subscribe to fieldChanges and get no change from expressionProperties

[GlauberF]

Description
within a type(table) I need to be notified when the field changes, using formly's expressionProperties property.
my implementation in the field:

I tried to use the following listener within the type (table):

this.options.fieldChanges.subscribe(el => {
     console.log('fieldChanges', el);
});

however, I am only notified when there is a change of type "hidden"

I don't know if it's a bug, but I believe it should be notified or if there is another way to hear these changes made by expressionProperties

Your Environment

Angular CLI: 10.0.1
Node: 12.18.1
OS: linux x64

Angular: 10.0.2
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... platform-server, router, service-worker
Ivy Workspace: Yes

Package                            Version
------------------------------------------------------------
@angular-devkit/architect          0.1000.1
@angular-devkit/build-angular      0.1000.1
@angular-devkit/build-optimizer    0.901.1
@angular-devkit/build-webpack      0.1000.1
@angular-devkit/core               10.0.1
@angular-devkit/schematics         10.0.1
@angular/cdk                       10.0.1
@angular/cli                       10.0.1
@angular/flex-layout               9.0.0-beta.29
@angular/material                  10.0.1
@angular/material-moment-adapter   10.0.1
@ngtools/webpack                   10.0.1
@nguniversal/builders              10.0.1
@nguniversal/common                10.0.1
@nguniversal/express-engine        10.0.1
@schematics/angular                10.0.1
@schematics/update                 0.1000.1
rxjs                               6.5.5
typescript                         3.9.6
webpack                            4.43.0

formly                               5.7.1

[dottodot]

I have a similar issue as I want to render a template that contains a value from the form but expressionProperties doesn't update when the model changes.

            fieldGroup: [
              {
                type: 'html-template',
                templateOptions: {
                  template: '',
                },
                expressionProperties: {
                  'templateOptions.template': (
                    model,
                    formState: any,
                    field: FormlyFieldConfig
                  ) => {
                    // This needs to update when the name field is changed.
                    return `<p><strong>${
                      field.parent.parent.model.name
                        ? field.parent.parent.model.name.toUpperCase()
                        : ''
                    }</strong></p>`;
                  },
                },
              },
            ],

[aitboudad]

@dottodot not related to this issue, please create a new issue with a reproduction using our starter example https://stackblitz.com/edit/ngx-formly-ui-bootstrap

[aitboudad]

This issue has been fixed and released as part of v5.9.0 release.

The fieldChanges now include expressionChanges event which emit the following object:

{
  field,
  type: 'expressionChanges',
  property: 'templateOptions.label', // expression property
  value, // expression value
}

Please let us know, in case you are still encountering a similar issue/problem.
Thank you!

[GlauberF]

thank you very much @aitboudad