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|
#' @importFrom R6 R6Class
NULL
Query <- R6::R6Class("Query",
private = list(
.vars = NULL
),
public = list(
con = NULL,
sql = NULL,
initialize = function(con, sql, vars) {
self$con <- con
self$sql <- sql
private$.vars <- vars
},
# nocov start
print = function(...) {
cat_line("<Query> ", self$sql)
print(self$con)
},
fetch = function(n = -1L) {
res <- dbSendQuery(self$con, self$sql)
on.exit(dbClearResult(res))
out <- dbFetch(res, n)
res_warn_incomplete(res)
out
},
# nocov end
fetch_paged = function(chunk_size = 1e4, callback) {
qry <- dbSendQuery(self$con, self$sql)
on.exit(dbClearResult(qry))
while (!dbHasCompleted(qry)) {
chunk <- dbFetch(qry, chunk_size)
callback(chunk)
}
invisible(TRUE)
},
# nocov start
vars = function() {
private$.vars
},
ncol = function() {
length(self$vars())
}
# nocov end
)
)
|
