Merge pull request #1127 from cynkra/f-learn-mysql-2-tweaks

 use helper to centralize info about schema-supported databases

R/db-helpers.R

@@ -68,6 +68,21 @@ is_mariadb <- function(dest) {
   inherits_any(dest, c("MariaDBConnection", "src_MariaDBConnection", "src_DoltConnection", "src_DoltLocalConnection"))
 }
 
+schema_supported_dbs <- function() {
+  tibble::tribble(
+    ~db_name, ~id_function, ~test_shortcut,
+    "SQL Server", "is_mssql", "mssql",
+    "Postgres", "is_postgres", "postgres",
+    "MariaDB", "is_mariadb", "maria",
+  )
+}
+
+is_schema_supported <- function(con) {
+  funs <- schema_supported_dbs()[["id_function"]]
+
+  any(purrr::map_lgl(funs, ~ do.call(., args = list(dest = con))))
+}
+
 src_from_src_or_con <- function(dest) {
   if (is.src(dest)) dest else dbplyr::src_dbi(dest)
 }
@@ -90,7 +105,7 @@ repair_table_names_for_db <- function(table_names, temporary, con, schema = NULL
     names <- unique_db_table_name(names)
   } else {
     # permanent tables
-    if (!is.null(schema) && !is_mssql(con) && !is_postgres(con) && !is_mariadb(con)) {
+    if (!is.null(schema) && !is_schema_supported(con)) {
       abort_no_schemas_supported(con = con)
     }
     names <- table_names

tests/testthat/helper-skip.R

@@ -23,6 +23,15 @@ skip_if_src_not <- function(...) {
   }
 }
 
+skip_if_schema_supported <- function() {
+  not_ok_dbs <- schema_supported_dbs()[["test_shortcut"]]
+  skip_if_src(not_ok_dbs)
+}
+skip_if_schema_not_supported <- function() {
+  not_ok_dbs <- schema_supported_dbs()[["test_shortcut"]]
+  skip_if_src_not(not_ok_dbs)
+}
+
 skip_if_ide <- function() {
   if (!isTRUE(as.logical(Sys.getenv("CI")))) {
     skip("Slow test. To run, set CI=true")

tests/testthat/test-db-interface.R

@@ -182,8 +182,8 @@ test_that("copy_dm_to() works with schema argument for MSSQL & Postgres", {
   )
 })
 
-test_that("copy_dm_to() fails with schema argument for databases other than MSSQL & Postgres", {
-  skip_if_src("mssql", "postgres", "maria")
+test_that("copy_dm_to() fails with schema argument for databases where schema is unsupported", {
+  skip_if_schema_supported()
 
   local_dm <- dm_for_filter() %>% collect()
 

tests/testthat/test-learn.R

@@ -1,7 +1,7 @@
 # FIXME: #313: learn only from current source
 
 test_that("Standard learning from MSSQL (schema 'dbo') or Postgres (schema 'public') and get_src_tbl_names() works?", {
-  skip_if_src_not(c("mssql", "postgres", "maria"))
+  skip_if_schema_not_supported()
 
   # dm_learn_from_mssql() --------------------------------------------------
   con_db <- my_test_con()
@@ -42,7 +42,7 @@ test_that("Standard learning from MSSQL (schema 'dbo') or Postgres (schema 'publ
 })
 
 test_that("Standard learning from MSSQL (schema 'dbo') or Postgres (schema 'public') and get_src_tbl_names() works?", {
-  skip_if_src_not(c("mssql", "postgres", "maria"))
+  skip_if_schema_not_supported()
 
   # dm_learn_from_mssql() --------------------------------------------------
   con_db <- my_test_con()
@@ -109,7 +109,7 @@ test_that("Standard learning from MSSQL (schema 'dbo') or Postgres (schema 'publ
 
 
 test_that("Learning from specific schema on MSSQL or Postgres works?", {
-  skip_if_src_not(c("mssql", "postgres", "maria"))
+  skip_if_schema_not_supported()
 
   # produces a randomized schema name with a length of 4-10 characters
   # consisting of the symbols in `reservoir`
@@ -406,7 +406,7 @@ test_that("Learning from a specific schema in another DB for MSSQL works?", {
 # Must be in the same file as the other learning tests
 # to avoid race conditions.
 test_that("dm_meta() contents", {
-  skip_if_src_not(c("mssql", "postgres", "maria"))
+  skip_if_schema_not_supported()
 
   # produces a randomized schema name with a length of 4-10 characters
   # consisting of the symbols in `reservoir`

tests/testthat/test-meta.R

@@ -6,7 +6,7 @@ test_that("dummy", {
 })
 
 test_that("dm_meta() data model", {
-  skip_if_src_not(c("mssql", "postgres", "maria"))
+  skip_if_schema_not_supported()
 
   expect_snapshot({
     dm_meta(my_test_src()) %>%

vignettes/dm.Rmd

@@ -55,6 +55,7 @@ fin_dm
 ``````
 
 The dm object interrogates the RDBMS for table and column information, and primary and foreign keys.
+Currently, primary and foreign keys are only available from `r glue::glue_collapse(dm:::schema_supported_dbs()[["db_name"]], sep = ", ", last = " and ")`.
 
 
 ## Selecting tables
@@ -77,7 +78,6 @@ fin_dm_small <-
   dm_select_tbl(loans, accounts, districts, trans)
 ```
 
-
 ## Linking tables by adding keys
 
 In many cases, `dm_from_con()` already returns a dm with all keys set.
@@ -92,7 +92,7 @@ fin_dm_small <-
   dm_select_tbl(loans, accounts, districts, trans)
 ``````
 
-In our data model, `id` columns uniquely identify records in the `accounts` and `loans` tables, and can be used as a primary key.
+In our data model, `id` columns uniquely identify records in the `accounts` and `loans` tables, and was used as a primary key.
 A primary key is defined with `dm_add_pk()`.
 Each loan is linked to one account via the `account_id` column in the `loans` table, the relationship is established with `dm_add_fk()`.