request.Rd

The first step in evaluating a request is to capture and parse the information it contains. The resulting object has class prequery for those requiring further processing or query for those that don't. A prequery object shows the basic structure of what has been requested by a user in a given galah_call().

Usage

capture(x, ...)

# S3 method for class 'data_request'
capture(x, mint_doi = FALSE, ...)

# S3 method for class 'metadata_request'
capture(x, ...)

# S3 method for class 'files_request'
capture(x, thumbnail = FALSE, ...)

# S3 method for class 'list'
capture(x, ...)

Arguments

x

A _request object to convert to a prequery.

...

Other arguments, currently ignored

mint_doi

Logical: should a DOI be minted for this download? Only applies to type = "occurrences" when atlas chosen is "ALA".

thumbnail

Logical: should thumbnail-size images be returned? Defaults to FALSE, indicating full-size images are required.

Value

Either an object of class prequery when further processing is required; or query when it is not. Both classes are structurally identical, being list-like and containing at the following slots:

  • type: The type of query, serves as a lookup to the corresponding field in show_all(apis)

  • url: Either:

    • a length-1 character giving the API to be queried; or

    • a tibble() containing at least the field url and optionally others

  • request: captures the preceeding _request object (see galah_call())

Details

galah uses an object-based pipeline to convert piped requests into valid queries, and to enact those queries with the specified organisation. Typically, requests open with galah_call() - though request_metadata() and request_files() are also valid - and end with collect(). Under the hood, the sequence of functions is as follows:

capture() → compound() → collapse() → compute() → collect()

capture() is the first of the galah_call() workflow, and it parses the basic structure of a user request, returned as a prequery object. A prequery object shows what has been requested, before those calls are built by compound() and evaluated by collapse(). For simple cases, this gives the same result as running collapse() while the run_checks argument of galah_config() is set to FALSE, but is slightly faster. In complex cases, it is simply a precursor to compound().

See also

To open a piped query, see galah_call(). For alternative operations on _request objects, see compound(), collapse(), compute() or collect().