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Deleting data with ORM

From: ColdFusion 9 Essential Training

Video: Deleting data with ORM

In the current state of my index.cfm page in my Photographers folder of the application, I'm letting the user click a link to select a record to delete. I'm then using the ColdFusion MessageBox tool to let them confirm or cancel the operation. To actually delete the data from the backend database, I'm going to cause the page to navigate to a separate page that will execute an ORM function that removes the data from the backend database table. I will start an index.cfm in the doDelete callback function.

Deleting data with ORM

In the current state of my index.cfm page in my Photographers folder of the application, I'm letting the user click a link to select a record to delete. I'm then using the ColdFusion MessageBox tool to let them confirm or cancel the operation. To actually delete the data from the backend database, I'm going to cause the page to navigate to a separate page that will execute an ORM function that removes the data from the backend database table. I will start an index.cfm in the doDelete callback function.

I currently have a call to the JavaScript alert method there, which is just reporting which button was clicked. I will comment that code out, placing a pair of slashes at the beginning of the line and then I will place the cursor on a new line. I'll start with an if clause. I'll check the value of the btn variable for a value of Yes. Remember the JavaScript returns this value as all lowercase, so it will be either yes or no lowercase.

And then, I'll create a pair of curly braces and if that condition is true, I will then navigate to a new page and pass the value of the photographer ID that was selected by the user. I will use this JavaScript code, document.location =, and then I will pass the name of a ColdFusion page that I need to create, delete.cfm. This page will expect a variable called photographerid in the URL scope. So, I will add a question mark after the page name and the name of the variable, photographerid, and an equals operator.

Then I'll put a plus operator at the end of the line after the quote. In JavaScript you use the plus operator for concatenation. That's in contrast to ColdFusion, which uses the ampersand and then I will pass in the value of the JavaScript photographerid variable that I created and populated earlier. I will copy it to the clipboard and I'll paste it in this code location. If the user clicks the Yes button on the confirmation dialog, I'll activate this bit of code that goes to the delete page.

I'll test this code in an external browser. I'll save my changes and then click the Run button on the toolbar. I will click the delete link and click Yes and take a look at the URL in the browser, delete.cfm?photographeri =, and then the primary key of the selected record. So, I'm on the right track. I need to create the delete page, which will delete the data from the backend database. I will close the external browser and return to ColdFusion Builder.

I will go to the Navigator view, to the photographer's folder of the Photo Gallery application. I will right-click on it and choose New > ColdFusion Page and I'll name my new file delete.cfm. The user will never see this page. It will be purely a backend page that's called, executes its functionality and then returns the user back to the list page. So, it doesn't need any HTML. I'll select all of the default code by pressing Ctrl+A on Windows or Command+A on Mac and then pressing Delete or Backspace.

Then I will create a pair of cfscript tags. Here are the tasks I need to accomplish. First, I need to discover whether the variable photographerid was passed to this page. I will use an if command. If and then, under pair of parentheses, isDefined and then I will pass in the name of the variable as a string that I'm looking for. url.photographerid. Then within a pair of curly braces, if I received that variable, I will retrieve the matching data object from the backend database, using this code, photographer = entityLoadByPK, and I'll pass in the name of the entity I am looking for, Photographer, and the primary key that I received in the URL variable url.photographerid and I will make sure to add a semicolon at the end of the line.

I have my photographer object in memory and I can call another ORM method, this one named entityDelete, which expects an ORM object. I will call entityDelete and pass in the photographer variable. And once again, terminate the statement with a semicolon. At the end of the if clause, below the closing brace, I will use ColdFusion 9's new location method and I'll pass in the name of the page I want the user to go to index.cfm.

When this page is loaded into the browser, if the photographerid variable is passed in the URL scope, the matching data will be deleted from the database table. If that variable is not passed in, then these two lines of code will be ignored and either way the location function will send user back to the beginning page index.cfm. I will save my changes and I'll go back to the list page, index.cfm, and now I'm ready to test the whole workflow. I'll save any changes I need to save and then I'll load the page into the browser.

I will click the delete link for one of my new records. I will delete Joe Jones. The first time I will click No and confirm that nothing bad happens. Because I clicked No, I canceled the operation. I will click the delete link again and this time I will click Yes and the browser navigates to the delete page invisibly, deletes the data and then immediately navigates back to the list page and I can see that the data was successfully deleted. I will click the delete link for John Smith and click Yes again, and I can see once again that the data is gone.

So, those are all of the pieces of a good delete operation. Make sure that you give the user an opportunity to cancel the operation. If you simply delete data as result of a single click, it's too easy to make a mistake for the user. You allow them to confirm or cancel the operation and then use a separate page to actually do the delete operation.

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This video is part of

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ColdFusion 9 Essential Training

95 video lessons · 9854 viewers

David Gassner
Author

 
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  1. 5m 54s
    1. Welcome
      1m 24s
    2. Using the exercise files
      2m 50s
    3. Overview
      1m 40s
  2. 35m 16s
    1. Understanding application servers
      7m 3s
    2. Installing ColdFusion 9 on Windows
      5m 28s
    3. Installing ColdFusion 9 on Mac OS X
      6m 20s
    4. Completing the Configuration wizard
      1m 50s
    5. Starting and stopping ColdFusion on Windows
      4m 7s
    6. Starting and stopping ColdFusion on Mac OS X
      2m 37s
    7. Installing ColdFusion Builder on Windows
      4m 13s
    8. Installing ColdFusion Builder on Mac OS X
      2m 1s
    9. Setting folder permissions on Mac OS X
      1m 37s
  3. 45m 34s
    1. Using Eclipse perspectives and views
      5m 42s
    2. Defining a ColdFusion server
      8m 42s
    3. Creating a ColdFusion project
      4m 40s
    4. Creating and browsing a ColdFusion page
      5m 36s
    5. Defining a default page template
      3m 58s
    6. Setting and outputting variables
      7m 55s
    7. Using the Snippets view
      4m 49s
    8. Using an external browser
      2m 8s
    9. Using online help
      2m 4s
  4. 35m 48s
    1. Adding numbers and concatenating strings
      8m 7s
    2. Using Debug Output
      6m 10s
    3. Inspecting variables with ‹cfdump›
      4m 54s
    4. Using arrays
      5m 21s
    5. Using structures
      3m 51s
    6. Configuring the line debugger
      1m 25s
    7. Using the line debugger
      6m 0s
  5. 53m 45s
    1. Scripting an Apache Derby database
      3m 34s
    2. Defining a data source in ColdFusion Administrator
      6m 13s
    3. Exploring data sources in RDS Dataview
      4m 2s
    4. Using SQL and the ‹cfquery› tag
      6m 58s
    5. Outputting data from a query object
      4m 2s
    6. Outputting a dynamic HTML table from a query
      7m 0s
    7. Generating alternating row colors
      6m 55s
    8. Creating an application directory and home page
      5m 26s
    9. Displaying data on the home page
      5m 43s
    10. Redirecting requests with ‹cflocation›
      3m 52s
  6. 32m 17s
    1. Including pages with ‹cfinclude›
      4m 21s
    2. Creating reusable header and footer files with ‹cfinclude›
      4m 39s
    3. Creating and calling custom tags
      3m 8s
    4. Passing data into custom tags
      2m 34s
    5. Setting default values for custom tag attributes
      4m 51s
    6. Calling custom tags with ‹cfmodule›
      3m 54s
    7. Using a custom tag as a website header
      3m 55s
    8. Creating an application template file
      4m 55s
  7. 52m 6s
    1. Creating a ColdFusion Component (CFC)
      5m 6s
    2. Declaring CFC functions
      3m 28s
    3. Calling CFC methods with ‹cfinvoke›
      2m 28s
    4. Using CFC properties
      4m 51s
    5. Passing data into functions
      3m 38s
    6. Creating and calling CFCs with script syntax
      5m 25s
    7. Generating data access CFCs in ColdFusion Builder
      4m 35s
    8. Calling generated data access methods
      7m 41s
    9. Creating a dynamic HTML table from an array
      8m 8s
    10. Creating an Application.cfc file
      3m 11s
    11. Using an application data source variable
      3m 35s
  8. 32m 56s
    1. Generating an ORM map component
      7m 58s
    2. Enabling an application to use ORM
      1m 58s
    3. Retrieving data with ORM
      2m 55s
    4. Generating mappings for multiple tables
      4m 22s
    5. Filtering data with ORM
      5m 35s
    6. Displaying result data with a custom tag
      10m 8s
  9. 27m 58s
    1. Passing URL variables in hyperlinks
      6m 13s
    2. Passing multiple URL variables
      2m 50s
    3. Encoding URLs with URLEncodedFormat()
      4m 12s
    4. Checking for available variables with isDefined()
      2m 41s
    5. Creating a data-driven hyperlink
      5m 4s
    6. Displaying selected data in a detail page
      6m 58s
  10. 40m 36s
    1. Using HTML data entry forms
      6m 53s
    2. Processing form variables
      3m 24s
    3. Creating self-posting forms with ‹cfform›
      4m 40s
    4. Creating a search interface
      3m 9s
    5. Processing complex queries with HQL
      8m 53s
    6. Creating a dynamic pulldown list with ‹cfselect›
      7m 16s
    7. Displaying form results
      6m 21s
  11. 43m 46s
    1. Building a data entry form for managing data
      5m 15s
    2. Preparing an ORM mapping for inserting data
      3m 47s
    3. Inserting data with ORM
      5m 23s
    4. Retrieving data for an update form
      4m 16s
    5. Populating form controls with existing data
      5m 2s
    6. Updating data with ORM
      2m 56s
    7. Confirming actions with an Ajax message box
      7m 22s
    8. Using JavaScript callback functions
      3m 15s
    9. Deleting data with ORM
      6m 30s
  12. 9m 37s
    1. Defining client-side form validation rules
      4m 14s
    2. Validating on the server with custom CFML
      5m 23s
  13. 18m 9s
    1. Using the Application.cfc onRequest() method
      4m 12s
    2. Creating and using a login form
      4m 53s
    3. Authenticating users with ‹cflogin›
      6m 1s
    4. Logging out users
      3m 3s
  14. 7m 11s
    1. Configuring an FTP site
      2m 27s
    2. Setting a ColdFusion project's synchronization connection
      2m 17s
    3. Uploading files to the production server
      2m 27s
  15. 46s
    1. Goodbye
      46s

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