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#' spec_meta_column_info
#' @family meta specifications
#' @usage NULL
#' @format NULL
#' @keywords NULL
spec_meta_column_info <- list(
column_info_formals = function() {
# <establish formals of described functions>
expect_equal(names(formals(dbColumnInfo)), c("res", "..."))
},
column_info = function(ctx, con, table_name) {
#' @return
#' `dbColumnInfo()`
penguins <- get_penguins(ctx)
dbWriteTable(con, table_name, penguins)
res <- local_result(dbSendQuery(con, paste0("SELECT * FROM ", table_name)))
fields <- dbColumnInfo(res)
#' returns a data frame
expect_s3_class(fields, "data.frame")
#' with at least two columns `"name"` and `"type"` (in that order)
expect_equal(names(fields)[1:2], c("name", "type"))
#' (and optional columns that start with a dot).
expect_true(all(grepl("^[.]", names(fields)[-1:-2])))
#' The `"name"` and `"type"` columns contain the names and types
#' of the R columns of the data frame that is returned from [`dbFetch()`].
penguins_ret <- dbFetch(res)
expect_identical(fields$name, names(penguins_ret))
#' The `"type"` column is of type `character` and only for information.
expect_type(fields$type, "character")
#' Do not compute on the `"type"` column, instead use `dbFetch(res, n = 0)`
#' to create a zero-row data frame initialized with the correct data types.
},
#'
column_info_closed = function(con) {
#' @section Failure modes:
#' An attempt to query columns for a closed result set raises an error.
query <- trivial_query()
res <- dbSendQuery(con, query)
dbClearResult(res)
expect_error(dbColumnInfo(res))
},
column_info_row_names = function(con, table_name) {
#' @section Specification:
#'
#' A column named `row_names` is treated like any other column.
dbWriteTable(con, table_name, data.frame(a = 1L, row_names = 2L))
res <- local_result(dbSendQuery(con, paste0("SELECT * FROM ", table_name)))
expect_identical(dbColumnInfo(res)$name, c("a", "row_names"))
},
#'
column_info_consistent = function(ctx, con) {
res <- local_result(dbSendQuery(con, "SELECT 1.5 AS a, 2.5 AS b"))
#' The column names are always consistent
info <- dbColumnInfo(res)
#' with the data returned by `dbFetch()`.
data <- dbFetch(res)
expect_identical(info$name, names(data))
},
#'
column_info_consistent_unnamed = function(ctx, con) {
# odbc package
skip_if_not_dbitest(ctx, "1.7.2")
#' If the query returns unnamed columns,
res <- local_result(dbSendQuery(con, "SELECT 1.5, 2.5 AS a, 1.5, 3.5"))
info <- dbColumnInfo(res)
data <- dbFetch(res)
expect_identical(info$name, names(data))
expect_equal(data[["a"]], 2.5)
#' non-empty and non-`NA` names are assigned.
expect_false(anyNA(names(data)))
expect_true(all(names(data) != ""))
},
#'
column_info_consistent_keywords = function(ctx, con) {
#' Column names that correspond to SQL or R keywords are left unchanged.
res <- local_result(dbSendQuery(con, paste0("SELECT 1.5 AS ", dbQuoteIdentifier(con, "for"))))
info <- dbColumnInfo(res)
data <- dbFetch(res)
expect_identical(info$name, names(data))
expect_equal(data[["for"]], 1.5)
},
#
NULL
)
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