rstac (version 0.9.1-5)

ext_query: Extension functions

Description

The ext_query() is the exported function of the STAC API query extension. It can be used after a call to stac_search() function. It allows that additional fields and operators other than those defined in stac_search() function be used to make a complex filter.

The function accepts multiple filter criteria. Each filter entry is an expression formed by <field> <operator> <value>, where <field> refers to a valid item property. Supported <fields> depends on STAC API service implementation. The users must rely on service providers' documentation to know which properties can be used by this extension.

The ext_query() function allows the following <operators>

• == corresponds to 'eq'

• != corresponds to 'neq'

• < corresponds to 'lt'

• <= corresponds to 'lte'

• > corresponds to 'gt'

• >= corresponds to 'gte'

• \%startsWith\% corresponds to 'startsWith' and implements a string prefix search operator.

• \%endsWith\% corresponds to 'endsWith' and implements a string suffix search operator.

• \%contains\%: corresponds to 'contains' and implements a string infix search operator.

• \%in\%: corresponds to 'in' and implements a vector search operator.

Besides this function, the following S3 generic methods were implemented to get things done for this extension:

• The endpoint() for subclass ext_query

• The before_request() for subclass ext_query

• The after_response() for subclass ext_query

See source file ext_query.R for an example on how implement new extensions.

Usage

ext_query(q, ...)

Value

A RSTACQuery object with the subclass ext_query containing all request parameters to be passed to post_request() function.

Arguments

q

a RSTACQuery object expressing a STAC query criteria.

...

entries with format <field> <operator> <value>.

See Also

stac_search(), post_request(), endpoint(), before_request(), after_response(), content_response()

Examples

# \donttest{
stac("https://brazildatacube.dpi.inpe.br/stac/") %>%
  stac_search(collections = "CB4_64_16D_STK-1") %>%
  ext_query("bdc:tile" %in% "022024") %>%
  post_request()
# }