From 4f7b4d7ee0c08a57c57c233374d114def143eff3 Mon Sep 17 00:00:00 2001
From: Maximilian Girlich <maximilian.girlich@metoda.com>
Date: Fri, 2 Sep 2022 08:01:54 +0000
Subject: [PATCH] Use default schema in `dm_learn_from_db()`

---
 R/db-helpers.R | 44 +++++++++++++++++++++++++++++++++-----------
 R/learn.R      |  1 +
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/R/db-helpers.R b/R/db-helpers.R
index 5e8998d27..ba7a6e897 100644
--- a/R/db-helpers.R
+++ b/R/db-helpers.R
@@ -115,33 +115,25 @@ repair_table_names_for_db <- function(table_names, temporary, con, schema = NULL
 }
 
 get_src_tbl_names <- function(src, schema = NULL, dbname = NULL) {
+  schema <- check_schema(src, schema)
+
   if (!is_mssql(src) && !is_postgres(src) && !is_mariadb(src)) {
-    warn_if_arg_not(schema, only_on = c("MSSQL", "Postgres", "MariaDB"))
     warn_if_arg_not(dbname, only_on = "MSSQL")
     return(set_names(src_tbls(src)))
   }
-
   con <- con_from_src_or_con(src)
 
-  if (!is.null(schema)) {
-    check_param_class(schema, "character")
-    check_param_length(schema)
-  }
-
   if (is_mssql(src)) {
     # MSSQL
-    schema <- schema_mssql(con, schema)
     dbname_sql <- dbname_mssql(con, dbname)
     names_table <- get_names_table_mssql(con, dbname_sql)
     dbname <- names(dbname_sql)
   } else if (is_postgres(src)) {
     # Postgres
-    schema <- schema_postgres(con, schema)
     dbname <- warn_if_arg_not(dbname, only_on = "MSSQL")
     names_table <- get_names_table_postgres(con)
   } else if (is_mariadb(src)) {
     # MariaDB
-    schema <- schema_mariadb(con, schema)
     dbname <- warn_if_arg_not(dbname, only_on = "MSSQL")
     names_table <- get_names_table_mariadb(con)
   }
@@ -155,6 +147,31 @@ get_src_tbl_names <- function(src, schema = NULL, dbname = NULL) {
     deframe()
 }
 
+check_schema <- function(src, schema) {
+  if (!is_mssql(src) && !is_postgres(src) && !is_mariadb(src)) {
+    warn_if_arg_not(schema, only_on = c("MSSQL", "Postgres", "MariaDB"))
+    return(schema)
+  }
+
+  con <- con_from_src_or_con(src)
+
+  if (!is.null(schema)) {
+    check_param_class(schema, "character")
+    check_param_length(schema)
+  }
+
+  if (is_mssql(src)) {
+    # MSSQL
+    schema_mssql(con, schema)
+  } else if (is_postgres(src)) {
+    # Postgres
+    schema_postgres(con, schema)
+  } else if (is_mariadb(src)) {
+    # MariaDB
+    schema_mariadb(con, schema)
+  }
+}
+
 # `schema_*()` : default schema if NULL, otherwise unchanged
 schema_mssql <- function(con, schema) {
   if (is_null(schema)) {
@@ -170,9 +187,14 @@ schema_postgres <- function(con, schema) {
   schema
 }
 
+ident_q <- function(...) {
+  # to avoid dependency on dbplyr define `ident_q()` here (not exported from dplyr)
+  structure(c(...), class = c("ident_q", "ident", "character"))
+}
+
 schema_mariadb <- function(con, schema) {
   if (is_null(schema)) {
-    schema <- sql("database()")
+    schema <- ident_q("database()")
   }
   schema
 }
diff --git a/R/learn.R b/R/learn.R
index e0f91baf5..abce87d4e 100644
--- a/R/learn.R
+++ b/R/learn.R
@@ -41,6 +41,7 @@ dm_learn_from_db <- function(dest, dbname = NA, schema = NULL, name_format = "{t
     return()
   }
 
+  schema <- check_schema(src, schema)
   info <- dm_meta(con, catalog = dbname, schema = schema)
 
   df_info <-