mrc Documentation
michaels, ross & cole, ltd.
http://www.mrc-productivity.com/

Creating Drop-Down Lists from an External File (For use with Maintenance Applications)

Often times, especially when making a maintenance application, you would like a user to specify a value from a drop-down list. Let’s say you have an order entry screen and as customer’s add new orders they need to specify a ship-to state. Using the standard “A” or “D” in the User Defined Field Control (as you do with Reports and Retrievals) is impractical because this method queries the file to populate the list (What would happen if you wanted to ship to Colorado, but no one was in the database from Colorado? – Colorado would not be on the list). The answer is to create a drop down list from an external file. Below we will walk through the entire process. Note: The process outlined below is only for users of the Classic Web/Servlet Templates. If you are using Web 2.0 templates, you should follow this document.

Overview

Step 1 – Build External Object Inquiry over State File

Step 2 – Build the External Object Reference under the Data Dictionary Tab

Step 3 – Map the Correct Parameter

Step 4 – Call the External Object from a Maintenance Application

Note: Steps 1 through 3 only need to be done once. All future applications can utilize this object for a drop down list. The only step that needs to be repeated each time is Step 4.

Step 1

Our first step is to build the External Object Inquiry over our file that contains the data for our drop down list. For this example it is the STATES file. After I select my “STATES” file, I need to select two fields – The name of the state and the abbreviation. After sequencing, select Preformat. We need to tell this object which values will be the “D”escription and which will be the “V”alue. That is, I wish for our end user to see the entire name of the state but when the data is written to the file, I only want the abbreviation.

Be sure to select the “External Object Inquiry.” Build/Compile your Object.

Step 2

Since our object is now successfully created, we need to register it within the m-Power environment. To do this, click on the Data Dictionary tab and click the “Manage External Objects” link. Click the “Create” button.

Create your Drop-Down List based upon the screen shot above.

Note: Object Type must be set at M, as this is a Java Method.

The class name, HURCKES.I01905s, is the address of the object we created in Step 1.

The Method name,

For Drop-Down List output: getSelect("Select a State", pName, pValue, "select", 1)

This tells the external object how to behave. You can change “Select a State” to whatever text you want your dropdown list to have by default. You can also choose to have your output as a radio button by changing “select” to radio (Note: If choosing radio button, be sure to increase the 1 to a greater number, as this value determines how many buttons are listed per row):

For Radio Button output: getSelect("Select a State", pName, pValue, "radio", 10).

Click Accept.

Step 3

Now since we have our External Object registered, we must register the parameter that will be passed from the maintenance application to our application we built in Step 1.

Search for the object you just created, and click on the “Parameters” link for this object.

Since the field that we specified as the “V”alue field in Step 1 is a 2A field, this parameter must also be 2A.

Remember: The parameter you create must match the attributes of the field you specified as a “Value field in Step 1.

Click Accept.

Step 4

Now that we have created our External Object, Referenced it, and created the parameter it is time to create the Maintainer application that will use it.

After you have selected the proper file, fields, and sequencing, select the “External Objects” link.

Based on the screen above, you can see we are calling the Object we referenced in Step 2, passing along the parameter we defined in Step 3. Also notice that the location we are using is entitled *Select. This location is needed to create the Drop-Down list (or Radio buttons).

Click the Accept Button.

When the Application is run, we are shown this screen. Note: Notice the “Select a State” text, this is seen because we specified it when we created the reference to this object.

Clicking on the drop down, I am shown the following screen:

So, even though I entered my data like this:

The actual data in the file (queried with a basic Work-With Maintainer) looks like this:

Notice the data in the file was written as “CO” rather than “Colorado.”