How does the writer decide what the data type is?

[JohnRoss]

I have a writer stage writing 3 items. Regardless of what the top item is, it will say in the Type column, "Unknown". It is a text data item, being written to a text input field in a web browser. I get the error Unable to cast COM object of type 'mshtml.HTMLDocumentClass' to interface type 'mshtml.IHTMLDocument3'. I can change the order of items listed. This always happens to the first item listed, no matter what it is. Any subsequent items work fine. How does blue prism decide what the type is? Isn't that based on the element rather than the type of data item? What criteria does it use? How can I check this?

[John__Carter]

The data type comes from the element. In application manager, what is the element type and data type of the field, are they HTML Edit and Text?

[JohnRoss]

Hi, John. Yes. They are all element type ""HTML Edit"" and data type ""Text"", yet it still says unknown for the first item in the list. I'm having a bit of trouble pinning down the issue here. If I add the writer elements in a different order, it's always the one on the top. That doesn't make a lot of sense to me. Neither does the error message. By the way, this only gives me an error about 20% of the time and only when running from control room. Never in debug mode. I think I have just done something silly and can't figure it out quite yet.

[John__Carter]

The 'occasionally and only in control room' effect is almost always due to timing and poor synchronisation. Control room execution is many times faster than the fastest diagram speed, and I would bet that somewhere your logic is running too fast and maybe trying to use the element too soon. Note that for web elements wait stages offer 'document loaded' and 'parent document loaded' conditions that are more appropriate than 'check exists'.