Category: Programming

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Installing Visual Foxpro on Windows 10 64bit

After replacing my computer, I needed to reinstall Visual Foxpro. I had the install disc contents, but whatever executable I started with: it kept on crashing. A Google search brought silly advice, but fortunately there was a gem: an article on wOOdy’s Blog. This explained what the right procedure is and what file to start with (VFPSTART.HTA). It stil would not work. Not from a folder, and not from a mapped network disc. I found the free AnyBurn software that gave me the opportunity to create an ISO file from my install folder. Now it was as easy as double clicking the ISO file to have Windows mount the CD image and assign it a drive letter. Now everything worked like a charm. Then we have to apply both service packs, and perhaps some useful suggestions wOOdy made.

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Foxpro ReturnObject

Function to prevent problems during object creation to crash your program. When problems arise, your program might be unable to continue, but at least you can show the user what went wrong instead of an uninformative crash warning.

* ReturnObject 
* 2011.05.31 start
* 2012.07.06 parameters added
* Tries to create an object and return this. If object creation failed, a false is returned
* Parameters: Class to instantiate object from, max 2 parameters
FUNCTION ReturnObject( tcClass,tuPar1,tuPar2)
 LOCAL loReturn,lnCount,loError
 lnCount = PCOUNT()
 TRY 
  DO CASE 
   CASE lnCount = 1
    loReturn = CREATEOBJECT(tcClass,tuPar1)
   CASE lnCount = 2
    loReturn = CREATEOBJECT(tcClass,tuPar1,tuPar2)
   OTHERWISE 
    loReturn = CREATEOBJECT(tcClass)
  ENDCASE 
 CATCH TO loError
  loReturn = .f.
 ENDTRY 
 RETURN loReturn 
ENDFUNC

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Foxpro and Excel

It is very possible to automate spreadsheets from Visual Foxpro using VBA/ COM automation. Here I wil document the parts I need.

Connecting to Excel

oExcel = CreateObject("Excel.Application")
if vartype(oExcel) != "O"
  * could not instantiate Excel object
  * show an error message here
  return .F.
endif

I use my own library (JLIB) containing a ReturnObject function that fetches errors. Using that function my code looks like this:

PUBLIC goX && global Excel object

IF InitiateExcel()
 * Code here
ELSE
 ? [Error initiating Excel automation]
ENDIF 


PROCEDURE InitiateExcel
 goX = ReturnObject([excel.application])
 RETURN (VARTYPE(goX)=[O])
ENDPROC

Open an existing spreadsheet

oWorkbook = oExcel.Application.Workbooks.Open("C:\temp\test.xls")

Create a new blank spreadsheet

oWorkbook = oExcel.Application.Workbooks.Add()

Create a new spreadsheet from a template

oWorkbook = oExcel.Application.Workbooks.Add("C:\temp\template.xlt")

Sheets collection/ objects

oWorkbook.sheets.count && returns the number of tabs/ sheets 
oSheet = oWorkbook.sheets(1) && get an object to control the sheet
? oSheet.name && show the sheet name

Tables

A table is called a ListObject in Excel/ Microsoft terminology

oSheet.ListObjects.count && gives the number of tables on the sheet
oTable = oSheet.ListObjects(1) && get an object to control the table
? oTable.ListRows.count && displays the number of data rows in the table
oTable.DataBodyRange.delete && deletes al rows. Error (crash) if there are no rows!

Working with table rows

Adding a table row needs several steps: 1. Add the row and keep the reference to it. 2. Add the column data 1 by 1:

oRow = oTable.ListRows.Add && you have a new row and a reference to it
oRow.Range(1) = Date(2020,7,6) && Add a date in the first column

Using named cells

? oSheet.Range("ProductionDate").value && show value of cell named ProductionDate
oSheet.Range("TotalPages").value = 13

Saving and closing

The save method is in the workbook object. And you can quit from the Excel application object:

oSheet.SaveAs([x:\reports\report.xlsx]) && Save
oExcel.Quit && quit Excel

The Quit only works on this Excel application you’ve initiated. So existing opened Excel sheets are untouched (remain opened).

Sources used

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OpenXava rapid web development

This Java based development framework makes developing a (enterprise) web app as easy as defining your data model. Your main task is to create a good data model, pour it into classes, and defining the relationships and referential integrity. The framework creates the web app for you! When you are ready to deploy, the web app can be hosted in a Tomcat environment.

https://www.openxava.org/

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Node.js: Application as a Windows service

node-windows

node-windows is a standalone module that makes it possible to offer a Node.js script as native Windows services..

Prerequisite: You have succesfully installed Node.js.

Install with npm using the global flag:

npm install -g node-windows

In the project root run:

npm link node-windows

Hello world example

Create a hello.js file with this code (Hello World sample from the Express website):

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => res.send('Hello World!'))

app.listen(port, () => console.log(`Example app listening at http://localhost:${port}`))

You can (should) test if it works by running it from the command line:

node hello.js

If there are no errors, point your browser to http://localhost:3000. If it says Hello World! you are well on your way!

Script to create the service

Now we have our app, we want to make it a service. This is achieved by another script we call hello-windows-service.js:

var Service = require('node-windows').Service;

// Create a new service object
var svc = new Service({
  name:'Node app hello',
  description: 'Node app hello as Windows Service',
  script: 'C:\\npm\\.node_modules_global\\hello.js'
});

// Listen for the "install" event, which indicates the
// process is available as a service.
svc.on('install',function(){
  svc.start();
});

svc.install();

Most important is the correct location of the script in the Service call..
Now run this script to install the service into Windows:

node hello-windows-service.js

Now if you check your services, I hope you’ll find this:

Great! The Node app is running as a Windows service under a local system account. The app is running even when nobody is logged in. Goal achieved. Oh and because it’s on Automatic start, it wil always become available after each server restart.

Based on this article by Peter Eysermans.

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m1m0 learn to code

An article in Computer Totaal mentioned this App. It is said to be a kind of game to learn programming bit by bit. By solving puzzles you gain points, thus rewarded for learning. The App gives you languages like HTML, CSS, SQL, Java, Python, Ruby, C++ and more. I haven’t tried it yet, but it looks like fun.

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React: build for relative paths

If it’s not a real production build, you probably test your React Apps in a sub folder at your hosting space. The information on this is scattered and explained way too difficult. There’s nothing to it:

  1. Open package.json in uour App root folder
  2. Find the parameter “homepage” or add it (image above)
  3. Give the parameter the value of the complete path where your app will be hosted (image above)
  4. Save the package.json file
  5. Build the React app using npm start build
  6. Upload the production build (folder build) to your hosting provider
  7. And done!

And when you are building the React App using npm run build, it should confirm the subfolder: