F# SQLProvider Columns Order Doesn't match the order in the table - postgresql

Question

I select from a postgresql view\table and export the values into excel file.
The excel file column order need to be the same as the table, but the sqlProvider select them with abc order...
My Code is:
module ViewToExcel
open System
open System.IO
//open Microsoft.Office.Interop.Excel
open System.Drawing
open Npgsql
open FSharp.Data.Sql
open OfficeOpenXml
open Casaubon
open NpgsqlTypes
let [<Literal>] connectionString = #"Server=localhost;Database=db;User Id=postgres;Password=;"
let [<Literal>] npgPath = #"..\packages\Npgsql.3.1.7\lib\net451"
type sqlConnection = SqlDataProvider<ConnectionString = connectionString,
DatabaseVendor = Common.DatabaseProviderTypes.POSTGRESQL,
ResolutionPath = npgPath,
IndividualsAmount = 1000,
UseOptionTypes = true>
let functionParseViewToExcel (excelPath:string, serverName:string, dbName:string) =
/////////////////////////////////Get Data Connection///////////////////////
printf "connect to db\n"
let connectionUserString = #"Server="+serverName+";Database="+dbName+";User Id=postgres;Password=;"
let ctx = sqlConnection.GetDataContext(connectionUserString)
let weekCalcView = ctx.Public.CcVibeWeeklyCalculations
// weekCalcView|> Seq.toList
let weekCalcViewSeq = ctx.Public.CcVibeWeeklyCalculations|> Seq.toArray
////////////////////////////////// Start Excel//////////////////////////////
let newExcelFile = FileInfo(excelPath + "cc_vibe_treatment_period_"+ DateTime.Today.ToString("yyyy_dd_MM")+".xlsx");
if (newExcelFile.Exists) then
newExcelFile.Delete();
let pck = new ExcelPackage(newExcelFile);
//Add the 'xxx' sheet
let ws = pck.Workbook.Worksheets.Add("xxx");
//printf "success to start the excel file\n"
let mutable columNames = "blabla"
for col in weekCalcViewSeq.[0].ColumnValues do
let columnName = match col with |(a, _) -> a
//printf "a %A\n" columnName
let columnNamewithPsic = "," + columnName
columNames <- columNames + columnNamewithPsic
ws.Cells.[1, 1].LoadFromText(columNames.Replace("blabla,",""))|> ignore
ws.Row(1).Style.Fill.PatternType <- Style.ExcelFillStyle.Solid
ws.Row(1).Style.Fill.BackgroundColor.SetColor(Color.FromArgb(170, 170, 170))
ws.Row(1).Style.Font.Bold <- true;
ws.Row(1).Style.Font.UnderLine <- true;
let mutable subject = weekCalcViewSeq.[0].StudySubjectLabel.Value // in order to color the rows according to subjects
let mutable color = 0
for row in 1.. weekCalcViewSeq.Length do
let mutable columValues = "blabla"
for col in weekCalcViewSeq.[row-1].ColumnValues do
let columnValue = match col with |(_, a) -> a
//printf "a %A\n" columnValue
match columnValue with
| null -> columValues <- columValues + "," + ""
| _ -> columValues <- columValues + "," + columnValue.ToString()
ws.Cells.[row + 1, 1].LoadFromText(columValues.Replace("blabla,",""))|> ignore
/////////////////////Color the row according to subject///////////////
if (weekCalcViewSeq.[row - 1].StudySubjectLabel.Value = subject) then
if (color = 0) then
ws.Row(row + 1).Style.Fill.PatternType <- Style.ExcelFillStyle.Solid
ws.Row(row + 1).Style.Fill.BackgroundColor.SetColor(Color.FromArgb(255,255,204))
else
ws.Row(row + 1).Style.Fill.PatternType <- Style.ExcelFillStyle.Solid
ws.Row(row + 1).Style.Fill.BackgroundColor.SetColor(Color.White)
else
subject <- weekCalcViewSeq.[row - 1].StudySubjectLabel.Value
if (color = 0) then
color <- 1
ws.Row(row + 1).Style.Fill.PatternType <- Style.ExcelFillStyle.Solid
ws.Row(row + 1).Style.Fill.BackgroundColor.SetColor(Color.White)
else
color <- 0
ws.Row(row + 1).Style.Fill.PatternType <- Style.ExcelFillStyle.Solid
ws.Row(row + 1).Style.Fill.BackgroundColor.SetColor(Color.FromArgb(255,255,204))
pck.Save()
The Excel Output fields is:
bloating_avg,caps_fail,caps_success,date_of_baseline_visit,discomfort_avg and etc...
But the order in the table isn't the same.
Could someone help me?
Thanks!

Answer 1

You can write a small helper function to extract the field (column) names via npgqsl. After that you can just use this list of column names to create your excel table. The getColNames function gets it from a DataReader. Obviously you can refactor it further, to get at the tablename as parameter, etc.
#r #"..\packages\SQLProvider.1.0.33\lib\FSharp.Data.SqlProvider.dll"
#r #"..\packages\Npgsql.3.1.7\lib\net451\Npgsql.dll"
open System
open FSharp.Data.Sql
open Npgsql
open NpgsqlTypes
let conn = new NpgsqlConnection("Host=localhost;Username=postgres;Password=root;Database=postgres;Pooling=false")
conn.Open()
let cmd = new NpgsqlCommand()
cmd.Connection <- conn
cmd.CommandText <- """ SELECT * FROM public."TestTable1" """
let recs = cmd.ExecuteReader()
let getColNames (recs:NpgsqlDataReader) =
let columns = recs.GetColumnSchema() |> Seq.toList
columns |> List.map (fun x -> x.BaseColumnName)
let colnames = getColNames recs
//val colnames : string list = ["ID"; "DT"; "ADAY"]
rec.Dispose()
conn.Dispose()
You can see that the column names are not in alphabetical order. You could use this column name list to get at the records in the correct order. Or just use the Reader object directly without the type provider.
Edit: Using records to map the table
It is also possible to extract the data, using the type provider, in the required format, by wiring up the types, and then using .MapTo<T>:
type DataRec = {
DT:DateTime
ADAY:String
ID:System.Int64
}
type sql = SqlDataProvider<dbVendor,connString2,"",resPath,indivAmount,useOptTypes>
let ctx = sql.GetDataContext()
let table1 = ctx.Public.TestTable1
let qry = query { for row in table1 do
select row} |> Seq.map (fun x -> x.MapTo<DataRec>())
qry |> Seq.toList
val it : DataRec list = [{DT = 2016/09/27 00:00:00;
ADAY = "Tuesday";
ID = 8L;}; {DT = 2016/09/26 00:00:00;
ADAY = "Monday";
ID = 9L;}; {DT = 2016/09/25 00:00:00;
ADAY = "Sunday";