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A TealDataConnection class of objects

TealDataConnection.Rd

[Stable]

Objects of this class store the connection to a data source. It can be a database or server connection.

Methods

Public methods

Method new()

Create a new TealDataConnection object

Usage 

TealDataConnection$new(
  open_fun = NULL,
  close_fun = NULL,
  ping_fun = NULL,
  if_conn_obj = FALSE
)

Arguments

open_fun

(CallableFunction) function to open connection

close_fun

(CallableFunction) function to close connection

ping_fun

(CallableFunction) function to ping connection

if_conn_obj

optional, (logical) whether to store conn object returned from opening connection

Returns

new TealDataConnection object

Method finalize()

Finalize method closing the connection.

Usage 

TealDataConnection$finalize()

Returns

NULL

Method is_opened()

If connection is opened

If open connection has been successfully evaluated

Usage 

TealDataConnection$is_opened()

Returns

(logical) if connection is open

Method is_failed()

Check if connection has not failed.

Usage 

TealDataConnection$is_failed()

Returns

(logical) TRUE if connection failed, else FALSE

Method launch()

Run simple application that uses its ui and server fields to open the connection.

Useful for debugging

Usage 

TealDataConnection$launch()

Returns

An object that represents the app

Method open()

Open the connection.

Note that if the connection is already opened then it does nothing.

Usage 

TealDataConnection$open(args = NULL, silent = FALSE, try = FALSE)

Arguments

args

(NULL or named list) additional arguments not set up previously

silent

(logical) whether convert all "missing function" errors to messages

try

(logical) whether perform function evaluation inside try clause

Returns

returns self if successful or if connection has been already opened. If open_fun fails, app returns an error in form of shinyjs::alert (if try = TRUE) or breaks the app (if try = FALSE)

Method get_conn()

Get internal connection object

Usage 

TealDataConnection$get_conn()

Returns

connection object

Method get_open_call()

Get executed open connection call

Usage 

TealDataConnection$get_open_call(deparse = TRUE, args = NULL, silent = FALSE)

Arguments

deparse

(logical) whether return deparsed form of a call

args

(NULL or named list) additional arguments not set up previously

silent

(logical) whether convert all "missing function" errors to messages

Returns

optionally deparsed call object

Method get_open_error_message()

Get error message from last connection

Usage 

TealDataConnection$get_open_error_message()

Returns

(character)
text of the error message or character(0) if last connection was successful.

Method get_preopen_server()

Get shiny server module prior opening connection.

Usage 

TealDataConnection$get_preopen_server()

Returns

(function) shiny server prior opening connection.

Method get_open_server()

Get shiny server module to open connection.

Usage 

TealDataConnection$get_open_server()

Returns

(function) shiny server to open connection.

Method get_open_ui()

Get Shiny module with inputs to open connection

Usage 

TealDataConnection$get_open_ui(id)

Arguments

id

character shiny element id

Returns

(function) shiny UI to set arguments to open connection function.

Method is_open_failed()

Check if open connection has not failed.

Usage 

TealDataConnection$is_open_failed()

Returns

(logical) TRUE if open connection failed, else FALSE

Method set_open_args()

Set open connection function argument

Usage 

TealDataConnection$set_open_args(args, silent = FALSE)

Arguments

args

(NULL or named list) with values where list names are argument names

silent

(logical) whether convert all "missing function" errors to messages

Returns

(self) invisibly for chaining.

Method set_preopen_server()

Set pre-open connection server function

This function will be called before submit button will be hit.

Usage 

TealDataConnection$set_preopen_server(preopen_module)

Arguments

preopen_module

(function)
A shiny module server function

Returns

(self) invisibly for chaining.

Method set_open_server()

Set open connection server function

This function will be called after submit button will be hit. There is no possibility to specify some dynamic ui as server function is executed after hitting submit button.

Usage 

TealDataConnection$set_open_server(open_module)

Arguments

open_module

(function)
A shiny module server function that should load data from all connectors

Returns

(self) invisibly for chaining.

Method set_open_ui()

Set open connection UI function

Usage 

TealDataConnection$set_open_ui(open_module)

Arguments

open_module

(function)
shiny module as function. Inputs specified in this ui are passed to server module defined by set_open_server method.

Returns

(self) invisibly for chaining.

Method close()

Close the connection.

Usage 

TealDataConnection$close(silent = FALSE, try = FALSE)

Arguments

silent

(logical) whether convert all "missing function" errors to messages

try

(logical) whether perform function evaluation inside try clause

Returns

returns (self) if successful. For unsuccessful evaluation it depends on try argument: if try = TRUE then returns error, for try = FALSE otherwise

Method get_close_call()

Get executed close connection call

Usage 

TealDataConnection$get_close_call(deparse = TRUE, silent = FALSE)

Arguments

deparse

(logical) whether return deparsed form of a call

silent

(logical) whether convert all "missing function" errors to messages

Returns

optionally deparsed call object

Method get_close_error_message()

Get error message from last connection

Usage 

TealDataConnection$get_close_error_message()

Returns

(character)
text of the error message or character(0) if last connection was successful.

Method get_close_server()

Get shiny server module to close connection.

Usage 

TealDataConnection$get_close_server()

Returns

the server function to close connection.

Method is_close_failed()

Check if close connection has not failed.

Usage 

TealDataConnection$is_close_failed()

Returns

(logical) TRUE if close connection failed, else FALSE

Method set_close_args()

Set close connection function argument

Usage 

TealDataConnection$set_close_args(args, silent = FALSE)

Arguments

args

(named list) with values where list names are argument names

silent

(logical) whether convert all "missing function" errors to messages

Returns

(self) invisibly for chaining.

Method set_close_ui()

Set close connection UI function

Usage 

TealDataConnection$set_close_ui(close_module)

Arguments

close_module

(function)
shiny module as function. Inputs specified in this ui are passed to server module defined by set_close_server method.

Returns

(self) invisibly for chaining.

Method set_close_server()

Set close-connection server function

This function will be called after submit button will be hit. There is no possibility to specify some dynamic ui as server function is executed after hitting submit button.

Usage 

TealDataConnection$set_close_server(close_module)

Arguments

close_module

(function)
A shiny module server function that should load data from all connectors

Returns

(self) invisibly for chaining.

Method clone()

The objects of this class are cloneable with this method.

Usage 

TealDataConnection$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples 

open_fun <- callable_function(data.frame) # define opening function
open_fun$set_args(list(x = 1:5)) # define fixed arguments to opening function

close_fun <- callable_function(sum) # define closing function
close_fun$set_args(list(x = 1:5)) # define fixed arguments to closing function

ping_fun <- callable_function(function() TRUE)

x <- data_connection( # define connection
  ping_fun = ping_fun, # define ping function
  open_fun = open_fun, # define opening function
  close_fun = close_fun # define closing function
)

x$set_open_args(args = list(y = letters[1:5])) # define additional arguments if necessary

x$open() # call opening function
x$get_open_call() # check reproducible R code
#> [1] "data.frame(x = 1:5, y = c(\"a\", \"b\", \"c\", \"d\", \"e\"))"

# get data from connection via TealDataConnector$get_dataset()
if (FALSE) {
x$open(args = list(x = 1:5, y = letters[1:5])) # able to call opening function with arguments
x$close() # call closing function
}