change the code extracting data.frame name form query in duckdb.r

R/duckdf.R

@@ -2,72 +2,46 @@ duckdf <- function(query = "",
                    persist = FALSE,
                    df_name = NULL,
                    db_name = NULL) {
-
-# If they want a DuckDB on disk.....
-if (persist == TRUE) {
-
+  
+  # If they want a DuckDB on disk.....
+  if (persist == TRUE) {
+    
     duckdf::persist(query,
                     db_name)
-
-} else {
-
-# create a DuckDB connection, either as a temporary in-memory database (default)
-con <- DBI::dbConnect(duckdb::duckdb(), dbdir = ":memory:", read_only = FALSE)
-
-# if there's a named dataframe (or multiple), do this
-if (!is.null(df_name)) {
-
-duckdb_reg <- function(x) {  
-
-  duckdb::duckdb_register(con, paste(x), get(x))}
-
-  sapply(df_name, duckdb_reg)
-
-} else {
-
-# if there isn't a named dataframe, string queries
-# Extract dataframe name using string splits
-query_split <- stringi::stri_split_fixed(query, "FROM",
-                                         omit_empty = TRUE,
-                                         opts_fixed = stringi::stri_opts_fixed(case_insensitive = TRUE))
-
-query_split <- trimws(unlist(query_split))
-
-from_df_first <- stringi::stri_extract_first_words(query_split[2], 
-                                                   locale = NULL)
-
-# register a dataframe view in duckdb
-duckdb::duckdb_register(con, paste(from_df_first), get(from_df_first))
-
-# If a JOIN exists do this
-if (stringi::stri_detect_fixed(query, "JOIN",
-                  opts_fixed = stringi::stri_opts_fixed(case_insensitive = TRUE)) == TRUE) {
-
-# Extract dataframe name using sting splits
-query_split_second <- stringi::stri_split_fixed(query, "JOIN",
-                                                omit_empty = TRUE,
-                                                opts_fixed = stringi::stri_opts_fixed(case_insensitive = TRUE))
-
-query_split_second <- trimws(unlist(query_split_second))
-
-from_df_second <- stringi::stri_extract_first_words(query_split_second[2],
-                                                    locale = NULL)
-
-# register a dataframe view in duckdb
-duckdb::duckdb_register(con, paste(from_df_second), get(from_df_second))
-
-            }
+
+  } else {
+
+    # create a DuckDB connection, either as a temporary in-memory database (default)
+    con <- DBI::dbConnect(duckdb::duckdb(), dbdir = ":memory:", read_only = FALSE)
+
+    # if there's NOT a named dataframe (or multiple), find them in the query
+    if (is.null(df_name)) {
+      query_dfs=stringr::str_match_all(query, '(?i)(\\bfrom\\b|\\bjoin\\b)\\s*(\\w+)')[[1]][,3]
+      query_dfs=unique(query_dfs)
+      if_df_exists=function(x){
+        tryCatch(
+          expr = {  is(eval.parent(parse(text=x)), "data.frame")  },
+          error = function(e){  F  } )
         }
-
-# execute required SQL query against the new DuckDB table
-statement_result <- DBI::dbGetQuery(con, query)
-
-# close the connection
-DBI::dbDisconnect(con, shutdown = TRUE)
-
-# return results
-return(statement_result)
-
+      if(length(query_dfs)>0) df_name= query_dfs[ sapply(query_dfs,if_df_exists) ]
     }
+
+      duckdb_reg <- function(x) {  
+
+        duckdb::duckdb_register(con, paste(x), get(x))}
+
+      if (!is.null(df_name)) sapply(df_name, duckdb_reg)
+
+
+
+    # execute required SQL query against the new DuckDB table
+    statement_result <- DBI::dbGetQuery(con, query)
+
+    # close the connection
+    DBI::dbDisconnect(con, shutdown = TRUE)
+
+    # return results
+    return(statement_result)
+
+  }
 }
-