Improved error handling.

R/getGeneralWQPData.R

@@ -31,6 +31,44 @@ getGeneralWQPData <- function(...){
                    urlCall,
                    "&mimeType=tsv",sep = "")
   
-  suppressWarnings(retval <- read.delim(urlCall, header = TRUE, quote="\"", dec=".", sep='\t', colClasses=c('character'), fill = TRUE))
-  return(retval)
+  doc = tryCatch({
+    h <- basicHeaderGatherer()
+    doc <- getURL(urlCall, headerfunction = h$update)
+    
+  }, warning = function(w) {
+    message(paste("URL caused a warning:", urlCall))
+    message(w)
+  }, error = function(e) {
+    message(paste("URL does not seem to exist:", urlCall))
+    message(e)
+    return(NA)
+  })
+  
+  if(h$value()["Content-Type"] == "text/tab-separated-values;charset=UTF-8"){
+    
+    numToBeReturned <- as.numeric(h$value()["Total-Result-Count"])
+    
+    if (!is.na(numToBeReturned) | numToBeReturned != 0){
+      retval <- read.delim(textConnection(doc), header = TRUE, quote="\"", 
+                           dec=".", sep='\t', 
+                           colClasses=c('character'), 
+                           fill = TRUE)
+      
+      actualNumReturned <- nrow(retval)
+      
+      if(actualNumReturned != numToBeReturned) warning(numToBeReturned, " sample results were expected, ", actualNumReturned, " were returned")
+      
+      return(retval)
+    } else {
+      warning(paste("No data to retrieve from",urlCall))
+      return(NA)
+    }
+    
+  } else {
+    message(paste("URL caused an error:", urlCall))
+    message("Content-Type=",h$value()["Content-Type"])
+    return(NA)
+  }
+
+  
 }
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