datashield.connections_default {DSI}

Set or get the default list of DSConnection objects in the analytic environment

Description

By default if there is only one set of DSConnection-class objects that is available for analysis, all DataSHIELD client-side functions will use that full set of DSConnections unless the 'datasources=' argument has been set and specifies that a particular subset of those DSConnections should be used instead. The correct identification of the full single set of opals is based on the datashield.connections_find function. To illustrate, if the single set of Opals is called 'study.opals' and consists of six servers numbered studies[1] to studies[6] then all client-side functions will use data from all six of these 'studies' unless, say, datasources=studies[c(2,5)] is declared and only data from the second and fifth studies will then be used. On the other hand, if there is more than one set of DSConnections in the analytic environment client-side functions will be unable to determine which set to use. The function datashield.connections_find has therefore been written so that if one of the DSConnection sets is called 'default.connections' then that set - i.e. 'default.connections' - will be selected by default by all DataSHIELD client-side functions. If there is more than one set of DSConnections in the analytic environment and NONE of these is called 'default.connections', the function datashield.connections_find will fail. Therefore datashield.connections_default copies the provided set of DSConnections as 'default.connections'. This set will then be selected by default by all client-side functions, unless it is deleted and an alternative set of DSConnections is copied and named 'default.connections'. Regardless how many sets of DSConnections exist and regardless whether any of them may be called 'default.connections', the 'datasources=' argument overrides the defaults and allows the user to base his/her analysis on any set of DSConnections and any subset of those DSConnections.

Usage

datashield.connections_default(
  name = NULL,
  env = getOption("datashield.env", globalenv())
)

Arguments

name

Symbol name that identifies the set of DSConnection-class objects to be used by default. If not provided, the 'default.connections' variable value is returned.

env

The environment where to search for the connection symbols. Try to get it from the 'datashield.env' option, with default to the Global Environment.

Value

The 'default.connections' value from the analytic environment or NULL if the 'default.connections' symbol is not defined.

See Also

Other Connections management: datashield.connections_find(), datashield.connections()