Dynamic field content

Classic Servoy
1

Hello, I am trying to let the user choose which fields he wants to have on a form (in a certain area). For example, one user wants to see the total sales, another wants to see the birthday.

I think I have done that before, but see no way right now. The idea is to let the user store up to e.g. 5 field names in his preferences and those five fields are then populated with the data of the fields that the user chose.

Any idea on how to this?

Thanks
Patrick

2

Oops, just found a way: if you have a calculation of the type

var field_1 = data_to_user.field_choice_1
return [field_1];

some sort of java object is returned. But when you use a self-relation like this

var field_1 = data_to_user.field_choice_1
return data_to_data[field_1];

then it works. Why isn’t the first approach coming up with the same result?

Thanks
Patrick[/quote]

3

why should it?
you do there something completely different!

What are you exactly returning?

Which colum of which related data are you trying to show?

4

Let’s say you have 3 fields “name”, “street”, “city”. In a user table you have a field “field_choice_1”. In that field the user chooses “street”. I now want to be able to display the content of the column “street” in a field. The problem is, that I have no option to dynamically set the dataprovider of a field.

First I tried with [field_choice_1] and was trying to get Servoy to display the contents of the field “street”.

Since that didn’t worked, I made a self-relation on my table from pk to pk. Then I tried with self-relation[field_choice_1] and now am able to see the field contents based on what the user chose to see.

My question was: what is the difference between [field_choice_1] and self-relation[field_choice_1].

Did I make myself understandable?

Thanks
Patrick

5

ahh i see. in a calculation you don’t have the controller.getDataProviderId().

But just calling [name] is illegal. That is not possible you have to have a context. maybe return this[name] works but i am not sure.

6

this[name] gives you

Exception executing field_choice: Cannot convert null to an object.

So the way I do it (using the self-relation) is the way to do it?

Thanks
Patrick

7

hmm. just saw that “my way” throws the same error but shows you the correct result. Should I worry about the error :wink:

8

Would this work for you?

return currentcontroller.getDataProviderValue(field_choice1)

Another way would be of course writing an event script attached to onShow ect.

9

That is a very interesting suggestion, because probably nobody knew, that you could “talk” with a controller from a calculation. But yes, you can. It does work this way as well!

But it also throws an error “cannot convert…” as my way above. Does this need a fix from Servoys side or can I do something to avoid the error? The results are great, anyway :P

10

try this:
if(field_choice1)
{
return currentcontroller.getDataProviderValue(field_choice1)
}

this checks of the field: field_choice1 is empty or null
than I think, you don’t get the error!

11

yes I tried. The problem is that the error is only thrown if field_choice has a value. If it is null there is no error.

12

first of all
using currentcontroller is very dangerous.
Because what happens if that calculation is on another form (completely not displayed or displayed in a tab??)

Then the currentcontroller doesn’t point to the table of the calculation.

about that error. I don’t know exactly when that error is exactly generated. Because you do say that it works?? You do see the right value?
Then this is very strange.

i need to have/make an example to see that.

can’t you try a eval function for this? (but i don’t know if eval will return something.. have to check:

return eval(field_choice1)
(something like that)

13

I thought that you didn’t enjoy me discover that you could use currentcontroller :wink:. I thought there was a good reason you left controller methods out of the calculation area and I do see the point.

But then: eval also works. But also throws an error. I will make an example solution so you can see what happens.

Thanks.
Patrick

14

Just figured out that the error thrown just occurs in conjunction with the method I use to choose the field. I just changed something there and now it works like a charm.

Thanks for your input. Basically all of the suggestions (including my own) seem to work smoothly.

Patrick