I am trying to embed results from a Sql Query into an html table using GO as the back end. To iterate row results in Go, the Rows.Next() function is used. This works for printing to the console window, but not for a html table. Here is my Go Code:
package main
// Database connection Code for http://play.golang.org/p/njPBsg0JjD
import (
"net/http"
"html/template"
"fmt"
"github.com/LukeMauldin/lodbc"
"github.com/jmoiron/sqlx"
"database/sql"
)
//declare database class
var db *sqlx.DB
type webdata struct {
Title string
Heading string
GridTitle string
ColumnHeading [9]string
RowData [9]string
NumOfRows *sql.Rows
}
//this is the function handler to handle '/mbconsole'
func ConsoleHandler(w http.ResponseWriter, r *http.Request) {
//declare an instance of webdata
var wdata webdata
//connect to database
//Set ODBC driver level
lodbc.SetODBCVersion(lodbc.ODBCVersion_3)
var err error
//connect to a Microsoft SQL Server
db, err = sqlx.Open("lodbc", "[connectionstring]")
if err == nil {
fmt.Println("Connection successful")
}else{
fmt.Println("SQL Connection error", err)
}
// Execute the queries
rows, err := db.Query("[Select ...]")
if err != nil {
panic(err.Error())
}
// Get column names
columns, err := rows.Columns()
if err != nil {
panic(err.Error())
}
// Make a slice for the values
values := make([]interface{}, len(columns))
// rows.Scan wants '[]interface{}' as an argument, so we must copy the
// references into such a slice
// See http://code.google.com/p/go-wiki/wiki/InterfaceSlice for details
scanArgs := make([]interface{}, len(values))
for i := range values {
scanArgs[i] = &values[i]
}
//fill table headings, the table returns 9 columns so I just hard coded it
for i:=0;i<9;i++ {
wdata.ColumnHeading[i] = columns[i]
}
wdata.NumOfRows = rows
// Fetch rows
for rows.Next() {
err = rows.Scan(scanArgs...)
if err != nil {
panic(err.Error())
}
// Print data
for i, value := range values {
switch value.(type) {
case nil:
wdata.RowData[i] = "NULL"
case []byte:
wdata.RowData[i] = string(value.([]byte))
default:
wdata.RowData[i] = fmt.Sprint(value)
}
}
}
wdata.Title = "Page Title"
wdata.Heading = "My View"
wdata.GridTitle = "My Grid Title"
//get the template the data will be loaded into
t1, err := template.ParseFiles("template.html")
if t1 == nil {
fmt.Println("File Not Found: ", err)
}
//load the template with data and display
terr := t1.Execute(w, &wdata)
if terr != nil {
fmt.Println("terr: ", terr)
}
db = db.Unsafe()
defer db.Close()
}
func main() {
http.HandleFunc("/",ConsoleHandler)
}
Here is my template.html
<html>
<head><title>{{.Title}}</title></head><body>
...
<h1>{{.Heading}}</h1>
<div id="gridviewcontainer">
<br />
<div id="gridtitle">
<a href="{{.GridTitleLink}}" style="font-size:25px;">{{.GridTitle}}</a>
</div>
<table id="gridtable">
<tr>{{range $ColumnIdx, $colheading := .ColumnHeading}}
<th>{{$colheading}}</th>{{end}}</tr>
<<!---This is what is causing the issue, .NumOfRows is not a valid field, must be array, channel, pipeline, or map -->
{{range $index, $rowval := .NumOfRows}}
<tr>
{{range $rowidx, $rowdat := .RowData}}<td>{{$rowdat}}</td>{{end}}
</tr>
{{endfor}}
</table>
...
</body>
</html>
I connect to the database correctly and using the "fmt" package I can print correctly. But I can't figure out how to loop through for number of rows retured in the html page. Is there a way to cast sql.Rows to a correct type or loop for a set integer number of times in html.
ps. I tried using {{ $index := 3}}...{end}} in the html, but that didn't work
Any input would be greatly appreciated
