Do you have a value, Mr. BLOB?

To check if a BLOB field has a value, you call its HASVALUE function. For example: IF Item.Picture.HASVALUE THEN;

In older versions, earlier than NAV 2009, you had to call CALCFIELDS before you could check HASVALUE, which – if you think of it, did not make much sense. This was changed in NAV 2009, so ever since that version you can check HASVALUE before you decide to call CALCFIELDS first. It makes all the sense – you don’t need to pull up to 2GB of data over just to see if anything is inside.

If you are an old-school guy (or just old, as me), and you CALCFIELDS first, HASVALUE next, maybe it’s time for you to reconsider it.

Rembember – the pattern is: IF Field.HASVALUE THEN Rec.CALCFIELDS(Field);


Vjeko has been writing code for living since 1995, and he has shared his knowledge and experience in presentations, articles, blogs, and elsewhere since 2002. Hopelessly curious, passionate about technology, avid language learner no matter human or computer.

This Post Has 7 Comments

  1. lvanvugt

    Unfortunately MS doesn’t use this useful change of behavior of HASVALUE. Have a look at the new table 9651 (Custom Report Layout) function UpdateWordLayoutXML@5:


  2. devch

    Nice to know! But just to be clear about that: what performance gain do you receive bei checking for value if you get it anyway if it has a value? if its empty, nothing is transfered by calling calcfields, if its not empty its transferred anyway, or am I missing something?

    Of course it makes sense if you realy just want to check, lets say on a page to indicate if the record has a value. But in a code routine?

    1. Vjeko

      Devch: You have just given the answer. Sometimes, you just want to know if the value is in there (e.g. showing a checkbox in a list page to indicate that a picture is present), and you don’t want to pull all 2 GB of data that each blob might contain, just to do that. In more than 90% situations, though, it doesn’t really matter which way you do it.

  3. Vincent Vancalbergh

    This saved me just now in NAV 2015. I was adding a BLOB field to Excel Buffer to be able to read larger texts. The writing worked great, but reading would always fail to return the data. I was doing:

    __CALCFIELDS(“Cell Value as BLOB”);

    __”Cell Value as BLOB”.CREATEINSTREAM(MyInStream);
    __IF NOT MyInStream.EOS THEN

    By moving the CALCFIELDS after the second HASVALUE it worked !

  4. Robert

    Thanks again.

    As always I keep finding my way here.

    1. Vjeko

      Glad I helped 🙂 And sorry for being so late with my replies 🙂

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