Drupal 8.x

Hi

I'm new in drupal 8, and I need help.

I am validating the upload of a file with "managed file" and I want to show a message when the user uploads a file with the wrong format. Currently when the user uploads a file with the wrong format it gets red in the title field, I like to show as a drupal set message or something similar.

I appreciate any help, thanks!

Hi everybody!

I have some difficulties in the installation of drush via composer!

I have a dedicated serveur running on ubuntu 14 . i want to install drush using composer on the server in order to be able to install any web site using drush!
but it don't work.
the root folder for web site on the serveur is "httpdocs".

when I run drush in this folder ("httpdocs") I get an error.

edit: project pending confirmation from developer

Hello, in the form of inserting a content I would like a field to be visible based on the selection of another field. To create this in drupal 7, I used the Field Conditional States module. For Drupal 8 I'm going to use the hook_form_FORM_ID_alter () function.

Using Drupal 8.3.7 I have a contact form set up using the core contact module (hurray!) but am unable to figure out how to have different topics go to different email addresses.  The docs say this is possible with the core contact module:

https://www.drupal.org/docs/8/core/modules/contact/overview

Hi,

Dealing with an exposed form that has a handful of filters. Using Drupal 8, this is my second Drupal site - and I'm not a developer.

I would like to incorporate a slider for some of the filters. Click here for an example. I've looked and some modules - but don't exactly know what terms to look for other than "slider" or "math slider".

Is this possible with css only? Do I need a module? I would not know where to start in creating a module myself.

Any advice is appreciated.

Thanks!