Add list_doc() to list meta document references by type

NAMESPACE

@@ -10,4 +10,5 @@ export(drop_database_tables)
 export(get_doc)
 export(get_download_ranges)
 export(insert_location_info)
+export(list_doc)
 export(remove_doc)

NEWS.md

@@ -1,3 +1,2 @@
 # ATdatabase 0.0.1
 
-* Start of development

R/list_doc.R

@@ -0,0 +1,36 @@
+#' Lists all references for a meta-document type
+#'
+#' This function lists the references (ref) of all meta-data documents
+#' in the database for a given type.
+#'
+#' @param type character string with type
+#' @param conn database connection object
+#'
+#' @return character vector of references (ref) for the given type, or
+#'   NA if no documents of that type exist
+#'
+#' A meta-data document is an R object which is stored in the database.
+#' Each object has a type and reference (ref) so they are findable.
+#' This function returns all references belonging to a certain type.
+#'
+#' @export
+#'
+
+
+list_doc <- function(type, conn) {
+
+    if (!is.character(type)) {
+        stop("ERROR list_doc: type is not character")
+    }
+
+    qry <- glue::glue_sql("SELECT ref FROM meta WHERE type={type};",
+                          .con = conn)
+
+    res <- pool::dbGetQuery(conn, qry)
+    if (length(res$ref) == 0) {
+        ref <- NA
+    } else {
+        ref <- res$ref
+    }
+    return(ref)
+}

tests/testthat/test-list_doc.R

@@ -0,0 +1,30 @@
+test_that("list_doc input", {
+
+    create_database_tables(dbconn)
+    expect_error(list_doc(type = 1, conn = dbconn))
+    drop_database_tables(dbconn)
+
+})
+
+
+
+test_that("list_doc output", {
+
+    create_database_tables(dbconn)
+    x <- data.frame(x = rnorm(5), y = rnorm(5))
+
+    add_doc(type = "test", ref = "a", doc = x, conn = dbconn)
+    add_doc(type = "test", ref = "b", doc = x, conn = dbconn)
+    add_doc(type = "other", ref = "c", doc = x, conn = dbconn)
+
+    refs <- list_doc(type = "test", conn = dbconn)
+    expect_equal(sort(refs), c("a", "b"))
+
+    refs2 <- list_doc(type = "other", conn = dbconn)
+    expect_equal(refs2, "c")
+
+    refs3 <- list_doc(type = "nonexistent", conn = dbconn)
+    expect_true(is.na(refs3))
+
+    drop_database_tables(dbconn)
+})