Replace remote MySQL database with local SQLite database (#192)

DESCRIPTION

@@ -28,12 +28,11 @@ Suggests:
     dplyr,
     knitr,
     rmarkdown,
-    RMySQL,
     RSQLite,
     shiny,
     testthat (>= 3.0.0),
     tibble
-VignetteBuilder: 
+VignetteBuilder:
     knitr
 Config/Needs/website: tidyverse/tidytemplate
 Config/testthat/edition: 3

NAMESPACE

@@ -3,6 +3,7 @@
 export(Pool)
 export(dbBreak)
 export(dbPool)
+export(demoDb)
 export(localCheckout)
 export(onActivate)
 export(onDestroy)

NEWS.md

@@ -1,18 +1,20 @@
 # pool (development version)
 
+* Switched from hosted MySQL database to local SQLite database.
+
 # pool 1.0.3
 
-* Now explicitly requires DBI 1.2.0 (#178) and messages if you're using an 
+* Now explicitly requires DBI 1.2.0 (#178) and messages if you're using an
   old dbplyr (#179).
 
 # pool 1.0.2
 
 * No longer depends on the withr package, by instead requiring R 3.6.
 
-* Add wrappers for dbplyr generics `db_col_types()` (#171) and 
+* Add wrappers for dbplyr generics `db_col_types()` (#171) and
   `db_copy_to()` (#172).
 
-* Pool no longer generates spurious messages about needing to use 
+* Pool no longer generates spurious messages about needing to use
   `in_schema()` or avoiding the use of `ident_q()`.
 
 * Add support for new DBI generics that return Arrow objects.
@@ -21,7 +23,7 @@
 
 * `copy_to()` now returns a tbl that uses the Pool.
 
-* Added missing methods for `sql_join_suffix()` (#165) and 
+* Added missing methods for `sql_join_suffix()` (#165) and
   `sql_query_explain()` (#167).
 
 # pool 1.0.0
@@ -44,7 +46,7 @@
 * pool now implements the dbplyr 2.0.0 interface, eliminating warnings when
   using pool with dplyr (#132).
 
-* Pool errors and warnings have been reviewed with an eye to making them 
+* Pool errors and warnings have been reviewed with an eye to making them
   more immediately actionable (#145).
 
 * Objects are now validated once on first checkout to ensure that the
@@ -58,7 +60,7 @@
 
 * `dbPool()`'s `validateQuery` is now actually used (#153).
 
-* DBI methods should dispatch correctly in more cases; in particular 
+* DBI methods should dispatch correctly in more cases; in particular
   `dbReadTable()` and friends will now work correctly when used with
   `DBI::Id()` (#120).
 

R/DBI.R

@@ -32,29 +32,13 @@
 #' @export
 #' @examples
 #' # You use a dbPool in the same way as a standard DBI connection
-#' pool <- dbPool(RSQLite::SQLite())
+#' pool <- dbPool(RSQLite::SQLite(), dbname = demoDb())
 #' pool
 #'
-#' DBI::dbWriteTable(pool, "mtcars", mtcars)
 #' dbGetQuery(pool, "SELECT * FROM mtcars LIMIT 4")
 #'
 #' # Always close a pool when you're done using it
 #' poolClose(pool)
-#'
-#' # Using the RMySQL package
-#' if (requireNamespace("RMySQL", quietly = TRUE)) {
-#'   pool <- dbPool(
-#'     drv = RMySQL::MySQL(),
-#'     dbname = "shinydemo",
-#'     host = "shiny-demo.csa7qlmguqrf.us-east-1.rds.amazonaws.com",
-#'     username = "guest",
-#'     password = "guest"
-#'   )
-#'
-#'   dbGetQuery(pool, "SELECT * from City LIMIT 5;")
-#'
-#'   poolClose(pool)
-#' }
 dbPool <- function(drv,
                    ...,
                    minSize = 1,

R/utils.R

@@ -25,3 +25,27 @@ defer <- function(expr, envir = parent.frame(), after = FALSE) {
   thunk <- as.call(list(function() expr))
   do.call(on.exit, list(thunk, TRUE, after), envir = envir)
 }
+
+#' Create a demo SQLite database
+#'
+#' This function creates a temporary SQLite database for demonstration purposes.
+#' It populates the database with two tables: 'mtcars' and 'faithful'.
+#'
+#' @export
+#' @keywords internal
+demoDb <- function() {
+  check_installed("RSQLite")
+
+  path <- file.path(tools::R_user_dir("pool", "cache"), "demo.sqlite3")
+  dir.create(dirname(path), showWarnings = FALSE, recursive = TRUE)
+
+  if (!file.exists(path)) {
+    con <- DBI::dbConnect(RSQLite::SQLite(), path)
+    on.exit(DBI::dbDisconnect(con))
+
+    DBI::dbWriteTable(con, "mtcars", datasets::mtcars, row.names = "model")
+    DBI::dbWriteTable(con, "faithful", datasets::faithful)
+  }
+
+  path
+}

README.md

@@ -17,41 +17,35 @@ Learn more about why pool is needed in `vignette("why-pool")`.
 
 ## Usage
 
-Here’s a simple example of using a pool within a Shiny app (feel free to try it yourself):
+Here’s a simple example of using a pool within a Shiny app:
 
 ```r
 library(shiny)
 library(dplyr)
 library(pool)
 loadNamespace("dbplyr")
 
-pool <- dbPool(
-  drv = RMySQL::MySQL(),
-  dbname = "shinydemo",
-  host = "shiny-demo.csa7qlmguqrf.us-east-1.rds.amazonaws.com",
-  username = "guest",
-  password = "guest"
-)
+pool <- dbPool(RSQLite::SQLite(), dbname = demoDb())
 onStop(function() {
   poolClose(pool)
 })
 
 ui <- fluidPage(
-  textInput("ID", "Enter your ID:", "5"),
+  textInput("cyl", "Enter your number of cylinders:", "4"),
   tableOutput("tbl"),
-  numericInput("nrows", "How many cities to show?", 10),
+  numericInput("nrows", "How many cars to show?", 10),
   plotOutput("popPlot")
 )
 
 server <- function(input, output, session) {
-  city <- tbl(pool, "City")
+  cars <- tbl(pool, "mtcars")
 
   output$tbl <- renderTable({
-    city |> filter(ID == !!input$ID) |> collect()
+    cars %>% filter(cyl == !!input$cyl) %>% collect()
   })
   output$popPlot <- renderPlot({
-    df <- city |> head(input$nrows) |> collect()
-    pop <- df |> pull("Population", name = "Name")
+    df <- cars %>% head(input$nrows) %>% collect()
+    pop <- df %>% pull("mpg", name = "model")
     barplot(pop)
   })
 }

vignettes/.gitignore

@@ -1,2 +1,4 @@
 *.html
 *.R
+
+/.quarto/

vignettes/articles/advanced-pool.Rmd

@@ -1,7 +1,7 @@
 ---
 title: "Advanced usage"
 desc: >
-  This article discusses how to customize your pool and how to handle 
+  This article discusses how to customize your pool and how to handle
   transactions.
 ---
 
@@ -32,17 +32,11 @@ First, let's get to know our Pool object:
 ```{r}
 library(pool)
 
-pool <- dbPool(
-  drv = RMySQL::MySQL(),
-  dbname = "shinydemo",
-  host = "shiny-demo.csa7qlmguqrf.us-east-1.rds.amazonaws.com",
-  username = "guest",
-  password = "guest"
-)
+pool <- dbPool(RSQLite::SQLite(), dbname = demoDb())
 pool
 ```
 
-As you can see, printing gives you basic information about your pool. This can be useful to learn how many connections you have open (both free/idle and in use). 
+As you can see, printing gives you basic information about your pool. This can be useful to learn how many connections you have open (both free/idle and in use).
 
 But for this section, let's turn our attention to other parameters that you can pass to `dbPool()`: `minSize`, `maxSize`, and `idleTimeout`.
 
@@ -59,11 +53,8 @@ library(DBI)
 library(pool)
 
 pool <- dbPool(
-  drv = RMySQL::MySQL(),
-  dbname = "shinydemo",
-  host = "shiny-demo.csa7qlmguqrf.us-east-1.rds.amazonaws.com",
-  username = "guest",
-  password = "guest",
+  RSQLite::SQLite(),
+  dbname = demoDb(),
   minSize = 10,
   idleTimeout = 60 * 60
 )
@@ -73,7 +64,7 @@ poolClose(pool)
 
 ## Transactions
 
-So far, we've recommended you always use the pool object directly when you need to query the database. There's one challenge where this is not possible: transactions. Because for a transaction, you need to have access to the same connection for longer than a single query. The following will not necessary work because the pool might give you a different connection for each 
+So far, we've recommended you always use the pool object directly when you need to query the database. There's one challenge where this is not possible: transactions. Because for a transaction, you need to have access to the same connection for longer than a single query. The following will not necessary work because the pool might give you a different connection for each
 
 ```{r}
 #| eval: false