~hrbrmstr/sergeant: fixed issue with 0-length query results

3 files changed, 85 insertions(+), 0 deletions(-)

M R/dbi.r
M R/query.r
M R/utils.r

M R/dbi.r => R/dbi.r +36 -0

@@ 235,6 235,42 @@ setMethod(
       if (length(out$columns) != 0) {
         if (is.data.frame(xdf)) {
           if (nrow(xdf) > 0) xdf <- xdf[,out$columns,drop=FALSE]
+        } else {
+          lapply(1:length(out$columns), function(col_idx) {
+            ctype <- out$metadata[col_idx]
+            if (ctype == "INT") {
+              integer(0)
+            } else if (ctype == "VARCHAR") {
+              character(0)
+            } else if (ctype == "TIMESTAMP") {
+              cx <- integer(0)
+              class(cx) <- "POSIXct"
+              cx
+            } else if (ctype == "BIGINT") {
+              integer64(0)
+            } else if (ctype == "BINARY") {
+              character(0)
+            } else if (ctype == "BOOLEAN") {
+              logical(0)
+            } else if (ctype == "DATE") {
+              cx <- integer(0)
+              class(cx) <- "Date"
+              cx
+            } else if (ctype == "FLOAT") {
+              numeric(0)
+            } else if (ctype == "DOUBLE") {
+              double(0)
+            } else if (ctype == "TIME") {
+              character(0)
+            } else if (ctype == "INTERVAL") {
+              character(0)
+            } else {
+              character(0)
+            }
+          }) -> xdf
+          xdf <- set_names(xdf, out$columns)
+          class(xdf) <- c("data.frame")
+          return(xdf)
         }
       }

M R/query.r => R/query.r +44 -0

@@ 95,6 95,50 @@ drill_uplift <- function(query_result) {
     query_result$rows <- query_result$rows[,query_result$columns,drop=FALSE]
   }
 
+  if (length(query_result$columns) != 0) {
+    if (is.data.frame(query_result$rows)) {
+      if (nrow(query_result$rows) > 0) query_result$rows <-
+          query_result$rows[,query_result$columns,drop=FALSE]
+    } else {
+      lapply(1:length(query_result$columns), function(col_idx) {
+        ctype <- query_result$metadata[col_idx]
+        if (ctype == "INT") {
+          integer(0)
+        } else if (ctype == "VARCHAR") {
+          character(0)
+        } else if (ctype == "TIMESTAMP") {
+          cx <- integer(0)
+          class(cx) <- "POSIXct"
+          cx
+        } else if (ctype == "BIGINT") {
+          integer64(0)
+        } else if (ctype == "BINARY") {
+          character(0)
+        } else if (ctype == "BOOLEAN") {
+          logical(0)
+        } else if (ctype == "DATE") {
+          cx <- integer(0)
+          class(cx) <- "Date"
+          cx
+        } else if (ctype == "FLOAT") {
+          numeric(0)
+        } else if (ctype == "DOUBLE") {
+          double(0)
+        } else if (ctype == "TIME") {
+          character(0)
+        } else if (ctype == "INTERVAL") {
+          character(0)
+        } else {
+          character(0)
+        }
+      }) -> xdf
+      xdf <- set_names(xdf, query_result$columns)
+      class(xdf) <- c("data.frame")
+      return(xdf)
+    }
+  }
+
+
   # ** only available in Drill 1.15.0+ **
   # be smarter about type conversion now that the REST API provides
   # the necessary metadata

M R/utils.r => R/utils.r +5 -0

@@ 27,3 27,8 @@ auth_drill <- function(ssl, host, port, username, password) {
   httr::stop_for_status(res)
 
 }
+
+set_names <- function(object = nm, nm) {
+  names(object) <- nm
+  object
+}