Finance | Project Operations, Human Resources, ...

how to call "form datasource" method from "field datasource" method

(3) Share

Report

Posted on by ..

1,979

Hi,

i put a method on formdatasource level as below

but it seems I can't call this method from the field DataSource level? as I'm getting this error:
ClassDoesNotContainMethod: Class 'FormDataSource' does not contain a definition for method 'xxx' and no extension method '' accepting a first argument of type '' is found on any extension class.

i tried four ways but all failed

1. How to fix it?

2. In general which way of the 4 is best to get formdatasource using CoC from ExtensionOf(formDataFieldStr?

2a. when do i use 'formRun' like this:

FormRun formRun = element;
FormDataSource table1_ds = formRun.dataSource(formDataSourceStr(Form1, Table1));

2b. when do i use 'element' like this

FormDataSource table1DataSource = element.dataSource(formDataSourceStr(Form1, Table1)) as FormDataSource;

2c. when do i use 'this' like this

FormDataSource table1_datasource = this.dataSource();

2d. when do i use 'formDataObject' like this

FormDataObject fdo = any2Object(this) as FormDataObject;
FormDataSource fds = fdo.datasource();

Categories:

Dynamics 365 Finance

I have the same question (0)

All responses (3)

Answers (0)

Suggested answer

Martin Dráb 238,123 Most Valuable Professional on at

Like (0)

Report
Copy link

Link copied!

There are more ways, such as element.Table1_ds, but this.dataSource() sounds the best to me if you want the data source of the form control.

You can declare the variable as Object to bypass the compile-time control, which might fix the problem, but it's not a good design and you'll likely get a compiler warning about it.

Personally, I would declare the method in a form extension (rather than a data source extension) and then call it simply like element.mySetField1Access().

Was this reply helpful? Yes No
.. 1,979 on at

Like (0)

Report
Copy link

Link copied!

Hi @Martin Dráb,

yes i tried "object" instead of formdatasource and it worked but a BP warning appeared as u said

1a. So it means it's not a best practice to call a datasource method from from a field datasource method? (I mean always field datasource methods need to call "form" methods or methods in the "field datasrouce" itself but not a "form datasource" method?)

1b. but why put it in form level, if it's only used for one datasource?

2. yes element.Table1_ds and this.dataSource() both worked, but yes i agree, using "this" sounds better as it will gurantee that it gets the field datasource, as if i use element.Table1_ds there might be a mistake where i write the wrong datasrouce

3. In general think i should always use element in CoC but maybe use formRun in event handlers? right?

4. when would I need to use FormDataobject like this? in which case?
FormDataObject fdo = any2Object(this) as FormDataObject;
FormDataSource fds = fdo.datasource();

Was this reply helpful? Yes No
Martin Dráb 238,123 Most Valuable Professional on at

Like (0)

Report
Copy link

Link copied!

1a. Correct.

1b. This thread is about the reason.

2 Good.

3. No, you shouldn't use element always. You should use it when you need it and it's possible. You must use it when you want to refer to the form from components that belongs to the form, such as data sources or controls. Event handlers (typically) don't have element variable, therefore it's not an option to consider.

4. Let me quote what I wrote elsewhere:

There is something wrong with this reference in form datasource field extensions.

For example, I created an extension of CustGroup.Name in CustGroup form. The type of this seems to be FormDataObject - I see it in debugger and get it from classIdGet() and GetType().

But I can't assign it to a variable with FormDataObject type. Compilation fails with Cannot implicitly convert from type '$FormDataField_CustGroup_Name' to type 'FormDataObject'.

If you try this as FormDataObject, the compiler claims that this isn't a class.

A workaround of assigning this to an Object variable and then to FormDataSource works. Therefore the object is really an instance of FormDataObject.

(I reported this in the preview program forum in 2022. Unfortunately, nothing has changed.)

Was this reply helpful? Yes No

Join the conversation

Community site session details

how to call "form datasource" method from "field datasource" method

Helpful resources

News and Announcements

Quick Links

Responsible AI policies

Neeraj Kumar – Community Spotlight

Congratulations to the November Top 10 Community Leaders!

Leaderboard > Finance | Project Operations, Human Resources, AX, GP, SL

Featured topics

Product updates

Community site session details

how to call "form datasource" method from "field datasource" method

Helpful resources

News and Announcements

Quick Links

Responsible AI policies

Neeraj Kumar – Community Spotlight

Congratulations to the November Top 10 Community Leaders!

Subscribe to this forum!

Select categories

Leaderboard > Finance | Project Operations, Human Resources, AX, GP, SL

Featured topics

Product updates