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pkudrys's avatar
pkudrys
Contributor
9 months ago

DBTableVariableObj.Reset() not working as expected

Hi guys,  I'm experiencing a weird problem with DBTableVariableObj.Reset(), which is supposed to reset the iterator back to the first row. Well, it seems it does not reset the iterator at all :)  H...
Debugging
  • rraghvani's avatar
    rraghvani
    9 months ago

    What you are seeing is something called pass by value, as opposed to pass by reference. It means that JavaScript copies the values of the variables into the function arguments. 

    In this example, you would expect the value of myString to be changed to 'New String'. However, we are just passing the value,

    function myfunc(sameString) {
    sameString = 'New String';
}

function Test()
{
    var myString = 'Old String';
    myfunc(myString);
    Log.Message(myString);
}

    The same applies to what you have written. However, I would have expected Variables.testDBTable not to change at all, as you are "passing by value". But it seems like the object value is changing, as shown in this example,

    function increaseAge(obj) {
    obj.age += 1;
}

function Test()
{
    let person = {
      name: 'SmartBear',
      age: 25,
    };

    increaseAge(person);
    Log.Message(person.age);
}

    To reset your iterator, insert the following at the end of your function,

    KeywordTests.Test1.Variables.testDBTable.Reset();
rraghvani's avatar
rraghvani
Champion Level 3

What you are seeing is something called pass by value, as opposed to pass by reference. It means that JavaScript copies the values of the variables into the function arguments. 

In this example, you would expect the value of myString to be changed to 'New String'. However, we are just passing the value,

function myfunc(sameString) {
    sameString = 'New String';
}

function Test()
{
    var myString = 'Old String';
    myfunc(myString);
    Log.Message(myString);
}

The same applies to what you have written. However, I would have expected Variables.testDBTable not to change at all, as you are "passing by value". But it seems like the object value is changing, as shown in this example,

function increaseAge(obj) {
    obj.age += 1;
}

function Test()
{
    let person = {
      name: 'SmartBear',
      age: 25,
    };

    increaseAge(person);
    Log.Message(person.age);
}

To reset your iterator, insert the following at the end of your function,

KeywordTests.Test1.Variables.testDBTable.Reset();
pkudrys's avatar
pkudrys
Contributor
9 months ago

Hi rraghvani and thank you for the reply. The reset line you mentioned definitely helped! Thanks. 

But it's really weird :) I mean, at start of the function, there is created a new variable dbTable, which is filled from the function's parameter dbTableToRead. And then the while loop is performed on that new variable, not on the original parameter, containing the DBTable variable. And because there is no error thrown on dbTable.Reset; row, one would expect the initialization of the dbTable iterator was successful? I still think there is something wrong with the reset? :)  Anyway, thank you for the solution. 

  • rraghvani's avatar
    rraghvani
    Champion Level 3
    9 months ago

    I was almost about to give another explanations, and I've just noticed your statement dbTable.Reset; - you're missing the brackets. It should be dbTable.Reset();

    Now it should work, as you expect it too!

    • pkudrys's avatar
      pkudrys
      Contributor
      9 months ago

      Oh man, this is an error in TC user guide then... 

      I just copied it from there :D  Of course, Reset() works just fine. No need to reset the original table variable.