ext_query: Query extension

In rstac: Client Library for SpatioTemporal Asset Catalog

Query extension

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 the 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 before_request() for subclass ext_query

• The after_response() for subclass ext_query

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

Usage

ext_query(q, ...)

Arguments

q	a rstac_query object expressing a STAC query criteria.
...	entries with format ⁠<field> <operator> <value>⁠.

Value

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

See Also

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

Examples

## Not run: 
 stac("https://brazildatacube.dpi.inpe.br/stac/") %>%
   stac_search(collections = "CB4-16D-2") %>%
   ext_query("bdc:tile" %in% "007004") %>%
   post_request()

## End(Not run)

rstac documentation built on Sept. 11, 2024, 7:03 p.m.