Validation of standard link types

[maxime-rainville]

Story

As a content author, I want LinkField to block me from inputting invalid data.

Acceptance criteria

• Appropriate logic is applied - e.g. external links must have a URL, page links must have a Page, etc.
  • PageLink should have a page
  • EmailLink should have a valid email address
  • External link should have a valid full URL
  • Phone link should have a non blank string but not otherwise validate the phone number
  • File link should point to a valid CMS file.
• We use form validation for validating the data.
• The LinkField doc is updated to link to the form validation article in the main doc.

Exclude

• Displaying the validation error in a front end. Front end validation  #16

Guy's PRs

• NEW Wire up symfony/validator silverstripe-framework#11123
• DOC Document using symfony/validator developer-docs#454

Steve's PRs

• NEW Add UrlField silverstripe-framework#11116
• ENH Improved validation #85
• DOC Add UrlField developer-docs#450

[maxime-rainville]

We have already partially implemented this in the process of re factoring bits of the linkfield.

Maybe this card just become a doc card.

[GuySartorelli]

PRs merged