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#' spec_result_get_query
#' @family result specifications
#' @usage NULL
#' @format NULL
#' @keywords NULL
spec_result_get_query <- list(
get_query_formals = function() {
# <establish formals of described functions>
expect_equal(names(formals(dbGetQuery)), c("conn", "statement", "..."))
},
get_query_atomic = function(con) {
#' @return
#' `dbGetQuery()` always returns a [data.frame], with
#' as many rows as records were fetched and as many
#' columns as fields in the result set,
#' even if the result is a single value
query <- trivial_query()
rows <- check_df(dbGetQuery(con, query))
expect_equal(rows, data.frame(a = 1.5))
},
get_query_one_row = function(con) {
#' or has one
query <- trivial_query(3, letters[1:3])
result <- trivial_df(3, letters[1:3])
rows <- check_df(dbGetQuery(con, query))
expect_identical(rows, result)
},
get_query_zero_rows = function(con) {
#' or zero rows.
# Not all SQL dialects seem to support the query used here.
query <-
"SELECT * FROM (SELECT 1 as a, 2 as b, 3 as c) AS x WHERE (1 = 0)"
rows <- check_df(dbGetQuery(con, query))
expect_identical(names(rows), letters[1:3])
expect_identical(dim(rows), c(0L, 3L))
},
#'
get_query_closed_connection = function(ctx, closed_con) {
#' @section Failure modes:
#' An error is raised when issuing a query over a closed
expect_error(dbGetQuery(closed_con, trivial_query()))
},
get_query_invalid_connection = function(ctx, invalid_con) {
#' or invalid connection,
expect_error(dbGetQuery(invalid_con, trivial_query()))
},
get_query_syntax_error = function(con) {
#' if the syntax of the query is invalid,
expect_error(dbGetQuery(con, "SELLECT"))
},
get_query_non_string = function(con) {
#' or if the query is not a non-`NA` string.
expect_error(dbGetQuery(con, character()))
expect_error(dbGetQuery(con, letters))
expect_error(dbGetQuery(con, NA_character_))
},
get_query_n_bad = function(con) {
#' If the `n` argument is not an atomic whole number
#' greater or equal to -1 or Inf, an error is raised,
query <- trivial_query()
expect_error(dbGetQuery(con, query, n = -2))
expect_error(dbGetQuery(con, query, n = 1.5))
expect_error(dbGetQuery(con, query, n = integer()))
expect_error(dbGetQuery(con, query, n = 1:3))
},
get_query_good_after_bad_n = function(con) {
#' but a subsequent call to `dbGetQuery()` with proper `n` argument succeeds.
query <- trivial_query()
expect_error(dbGetQuery(con, query, n = -2))
rows <- check_df(dbGetQuery(con, query))
expect_equal(rows, data.frame(a = 1.5))
},
#' @section Additional arguments:
#' The following arguments are not part of the `dbGetQuery()` generic
#' (to improve compatibility across backends)
#' but are part of the DBI specification:
#' - `n` (default: -1)
#' - `params` (default: `NULL`)
#' - `immediate` (default: `NULL`)
#'
#' They must be provided as named arguments.
#' See the "Specification" and "Value" sections for details on their usage.
get_query_row_names = function(con) {
#' @section Specification:
#'
#' A column named `row_names` is treated like any other column.
query <- trivial_query(column = "row_names")
result <- trivial_df(column = "row_names")
rows <- check_df(dbGetQuery(con, query))
expect_identical(rows, result)
expect_identical(.row_names_info(rows), -1L)
},
#'
get_query_multi_row_single_column = function(ctx, con) {
#' The `n` argument specifies the number of rows to be fetched.
#' If omitted, fetching multi-row queries with one
query <- trivial_query(3, .ctx = ctx, .order_by = "a")
result <- trivial_df(3)
rows <- check_df(dbGetQuery(con, query))
expect_identical(rows, result)
},
get_query_multi_row_multi_column = function(ctx, con) {
#' or more columns returns the entire result.
query <- sql_union(
.ctx = ctx, paste("SELECT", 1:5 + 0.5, "AS a,", 4:0 + 0.5, "AS b"), .order_by = "a"
)
rows <- check_df(dbGetQuery(con, query))
expect_identical(rows, data.frame(a = 1:5 + 0.5, b = 4:0 + 0.5))
},
get_query_n_multi_row_inf = function(ctx, con) {
#' A value of [Inf] for the `n` argument is supported
#' and also returns the full result.
query <- trivial_query(3, .ctx = ctx, .order_by = "a")
result <- trivial_df(3)
rows <- check_df(dbGetQuery(con, query, n = Inf))
expect_identical(rows, result)
},
get_query_n_more_rows = function(ctx, con) {
#' If more rows than available are fetched (by passing a too large value for
#' `n`), the result is returned in full without warning.
query <- trivial_query(3, .ctx = ctx, .order_by = "a")
result <- trivial_df(3)
rows <- check_df(dbGetQuery(con, query, n = 5L))
expect_identical(rows, result)
},
get_query_n_zero_rows = function(ctx, con) {
#' If zero rows are requested, the columns of the data frame are still fully
#' typed.
query <- trivial_query(3, .ctx = ctx, .order_by = "a")
result <- trivial_df(0)
rows <- check_df(dbGetQuery(con, query, n = 0L))
expect_identical(rows, result)
},
get_query_n_incomplete = function(ctx, con) {
#' Fetching fewer rows than available is permitted,
#' no warning is issued.
query <- trivial_query(3, .ctx = ctx, .order_by = "a")
result <- trivial_df(2)
rows <- check_df(dbGetQuery(con, query, n = 2L))
expect_identical(rows, result)
},
#'
get_query_params = function(ctx, con) {
#' The `param` argument allows passing query parameters, see [dbBind()] for details.
placeholder_funs <- get_placeholder_funs(ctx)
for (placeholder_fun in placeholder_funs) {
placeholder <- placeholder_fun(1)
query <- paste0("SELECT ", placeholder, " + 1.0 AS a")
values <- trivial_values(3) - 1
params <- stats::setNames(list(values), names(placeholder))
ret <- dbGetQuery(con, query, params = params)
expect_equal(ret, trivial_df(3), info = placeholder)
}
},
get_query_immediate = function(con, table_name) {
#' @section Specification for the `immediate` argument:
#'
#' The `immediate` argument supports distinguishing between "direct"
#' and "prepared" APIs offered by many database drivers.
#' Passing `immediate = TRUE` leads to immediate execution of the
#' query or statement, via the "direct" API (if supported by the driver).
#' The default `NULL` means that the backend should choose whatever API
#' makes the most sense for the database, and (if relevant) tries the
#' other API if the first attempt fails. A successful second attempt
#' should result in a message that suggests passing the correct
#' `immediate` argument.
#' Examples for possible behaviors:
#' 1. DBI backend defaults to `immediate = TRUE` internally
#' 1. A query without parameters is passed: query is executed
#' 1. A query with parameters is passed:
#' 1. `params` not given: rejected immediately by the database
#' because of a syntax error in the query, the backend tries
#' `immediate = FALSE` (and gives a message)
#' 1. `params` given: query is executed using `immediate = FALSE`
#' 1. DBI backend defaults to `immediate = FALSE` internally
#' 1. A query without parameters is passed:
#' 1. simple query: query is executed
#' 1. "special" query (such as setting a config options): fails,
#' the backend tries `immediate = TRUE` (and gives a message)
#' 1. A query with parameters is passed:
#' 1. `params` not given: waiting for parameters via [dbBind()]
#' 1. `params` given: query is executed
res <- expect_visible(dbGetQuery(con, trivial_query(), immediate = TRUE))
check_df(res)
},
#
NULL
)
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