Add support for DBI::dbBind placeholder parameters

Author: kiwiroy

R/source_sql_to_dataframe.R

@@ -19,7 +19,7 @@ source_sql_to_dataframe <- function(path, params = NULL) {
         comment_close = sqltargets_option_get("sqltargets.jinja_comment_close"),
       )
     )
-  } else {
+  } else if (template_engine == "glue") {
     query <- glue::glue_data_sql(
       params,
       query,
@@ -28,7 +28,17 @@ source_sql_to_dataframe <- function(path, params = NULL) {
       .close = sqltargets_option_get("sqltargets.glue_sql_closing_delimiter")
     )
   }
-  out <- DBI::dbGetQuery(con, query)
+
+  if (template_engine %in% c("jinjar", "glue")) {
+    out <- DBI::dbGetQuery(con, query)
+  } else if (template_engine == "dbi") {
+    sth <- DBI::dbSendQuery(con, query)
+    DBI::dbBind(sth, params)
+    out <- DBI::dbFetch(sth, n = -1)
+    DBI::dbClearResult(sth)
+  } else {
+    stop(glue::glue("Unknown template engine: {template_engine}"))
+  }
   msg <- glue::glue("{basename(path)} executed:\n Rows: {nrow(out)}\n Columns: {ncol(out)}")
   cli::cli_alert_success(msg)
   return(out)

R/sqltargets-option.R

@@ -9,7 +9,7 @@
 #'
 #' Available Options
 #'
-#'  - `"sqltargets.template_engine"` - Either 'glue' or 'jinjar'. Determines how the query file should be parsed.
+#'  - `"sqltargets.template_engine"` - Either 'dbi', 'glue' or 'jinjar'. Determines how the query file should be parsed.
 #'
 #'  - `"sqltargets.glue_sql_opening_delimiter"` - character. Length 1. The opening delimiter passed to `glue::glue_sql()`.
 #'

README.Rmd

@@ -24,7 +24,7 @@ knitr::opts_chunk$set(
 
 <!-- badges: end -->
 
-sqltargets makes it easy to integrate SQL files within your [targets workflows.](https://github.com/ropensci/targets) The shorthand `tar_sql()` creates two targets: (1) the ‘upstream’ SQL file; and (2) the ‘downstream’ result of the query. Dependencies can be specified by calling `tar_load()` within SQL comments. The template engine can be specified using the `sqltargets.template_engine` option (either 'glue' or 'jinjar').
+sqltargets makes it easy to integrate SQL files within your [targets workflows.](https://github.com/ropensci/targets) The shorthand `tar_sql()` creates two targets: (1) the ‘upstream’ SQL file; and (2) the ‘downstream’ result of the query. Dependencies can be specified by calling `tar_load()` within SQL comments. The template engine can be specified using the `sqltargets.template_engine` option (either 'dbi', 'glue' or 'jinjar'). 'glue' is the default, 'dbi' is the simplest using [placeholders](https://dbi.r-dbi.org/reference/dbBind.html#details), and 'jinjar' is the most powerful.
 
 ## Installation
 
@@ -93,6 +93,30 @@ list(
   )
 ```
 
+With dbi:
+
+`query.sql`
+
+```sql
+-- !preview conn=DBI::dbConnect(RSQLite::SQLite())
+-- tar_load(params)
+select id
+from table
+where age > :age_threshold
+-- this could be $1, $age_threshold, or ? for SQLite
+```
+
+`_targets.R`
+
+```{r eval = FALSE}
+library(targets)
+library(sqltargets)
+list(
+  tar_target(params, list(age_threshold = 30)),
+  tar_sql(report, path = "query.sql", params = params)
+  )
+```
+
 With 'Jinja':
 
 `query.sql`

README.md

@@ -22,8 +22,10 @@ workflows.](https://github.com/ropensci/targets) The shorthand
 `tar_sql()` creates two targets: (1) the ‘upstream’ SQL file; and (2)
 the ‘downstream’ result of the query. Dependencies can be specified by
 calling `tar_load()` within SQL comments. The template engine can be
-specified using the `sqltargets.template_engine` option (either ‘glue’
-or ‘jinjar’).
+specified using the `sqltargets.template_engine` option (either ‘dbi’,
+‘glue’ or ‘jinjar’). ‘glue’ is the default, ‘dbi’ is the simplest using
+[placeholders](https://dbi.r-dbi.org/reference/dbBind.html#details), and
+‘jinjar’ is the most powerful.
 
 ## Installation
 
@@ -100,6 +102,30 @@ list(
   )
 ```
 
+With dbi:
+
+`query.sql`
+
+``` sql
+-- !preview conn=DBI::dbConnect(RSQLite::SQLite())
+-- tar_load(params)
+select id
+from table
+where age > :age_threshold
+-- this could be $1, $age_threshold, or ? for SQLite
+```
+
+`_targets.R`
+
+``` r
+library(targets)
+library(sqltargets)
+list(
+  tar_target(params, list(age_threshold = 30)),
+  tar_sql(report, path = "query.sql", params = params)
+  )
+```
+
 With ‘Jinja’:
 
 `query.sql`

tests/testthat/test-tar-sql.R

@@ -115,3 +115,113 @@ targets::tar_test("tar_sql() for Jinja for loop", {
                                credit_card_amount = 0,
                                gift_card_amount = 0))
 })
+
+targets::tar_test("tar_sql() with positional dbBind DBI engine", {
+  db_file <- tempfile(pattern = "sqlite", fileext = ".db")
+  lines <- c(
+    glue::glue("-- !preview conn=DBI::dbConnect(RSQLite::SQLite(), dbname = \"{db_file}\")"),
+    "-- tar_load(create_iris_table)",
+    "select distinct(species) as wide_petals from iris where [Petal.Width] > ?",
+    ""
+  )
+  writeLines(lines, "query.sql")
+  targets::tar_script({
+    library(sqltargets)
+    sqltargets_option_set("sqltargets.template_engine", "dbi")
+    list(
+      tar_target(test_db_file, db_file),
+      tar_target(create_iris_table, {
+        conn <- DBI::dbConnect(RSQLite::SQLite(), dbname = test_db_file)
+        on.exit(DBI::dbDisconnect(conn), after = TRUE)
+        DBI::dbWriteTable(conn, 'iris', iris)
+        TRUE
+      }),
+      tar_sql(
+        report,
+        path = "query.sql",
+        params = list(2.3)
+      )
+    )
+  })
+  suppressMessages(targets::tar_make(callr_function = NULL))
+  out <- targets::tar_read(report)
+  expect_equal(out, data.frame(wide_petals = "virginica"))
+})
+
+targets::tar_test("tar_sql() with named dbBind DBI engine", {
+  db_file <- tempfile(pattern = "sqlite", fileext = ".db")
+  lines <- c(
+    glue::glue("-- !preview conn=DBI::dbConnect(RSQLite::SQLite(), dbname = \"{db_file}\")"),
+    "-- tar_load(create_iris_table)",
+    "select distinct(species) as short_petals from iris where [Petal.Length] < $petal_length",
+    ""
+  )
+  writeLines(lines, "named_ph_dollar.sql")
+  lines <- c(
+    glue::glue("-- !preview conn=DBI::dbConnect(RSQLite::SQLite(), dbname = \"{db_file}\")"),
+    "-- tar_load(create_iris_table)",
+    "select distinct(species) as short_petals from iris where [Petal.Length] < :petal_length",
+    ""
+  )
+  writeLines(lines, "named_ph_colon.sql")
+  targets::tar_script({
+    library(sqltargets)
+    sqltargets_option_set("sqltargets.template_engine", "dbi")
+    list(
+      tar_target(test_db_file, db_file),
+      tar_target(create_iris_table, {
+        conn <- DBI::dbConnect(RSQLite::SQLite(), dbname = test_db_file)
+        on.exit(DBI::dbDisconnect(conn), after = TRUE)
+        DBI::dbWriteTable(conn, 'iris', iris)
+        TRUE
+      }),
+      tar_sql(
+        report,
+        path = "named_ph_dollar.sql",
+        params = list(petal_length=1.5)
+      ),
+      tar_sql(
+        report2,
+        path = "named_ph_colon.sql",
+        params = data.frame(petal_length=1.5)
+      )
+    )
+  })
+  suppressMessages(targets::tar_make(callr_function = NULL))
+  out <- targets::tar_read(report)
+  expect_equal(out, data.frame(short_petals = "setosa"))
+  out2 <- targets::tar_read(report2)
+  expect_equal(out2, data.frame(short_petals = "setosa"))
+})
+
+targets::tar_test("tar_sql() with indexed dbBind DBI engine", {
+  db_file <- tempfile(pattern = "sqlite", fileext = ".db")
+  lines <- c(
+    glue::glue("-- !preview conn=DBI::dbConnect(RSQLite::SQLite(), dbname = \"{db_file}\")"),
+    "-- tar_load(create_iris_table)",
+    "select species from iris where [Sepal.Length] > $1 and [Petal.Width] < $2 and [Sepal.Width] < $1",
+    ""
+  )
+  writeLines(lines, "query.sql")
+  targets::tar_script({
+    library(sqltargets)
+    sqltargets_option_set("sqltargets.template_engine", "dbi")
+    list(
+      tar_target(test_db_file, db_file),
+      tar_target(create_iris_table, {
+        conn <- DBI::dbConnect(RSQLite::SQLite(), dbname = test_db_file)
+        on.exit(DBI::dbDisconnect(conn), after = TRUE)
+        DBI::dbWriteTable(conn, 'iris', iris)
+        TRUE
+      }),
+      tar_sql(
+        report,
+        path = "query.sql",
+        params = list(5.0, 1.0)
+      )
+    )
+  })
+  suppressMessages(targets::tar_make(callr_function = NULL))
+  out <- targets::tar_read(report)
+  expect_equal(out, data.frame(Species = rep("setosa", 22)))
+})