From b03c2691cd5f53cd729fb0f5412f6dc3d43e74af Mon Sep 17 00:00:00 2001
From: Craig Williams <craig@avsdev.uk>
Date: Tue, 27 Jan 2026 14:36:38 +0000
Subject: [PATCH] Class implementation for DBConnection and DBClient

---
 R/DBClient.R                      |  43 ++++++++
 R/DBClientClass/CRUDKeys.R        |  42 ++++++++
 R/DBClientClass/CRUDRow.R         |  28 ++++++
 R/DBClientClass/CRUDRows.R        | 158 ++++++++++++++++++++++++++++++
 R/DBClientClass/Initialize.R      |   8 ++
 R/DBClientClass/dbAction.R        |   6 ++
 R/DBClientClass/dbCollect.R       |  52 ++++++++++
 R/DBClientClass/dbQuery.R         |   9 ++
 R/DBClientClass/dbSchema.R        |  21 ++++
 R/DBClientClass/dbTable.R         |   7 ++
 R/DBClientClass/dbTransaction.R   |   8 ++
 R/DBConnection.R                  |  43 ++++++++
 R/DBConnectionClass/Configure.R   |  68 +++++++++++++
 R/DBConnectionClass/Connect.R     |  85 ++++++++++++++++
 R/DBConnectionClass/Transaction.R |  39 ++++++++
 R/PrintDebug.R                    |  97 ++++++++++++++++++
 16 files changed, 714 insertions(+)
 create mode 100644 R/DBClient.R
 create mode 100644 R/DBClientClass/CRUDKeys.R
 create mode 100644 R/DBClientClass/CRUDRow.R
 create mode 100644 R/DBClientClass/CRUDRows.R
 create mode 100644 R/DBClientClass/Initialize.R
 create mode 100644 R/DBClientClass/dbAction.R
 create mode 100644 R/DBClientClass/dbCollect.R
 create mode 100644 R/DBClientClass/dbQuery.R
 create mode 100644 R/DBClientClass/dbSchema.R
 create mode 100644 R/DBClientClass/dbTable.R
 create mode 100644 R/DBClientClass/dbTransaction.R
 create mode 100644 R/DBConnection.R
 create mode 100644 R/DBConnectionClass/Configure.R
 create mode 100644 R/DBConnectionClass/Connect.R
 create mode 100644 R/DBConnectionClass/Transaction.R
 create mode 100644 R/PrintDebug.R

diff --git a/R/DBClient.R b/R/DBClient.R
new file mode 100644
index 0000000..a717c75
--- /dev/null
+++ b/R/DBClient.R
@@ -0,0 +1,43 @@
+
+class_env <- new.env(parent = baseenv())
+
+res <- lapply(list.files("R/DBClientClass", pattern = ".R"), function(fn) {
+  eval(
+    parse(paste0("R/DBClientClass/", fn)),
+    envir = class_env,
+    enclos = emptyenv()
+  )
+})
+
+fn_names <- names(which(vapply(class_env, is.function, logical(1))))
+fn_list <- lapply(fn_names, function(fn_name) {
+  class_env[[fn_name]]
+})
+names(fn_list) <- fn_names
+
+priv_fn_names <- ls(class_env, pattern = "^\\..*", all.names = TRUE)
+priv_fn_list <- lapply(priv_fn_names, function(fn_name) {
+  class_env[[fn_name]]
+})
+names(priv_fn_list) <- gsub("^\\.", "", priv_fn_names)
+
+member_names <- names(which(!vapply(class_env, is.function, logical(1))))
+member_list <- lapply(member_names, function(member_name) {
+  class_env[[member_name]]
+})
+names(member_list) <- member_names
+
+
+#' @name DBClient
+#' @title DBClient
+#' @description Database client class
+NULL
+
+#' @export
+DBClient <- R6::R6Class(
+  "DBClient",
+  public = fn_list,
+  private = c(member_list, priv_fn_list),
+  lock_class = TRUE,
+  parent_env = class_env
+)
diff --git a/R/DBClientClass/CRUDKeys.R b/R/DBClientClass/CRUDKeys.R
new file mode 100644
index 0000000..b7a9fa3
--- /dev/null
+++ b/R/DBClientClass/CRUDKeys.R
@@ -0,0 +1,42 @@
+keyExists <- function(table_name, key_name, id) {
+  key <- dbplyr::ident(key_name)
+  res <- self$table(table_name) %>%
+    dplyr::filter(key == !!id) %>%
+    dplyr::count() %>%
+    dplyr::pull(n)
+  return(res[[1]] > 0)
+}
+
+selectByKey <- function(table_name, key_name, id) {
+  key <- dbplyr::ident(key_name)
+  res <- self$table(table_name) %>%
+    dplyr::filter(key %in% !!id) %>%
+    dplyr::collect()
+  return(res)
+}
+
+insertByKey <- function(table_name, key_name, id, ...) {
+  row <- dplyr::bind_cols(
+    tibble::tibble(!!key_name := !!id), tibble::as_tibble(list(...))
+  )
+  self$insertRows(table_name, row, key_name)
+}
+
+updateByKey <- function(table_name, key_name, id, ...) {
+  row <- dplyr::bind_cols(
+    tibble::tibble(!!key_name := !!id), tibble::as_tibble(list(...))
+  )
+  self$updateRows(table_name, row, key_name)
+}
+
+upsertByKey <- function(table_name, key_name, id, ...) {
+  row <- dplyr::bind_cols(
+    tibble::tibble(!!key_name := !!id), tibble::as_tibble(list(...))
+  )
+  self$upsertRows(table_name, row, key_name)
+}
+
+deleteByKey <- function(table_name, key_name, id) {
+  row <- tibble::tibble_row(!!key_name := !!id)
+  self$deleteRows(table_name, row, key_name)
+}
diff --git a/R/DBClientClass/CRUDRow.R b/R/DBClientClass/CRUDRow.R
new file mode 100644
index 0000000..d10a823
--- /dev/null
+++ b/R/DBClientClass/CRUDRow.R
@@ -0,0 +1,28 @@
+insert <- function(table_name, ..., key_name = NULL) {
+  row <- tibble::as_tibble(list(...))
+  self$insertRows(table_name, row, key_name)
+}
+
+append <- function(table_name, ...) {
+  row <- tibble::as_tibble(list(...))
+  self$appendRows(table_name, row)
+}
+
+upsert <- function(table_name, ..., key_name = NULL) {
+  row <- tibble::as_tibble(list(...))
+  self$upsertRows(table_name, row, key_name)
+}
+
+update <- function(table_name, ..., key_name = NULL) {
+  row <- tibble::as_tibble(list(...))
+  self$updateRows(table_name, row, key_name)
+}
+
+delete <- function(table_name, ..., key_name = NULL) {
+  row <- tibble::as_tibble(list(...))
+  self$deleteRows(table_name, row, key_name)
+}
+
+truncate <- function(table_name) {
+  self$dbAction(paste("TRUNCATE TABLE", self$withSchema(table_name)))
+}
diff --git a/R/DBClientClass/CRUDRows.R b/R/DBClientClass/CRUDRows.R
new file mode 100644
index 0000000..96e8173
--- /dev/null
+++ b/R/DBClientClass/CRUDRows.R
@@ -0,0 +1,158 @@
+
+
+# NOTE: Temporary fix for issue: tidyverse/dbplyr#1133
+.fix_dbplyr <- function(tbl) {
+  keys <- c("dbplyr_table_ident", "dbplyr_table_path")
+
+  if (sum(keys %in% class(tbl$lazy_query$x)) == 0) {
+    tbl$lazy_query$x <- dbplyr::as.sql(
+      tbl$lazy_query$x, private$client$getConnection()
+    )
+  }
+
+  return(tbl)
+}
+
+
+insertRows <- function(table_name, rows, key_name = NULL) {
+  tbl <- self$table(table_name)
+  new_rows <- dbplyr::copy_inline(private$client$getConnection(), rows)
+
+  if (getOption("db.simulate", FALSE)) {
+    return(printDebug("insertRows", table_name, key_name, tbl, rows, TRUE))
+  }
+  if (getOption("db.debug", FALSE)) {
+    printDebug("insertRows", table_name, key_name, tbl, rows)
+  }
+
+  tbl <- private$fix_dbplyr(tbl)
+
+  tbl <- dplyr::rows_insert(
+    tbl,
+    new_rows,
+    by = key_name,
+    conflict = "ignore",
+    in_place = TRUE,
+    returning = !!key_name
+  )
+
+  if (dbplyr::has_returned_rows(tbl)) {
+    return(dbplyr::get_returned_rows(tbl))
+  }
+
+  return(invisible(tbl))
+}
+
+appendRows <- function(table_name, rows, key_name = NULL) {
+  tbl <- self$table(table_name)
+  new_rows <- dbplyr::copy_inline(private$client$getConnection(), rows)
+
+  if (getOption("db.simulate", FALSE)) {
+    return(printDebug("appendRows", table_name, key_name, tbl, rows, TRUE))
+  }
+  if (getOption("db.debug", FALSE)) {
+    printDebug("appendRows", table_name, key_name, tbl, rows)
+  }
+
+  tbl <- private$fix_dbplyr(tbl)
+
+  tbl <- dplyr::rows_append(
+    tbl, new_rows, in_place = TRUE, returning = !!key_name
+  )
+
+  if (dbplyr::has_returned_rows(tbl)) {
+    return(dbplyr::get_returned_rows(tbl))
+  }
+
+  return(invisible(TRUE))
+}
+
+upsertRows <- function(table_name, rows, key_name = NULL) {
+  tbl <- self$table(table_name)
+  new_rows <- dbplyr::copy_inline(private$client$getConnection(), rows)
+
+  tbl <- private$fix_dbplyr(tbl)
+
+  # NOTE: Temporary fix for issue: tidyverse/dbplyr#1279
+  if ("MariaDBConnection" %in% class(private$client$getConnection())) {
+    keys <- rows %>%
+      dplyr::pull(!!key_name)
+    n_rows <- tbl %>%
+      dplyr::select(!!key_name) %>%
+      dplyr::filter(!!as.symbol(key_name) %in% !!keys) %>%
+      dplyr::count() %>%
+      dplyr::pull(n)
+    if (n_rows == 0) {
+      return(insertRows(table_name, rows, key_name))
+    } else {
+      return(updateRows(table_name, rows, key_name))
+    }
+  } else {
+    if (getOption("db.simulate", FALSE)) {
+      return(printDebug("upsertRows", table_name, key_name, tbl, rows, TRUE))
+    }
+    if (getOption("db.debug", FALSE)) {
+      printDebug("upsertRows", table_name, key_name, tbl, rows)
+    }
+
+    tbl <- dplyr::rows_upsert(tbl, new_rows, by = key_name, in_place = TRUE)
+    if (dbplyr::has_returned_rows(tbl)) {
+      return(dbplyr::get_returned_rows(tbl))
+    }
+  }
+
+  return(invisible(TRUE))
+}
+
+updateRows <- function(table_name, rows, key_name = NULL) {
+  tbl <- self$table(table_name)
+  new_rows <- dbplyr::copy_inline(private$client$getConnection(), rows)
+
+  if (getOption("db.simulate", FALSE)) {
+    return(printDebug("updateRows", table_name, key_name, tbl, rows, TRUE))
+  }
+  if (getOption("db.debug", FALSE)) {
+    printDebug("updateRows", table_name, key_name, tbl, rows)
+  }
+
+  tbl <- private$fix_dbplyr(tbl)
+
+  tbl <- dplyr::rows_update(
+    tbl, new_rows, by = key_name, unmatched = "ignore", in_place = TRUE
+  )
+
+  if (dbplyr::has_returned_rows(tbl)) {
+    return(dbplyr::get_returned_rows(tbl))
+  }
+
+  return(invisible(TRUE))
+}
+
+deleteRows <- function(table_name, rows, key_name = NULL) {
+  tbl <- self$table(table_name)
+  old_rows <- dbplyr::copy_inline(private$client$getConnection(), rows)
+
+  if (getOption("db.simulate", FALSE)) {
+    return(printDebug("deleteRows", table_name, key_name, tbl, rows, TRUE))
+  }
+  if (getOption("db.debug", FALSE)) {
+    printDebug("deleteRows", table_name, key_name, tbl, rows)
+  }
+
+  tbl <- private$fix_dbplyr(tbl)
+
+  tbl <- dplyr::rows_delete(
+    tbl,
+    old_rows,
+    by = key_name,
+    unmatched = "ignore",
+    in_place = TRUE,
+    returning = dplyr::everything()
+  )
+
+  if (dbplyr::has_returned_rows(tbl)) {
+    return(dbplyr::get_returned_rows(tbl))
+  }
+
+  return(invisible(TRUE))
+}
diff --git a/R/DBClientClass/Initialize.R b/R/DBClientClass/Initialize.R
new file mode 100644
index 0000000..1e54499
--- /dev/null
+++ b/R/DBClientClass/Initialize.R
@@ -0,0 +1,8 @@
+client <- NULL
+
+Initialize <- function(client) {
+  if (is.null(client) || !is.R6(client) || inherits(client, "DBClient")) {
+  	stop("DBClient instance required!")
+  }
+  private$client <- client
+}
diff --git a/R/DBClientClass/dbAction.R b/R/DBClientClass/dbAction.R
new file mode 100644
index 0000000..5673afb
--- /dev/null
+++ b/R/DBClientClass/dbAction.R
@@ -0,0 +1,6 @@
+dbAction <- function(statement) {
+  if (getOption("db.debug", FALSE)) {
+    cat("dbQuery:", statement, "\n")
+  }
+  DBI::dbExecute(private$client$getConnection(), statement)
+}
diff --git a/R/DBClientClass/dbCollect.R b/R/DBClientClass/dbCollect.R
new file mode 100644
index 0000000..07b6edf
--- /dev/null
+++ b/R/DBClientClass/dbCollect.R
@@ -0,0 +1,52 @@
+collectOrReturn <- function(
+  qry, collect = get("collect", pos = parent.frame())
+) {
+  if (length(collect) == 1 && collect[[1]] == TRUE) {
+    return(dplyr::collect(qry))
+  } else {
+    return(qry)
+  }
+}
+
+collectGeometries <- function(
+  qry, geometry_cols = c("geometry"), geometry_crs = 4326, check_ring_dir = TRUE
+) {
+  requireNamespace("sf")
+
+  qry <- qry %>%
+    dplyr::collect()
+
+  if (sum(geometry_cols %in% colnames(qry)) > 0) {
+    qry <- qry %>%
+      dplyr::mutate(
+        dplyr::across(dplyr::any_of(geometry_cols), function(.col) {
+          sf::st_as_sfc(
+            .col,
+            EWKB = TRUE,
+            crs = geometry_crs,
+            check_ring_dir = check_ring_dir
+          )
+        })
+      )
+  }
+
+  if ("geom" %in% colnames(qry) && sum("geom" %in% geometry_cols) == 0) {
+    qry <- qry %>%
+      dplyr::mutate(
+        geom = sf::st_as_sfc(
+          geom, EWKB = TRUE, crs = 4326, check_ring_dir = check_ring_dir
+        )
+      )
+  }
+
+  if ("proj" %in% colnames(qry) && sum("proj" %in% geometry_cols) == 0) {
+    qry <- qry %>%
+      dplyr::mutate(
+        proj = sf::st_as_sfc(
+          proj, EWKB = TRUE, crs = 3035, check_ring_dir = check_ring_dir
+        )
+      )
+  }
+
+  return(qry)
+}
diff --git a/R/DBClientClass/dbQuery.R b/R/DBClientClass/dbQuery.R
new file mode 100644
index 0000000..24a3be7
--- /dev/null
+++ b/R/DBClientClass/dbQuery.R
@@ -0,0 +1,9 @@
+dbQuery <- function(statement) {
+  if (getOption("db.debug", FALSE)) {
+    cat("dbQuery:", statement, "\n")
+  }
+  query <- DBI::dbSendQuery(private$client$getConnection(), statement)
+  res <- DBI::dbFetch(query)
+  DBI::dbClearResult(query)
+  res
+}
diff --git a/R/DBClientClass/dbSchema.R b/R/DBClientClass/dbSchema.R
new file mode 100644
index 0000000..7572774
--- /dev/null
+++ b/R/DBClientClass/dbSchema.R
@@ -0,0 +1,21 @@
+withSchema <- function(table_name) {
+  config <- private$client$getConfiguration()
+  if (exists("schema", config)) {
+    return(DBI::dbQuoteIdentifier(
+      getConnection(), DBI::Id(schema = config$schema, table = table_name)
+    ))
+  } else {
+    return(DBI::dbQuoteIdentifier(
+      getConnection(), DBI::Id(table = table_name)
+    ))
+  }
+}
+
+dplyrWithSchema <- function(table_name) {
+  config <- private$client$getConfiguration()
+  if (exists("schema", config) && !is.null(config$schema)) {
+    return(dbplyr::in_schema(config$schema, table_name))
+  } else {
+    return(table_name)
+  }
+}
diff --git a/R/DBClientClass/dbTable.R b/R/DBClientClass/dbTable.R
new file mode 100644
index 0000000..e33e54a
--- /dev/null
+++ b/R/DBClientClass/dbTable.R
@@ -0,0 +1,7 @@
+
+table <- function(table_name) {
+  if (getOption("db.debug", FALSE)) {
+    cat("dbTable:", table_name, "\n")
+  }
+  dplyr::tbl(private$client$getConnection(), self$dplyrWithSchema(table_name))
+}
diff --git a/R/DBClientClass/dbTransaction.R b/R/DBClientClass/dbTransaction.R
new file mode 100644
index 0000000..9786cca
--- /dev/null
+++ b/R/DBClientClass/dbTransaction.R
@@ -0,0 +1,8 @@
+
+withTransaction <- function(expr) {
+  private$client$beginTransaction()
+  on.exit(private$client$rollbackTransaction())
+  expr
+  on.exit()
+  private$client$commitTransaction()
+}
diff --git a/R/DBConnection.R b/R/DBConnection.R
new file mode 100644
index 0000000..1985258
--- /dev/null
+++ b/R/DBConnection.R
@@ -0,0 +1,43 @@
+
+class_env <- new.env(parent = baseenv())
+
+res <- lapply(list.files("R/DBConnectionClass", pattern = ".R"), function(fn) {
+  eval(
+    parse(paste0("R/DBConnectionClass/", fn)),
+    envir = class_env,
+    enclos = emptyenv()
+  )
+})
+
+fn_names <- names(which(vapply(class_env, is.function, logical(1))))
+fn_list <- lapply(fn_names, function(fn_name) {
+  class_env[[fn_name]]
+})
+names(fn_list) <- fn_names
+
+priv_fn_names <- ls(class_env, pattern = "^\\..*", all.names = TRUE)
+priv_fn_list <- lapply(priv_fn_names, function(fn_name) {
+  class_env[[fn_name]]
+})
+names(priv_fn_list) <- gsub("^\\.", "", priv_fn_names)
+
+member_names <- names(which(!vapply(class_env, is.function, logical(1))))
+member_list <- lapply(member_names, function(member_name) {
+  class_env[[member_name]]
+})
+names(member_list) <- member_names
+
+
+#' @name DBConnection
+#' @title DBConnection
+#' @description Database Connection class
+NULL
+
+#' @export
+DBConnection <- R6::R6Class(
+  "DBConnection",
+  public = fn_list,
+  private = c(member_list, priv_fn_list),
+  lock_class = TRUE,
+  parent_env = class_env
+)
diff --git a/R/DBConnectionClass/Configure.R b/R/DBConnectionClass/Configure.R
new file mode 100644
index 0000000..1df0141
--- /dev/null
+++ b/R/DBConnectionClass/Configure.R
@@ -0,0 +1,68 @@
+config <- NULL
+
+.configureList <- function(db) {
+  was_connected <- FALSE
+  if (!is.null(private$conn)) {
+    was_connected <- TRUE
+    disconnect()
+  }
+
+  private$config <- db
+
+  if (was_connected) {
+    connect()
+  }
+
+  return(invisible(private$config))
+}
+
+.configureDefault <- function(
+  host, port, user, password, dbname,
+  engine = NULL, name = NULL, schema = NULL, autoconnect = NULL
+) {
+  if (is.null(autoconnect)) {
+    autoconnect <- getOption("db.autoconnect", FALSE)
+  }
+  private$configureList(list(
+    engine = engine,
+    host = host,
+    port = port,
+    user = user,
+    password = password,
+    name = ifelse(is.null(name), dbname, name),
+    schema = schema,
+    autoconnect = autoconnect
+  ))
+}
+
+
+#' Configures the DBClient instance.
+#'
+#' There are 2 options for configuration, either: pass in a named list; or use
+#' named parameters. The required elements are:
+#'
+#' @param ... Named parameters for configuring the connection or a name list of
+#'    parameters
+#' @param engine The database engine (mysql, postgres) as supported by DBI
+#' @param host The database host
+#' @param port The database port
+#' @param user The database user to connect with
+#' @param password The database password to connect with
+#' @param dbname The database to use
+#' @param schema The database schema to use (postgres)
+#' @param autoconnect Autoconnect to the database if not already connected
+#'
+#' @return The configuration accepted
+configure <- function(...) {
+  args <- list(...)
+  if (sum("list" %in% class(args[[1]])) > 0) {
+    private$configureList(args[[1]])
+  } else {
+    do.call(private$configureDefault, args)
+  }
+}
+
+#' Get the current configuration of the DBClient instance.
+getConfiguration <- function() {
+  private$config
+}
diff --git a/R/DBConnectionClass/Connect.R b/R/DBConnectionClass/Connect.R
new file mode 100644
index 0000000..644bd9e
--- /dev/null
+++ b/R/DBConnectionClass/Connect.R
@@ -0,0 +1,85 @@
+conn <- NULL
+
+connect <- function() {
+  if (is.null(private$config)) {
+    if (!file.exists("global.R")) {
+      return(FALSE)
+    }
+    warning("Attempting to load default configuration from global.R")
+    e <- new.env(parent = baseenv())
+    eval(parse("global.R"), envir = e)
+    if ("db" %in% ls(e)) {
+      self$configure(e$db)
+    } else if ("global" %in% ls(e)) {
+      self$configure(e$global$db)
+    } else {
+      return(FALSE)
+    }
+  }
+
+  engine_fn <- NULL
+  if (exists("engine", private$config) && length(private$config$engine) > 0) {
+    engine_fn <- switch(
+      private$config$engine,
+      mariadb = RMariaDB::MariaDB,
+      postgres = RPostgres::Postgres
+    )
+  }
+  if (is.null(engine_fn)) {
+    if (exists("schema", private$config)) {
+      engine_fn <- RPostgres::Postgres
+    } else {
+      engine_fn <- RMariaDB::MariaDB
+    }
+  }
+
+  private$conn <- DBI::dbConnect(
+    engine_fn(),
+    host = private$config$host,
+    port = private$config$port,
+    dbname = private$config$name,
+    user = private$config$user,
+    password = private$config$password
+  )
+
+  res <- tryCatch(
+    {
+      DBI::dbListTables(private$conn)
+      TRUE
+    },
+    error = function(err) {
+      print("Database error:")
+      utils::str(err)
+      return(FALSE)
+    }
+  )
+
+  return(res)
+}
+
+getConnection <- function(do_connect = NULL) {
+  if (!self$isConnected()) {
+    if ((!is.null(do_connect) && do_connect)
+      || (is.null(do_connect) && private$conn$autoconnect)) {
+      connect()
+    } else {
+      warning("Database is not connected. Caller of getConnection() may error.")
+    }
+  }
+  return(private$conn)
+}
+
+isConnected <- function() {
+  return(!is.null(private$conn))
+}
+
+disconnect <- function() {
+  if (!is.null(private$conn)) {
+    DBI::dbDisconnect(private$conn)
+    private$conn <- NULL
+  }
+}
+
+disconnectOnSessionEnd <- function(session) {
+  session$onSessionEnded(self$disconnect)
+}
diff --git a/R/DBConnectionClass/Transaction.R b/R/DBConnectionClass/Transaction.R
new file mode 100644
index 0000000..af6a1de
--- /dev/null
+++ b/R/DBConnectionClass/Transaction.R
@@ -0,0 +1,39 @@
+
+transactionLevel <- 0
+
+beginTransaction <- function(allowRecursive = FALSE, quietly = FALSE) {
+  if (private$transactionLevel > 0) {
+  	if (allowRecursive == FALSE) {
+  	  if (quietly != FALSE) {
+  	  	stop("Transaction already started. Aborting.")
+  	  }
+  	  return(FALSE)
+  	}
+  }
+  private$transactionLevel <- private$transactionLevel + 1
+  DBI::dbBegin(self$getConnection())
+}
+
+rollbackTransaction <- function(quietly = FALSE) {
+  if (private$transactionLevel == 0) {
+    if (quietly != FALSE) {
+      stop("No transaction to rollback. Aborting.")
+    }
+    return(FALSE)
+  }
+  DB::dbRollback(self$getConnection())
+}
+
+commitTransaction <- function(quietly = FALSE) {
+  if (private$transactionLevel == 0) {
+    if (quietly != FALSE) {
+      stop("No transaction to commit. Aborting.")
+    }
+    return(FALSE)
+  }
+  private$transactionLevel <- private$transactionLevel - 1
+  if (transactionLevel > 0) {
+  	return(TRUE)
+  }
+  DB::dbRollback(self$getConnection())
+}
diff --git a/R/PrintDebug.R b/R/PrintDebug.R
new file mode 100644
index 0000000..4d4b32e
--- /dev/null
+++ b/R/PrintDebug.R
@@ -0,0 +1,97 @@
+
+printDebugSQLInsert <- function(con, table, cols, from, key) {
+  dbplyr::sql_query_insert(
+    con = con,
+    table = table,
+    from = from,
+    insert_cols = cols,
+    by = key,
+    conflict = "ignore"
+  )
+}
+printDebugSQLAppend <- function(con, table, cols, from, key) {
+  dbplyr::sql_query_append(
+    con = con,
+    table = table,
+    from = from,
+    insert_cols = cols
+  )
+}
+printDebugSQLUpsert <- function(con, table, cols, from, key) {
+  dbplyr::sql_query_upsert(
+    con = con,
+    table = table,
+    from = from,
+    by = key,
+    update_cols = setdiff(cols, key)
+  )
+}
+printDebugSQLUpdate <- function(con, table, cols, from, key) {
+  update_cols <- setdiff(cols, key)
+  update_values <- dbplyr:::sql_table_prefix(con, update_cols, "...y")
+  names(update_values) <- update_cols
+  dbplyr::sql_query_update_from(
+    con = con,
+    table = table,
+    from = from,
+    by = key,
+    update_values = update_values
+  )
+}
+printDebugSQLDelete <- function(con, table, cols, from, key) {
+  dbplyr::sql_query_delete(
+    con = con,
+    table = table,
+    from = from,
+    by = key
+  )
+}
+printDebug <- function(fn_name, table, key, tbl, rows, query_only = FALSE) {
+  if (!query_only) {
+    cat(fn_name, ": ", table, " (", key, ")\n", sep = "")
+    cat("\t")
+    dplyr::glimpse(tbl)
+    cat("\t")
+    dplyr::glimpse(rows)
+  }
+
+  sqlFn <- switch(
+    tolower(substr(fn_name, 1, 3)),
+    `ins` = printDebugSQLInsert,
+    `app` = printDebugSQLAppend,
+    `ups` = printDebugSQLUpsert,
+    `upd` = printDebugSQLUpdate,
+    `del` = printDebugSQLDelete
+  )
+  con <- dbplyr::remote_con(tbl)
+  lvl <- ifelse(startsWith(fn_name, "del"), 2, 1)
+  sql <- sqlFn(
+    con,
+    dbplyr:::target_table(tbl, TRUE),
+    colnames(rows),
+    dbplyr::sql_render(dbplyr::copy_inline(con, rows), con, lvl = lvl),
+    key
+  )
+  cat(sql, "\n")
+
+  if (is.null(key)) {
+    return(invisible(rows))
+  }
+
+  return_keys <- NULL
+  if (key %in% colnames(rows)) {
+    return_keys <- rows %>%
+      dplyr::select(key)
+  } else {
+    return_keys <- rows %>%
+      dplyr::bind_rows(tibble::tibble(!!key := character(0))) %>%
+      dplyr::mutate(
+        !!key := dplyr::coalesce(
+          !!!dplyr::sym(key),
+          paste0("<<NEW_ID::", round(stats::runif(1, 1, 100000)), ">>")
+        )
+      ) %>%
+      dplyr::select(key)
+  }
+  return(invisible(return_keys))
+}