Wednesday, August 22, 2012

APEX Tabular Form: focus cursor on first element of new row

focus0I just got the question from a fellow developer, how to focus the cursor to the first input field of a newly added row using the ADD button in a standard APEX Tabular Form. Actually, I would expect APEX to do this automagically. But it doesn’t. To implement this behavior is actually really simple.

 

 

For this example I create a simple tabular form based on the demo_customers table:

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This is what the form looks like when you click the “Add Row” button. As you can see, none of the input field has focus at this time. To focus the cursor on the first field of the new row (Cust First Name), I somehow have to change the behavior of the “Add Row” button. Let’s have a look at it’s definition:

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The click-action of the button is actually a JavaScript call: addRow();. Naturally I want to keep this action, but after this, I want to start an additional action that should set the focus to the input field. To be able to have multiple actions performed when the button is clicked, I will change the Action definition to “Defined by Dynamic Action”:

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Now I’m going to add a Dynamic Action to the “Add Row” button. First action will be the original JavaScript call to add the row, second action will be setting the focus. This is how the definition will look like after I added the actions:

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Creating the Dynamic Action and the first True Action I will do with the Create Dynamic Action Wizard for the button:

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Now I have implemented the original behavior.

Next I want to focus the cursor on the first text-field of the added row, once I click the button. I know there is a build-in Dynamic Action to set the focus on an element. I just need to know which element. Let’s have a look at the HTML code of the generated APEX page, especially the the text-field element we wish to target (I used the Chrome Developer Tool here):

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As you can see, the name of this element is f02 and the id f02_0008. Because the ID can change depending on the number of rows displayed, I choose to work with the name attribute, which stays the same. The problem is, all “Cust First Name” fields do have the same name. Luckily jQuery offers a way to select the last element in an array of element with the same name and luckily, APEX Dynamic Actions support jQuery selector syntax. So here is, how I define the focus action for my “Add Row” button:

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As you can see, I select all elements having the name attribute equal to f02 and :last allows me to select the last element of these. Here is a screenshot from the result (after clicking the “Add Row” button) with focus on the first text element of the last, newly added row:

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