# 4.4.0 (Unreleased)

## Overview {#overview}

 - [Optional migration to hash-less public asset URLs](#hash-less)
 - [Optional migration of legacy thumbnail locations](#legacy-thumb)
 - [Correct PHP types are now returned from database queries](/developer_guides/model/sql_select#data-types)
 - [Server Requirements](/getting_started/server_requirements/#web-server-software-requirements) have been refined:
   MySQL 5.5 end of life reached in December 2018, thus SilverStripe 4.4 requires MySQL 5.6+.  
   SilverStripe 4.3 and prior still support MySQL 5.5 for their own lifetime.
 - The name of the directory where vendor module resources are exposed can now be configured by defining a `extra.resources-dir` key in your `composer.json` file. If the key is not set, it will automatically default to `resources`. New projects will be preset to `_resources`. This will avoid potential conflict with SiteTree URL Segments.
 - dev/build is now non-destructive for all Enums, not just ClassNames. This means your data won't be lost if you're switching between versions, but watch out for code that breaks when it sees an unrecognised value!
 - Removed `File.migrate_legacy_file` config option. Migration tasks now need to run via `dev/tasks/`,
   running them as part of `dev/build` is no longer supported

## Upgrading {#upgrading}

### Adopting to new `_resources` directory

The name of the directory where vendor module resources are exposed can now be configured by defining a `extra.resources-dir` key in your `composer.json` file. If the key is not set, it will automatically default to `resources`. New projects will be preset to `_resources`.
This will avoid potential conflict with SiteTree URL Segments. 

1. Update your `.gitignore` file to ignore the new `_resources` directory. This file is typically located in the root of your project or in the `public` folder.
2. Add a new `extra.resources-dir` key to your composer file.
```js
{
    // ...
    "extra": {
        // ...
        "resources-dir": "_resources"
    }
}
```
3. Expose your vendor assets by running `composer vendor-expose`.
4. Remove the old `resources` folder. This folder will be located in the `public` folder if you have adopted the public web root, or in the root of your project if you haven't.

You may also need to update your server configuration if you have applied special conditions to the `resources` path.

### Optional migration tasks: Overview

SilverStripe 4.x introduced an [asset abstraction](https://docs.silverstripe.org/en/4/developer_guides/files/file_storage/)
system which required a [file migration](https://docs.silverstripe.org/en/4/developer_guides/files/file_migration/) task.

We have ironed out some edge cases since then:

 * [Hash-less public asset URLs](#hash-less)
 * [Legacy thumbnail locations](#legacy-thumb)
 * TODO Shortcode migration

 
You can opt-in to performing these migration tasks on your already upgraded SilverStripe 4.x project.
Projects which are upgraded from 3.x to 4.4 or newer will run these tasks by default.
You can perform these tasks in the background without CLI access by installing and configuring
the [queuedjobs](https://github.com/symbiote/silverstripe-queuedjobs) module.

### Optional migration tasks: Hash-less public asset URLs {#hash-less}

It allowed files to be access protected, have a separate draft stage,
and track changes to file metadata and their contents through the `Versioned` system.

This change defaulted to adding a content "hash" to file paths,
unless the migration was performed with `legacy_filenames=true`.
The hash would be updated when file contents change, and any link generated
through SilverStripe (e.g. through `HTMLText` or `$Image` template placeholders)
would automatically adjust. However, any direct links from search engines, bookmarks, etc would break.
This limitation was pointed out in the [upgrading advice](4.0.0#asset-storage) to developers,
but the impact wasn’t sufficiently highlighted. 

SilverStripe 4.3.2 introduced a redirect to fix those broken links.
Dynamic redirects are more resource intensive than serving static files.
With SilverStripe 4.4.0, we're providing an optional migration script
to move public files into their "hash-less" locations, removing the need for most redirects.
The original "hashed" file paths continue to work through redirects.
In order to opt-in to moving these files, run the following command:

```
vendor/bin/sake dev/tasks/MigrateFileTask
``` 

Further information is provided in the [Hash-less Public Asset URLs FAQ](#hashless-faq) below,
as well as the [Github issue](https://github.com/silverstripe/silverstripe-versioned/issues/177).

### Optional migration tasks: Legacy thumbnail locations {#legacy-thumb}

Alongside the new [asset abstraction](https://docs.silverstripe.org/en/4/developer_guides/files/file_storage/),
we've also changed where thumbnails are [stored](/developer_guides/files/file_storage#variant-file-paths).
The file format is now generalised as a "variant", and no longer lives in a `_resampled` folder.
Prior to this release, these thumbnails were left in place. For thumbnails generated
through PHP or template code, these are generated on demand in their new location,
causing duplication and unnecessary storage space.

You can opt-in to moving these legacy thumbnails to their new locations
with a subtask of `dev/tasks/MigrateFileTask`. If newer thumbnails have been generated,
it'll keep those. New migrations from 3.x to 4.x will include this migration step by default.

```
vendor/bin/sake dev/tasks/MigrateFileTask only=move-thumbnails
```

Note that as part of the [hash-less public asset URLs](#hash-less)
introduced in this release, requests to these legacy thumbnails will automatically redirect to
their new locations. Review the [Github issue](https://github.com/silverstripe/silverstripe-assets/issues/235)
for more details. 

### Hash-less Public Asset URLs FAQ {#hashless-faq}

#### How are files named and renamed?

Here's an example of how file names changed during an initial 4.x migration, and when upgrading to 4.4:

 * Original file created under SS 3.x: assets/myfile.pdf
 * File migrated under SS 4.x with `legacy_filenames=false`: `assets/[content-hash]/myfile.pdf` (Regression: links to `assets/myfile.pdf` no longer work)
 * File migrated under SS 4.x with `legacy_filenames=true`: `assets/myfile.pdf`
 * File with updated file content under SS 4.x: `assets/[new-content-hash]/myfile.pdf` (Regression: links to `assets/[content-hash]/myfile.pdf` no longer work)
 * File with hotfix applied (SS 4.2.3): `assets/myfile.pdf` and `assets/[old-content-hash]/myfile.pdf` redirects to `assets/[new-content-hash]/myfile.pdf`
 * File with full fix applied (SS 4.3.x) : `assets/myfile.pdf` and `assets/[old-content-hash]/myfile.pdf` redirects to `assets/[new-content-hash]/myfile.pdf`
 * Newly uploaded file with full fix applied (SS 4.4.0): `assets/my-other-file.pdf` (no redirect required)
 
More details on how files are stored can be found in the
["File Storage" guide](/developer_guides/files/file_storage).

#### How are redirects handled?

Redirects from (now legacy) hashed public URLs default to `301 Permanent Redirect`.
By opting into the [file migration to hash-less public URLs](#hashless-urls),
you can minimise these redirects. SilverStripe will automatically generate hash-less public URLs regardless,
but external links might still point to legacy hashed public URLs.
If you have a high traffic site with lots of direct references to asset URLs
(e.g. search engines indexing popular PDF documents),
we recommend that you configure HTTP caching for these redirects
in your webserver (e.g. through `.htaccess`).

The redirect code can be configured via `FlysystemAssetStore.permanent_redirect_response_code`.

If you upgrade an older SilverStripe 4 project to SilverStripe 4.4 and choose not to run the file migration task, 
your files will still be stored under an "hash" folder. Browsers who try to access this file via the "hashless" url will
be redirected to the "hash" URL with a `302 Temporary Redirect`.

The temporary redirect code can be configured via `FlysystemAssetStore.redirect_response_code`.

#### Do I need to regenerate HTML with existing links to assets?

Pages and other views can contain links to asset locations,
e.g. as HTML content rendered with `<img>` and `<a>` tags.
These might point to old locations of files (prior to running the optional migration).
While SilverStripe will automatically fix these references the next time the view is rendered,
this content is often cached (e.g. in a CDN).

We have implemented an automatic redirect for URLs pointing to asset
locations prior to running the optional migration script,
so there is no need to regenerate any content.
 
#### Is there any data loss or data integrity issue?

There are no known issues around data integrity.
All files that were available on a SS 3.x site are still available after upgrading to SS 4.x.

#### Will this change affect my search engine ranking?

As long as your files are still linked on your website, 
search engines will pick up the new links on any projects which have already been migrated.
The 4.3.2 bugfix will redirect links, which passes on any SEO rankings to the new link location.
Since links to files should be permanent after the bugfix has been applied,
this can lead to improved search engine rankings (since existing files under new links don’t need to be re-ranked by search engines).

#### Can I migrate away from the legacy_filenames=true option?

Yes. Simply disable `legacy_filenames` in your YML configuration, then run the `MigrateFileTask`. This will normalise 
the path of all existing assets.

#### Can I still choose legacy_filenames=true when starting new upgrades?

Technically yes, but you need to be aware of the tradeoffs. Once the regression has been fixed, we don’t see the need 
for people to choose this option any more.

SilverStripe 4.4, ignores the `legacy_filenames` in most situation. Enabling `legacy_filenames` on a fresh SilverStripe 
4.4 installation will have no affect.

#### How do I test that the fix has worked on my site?

Before applying the upgrade and migration script:
Find an existing published and draft file. Get the link by clicking on the preview in `admin/assets`.
It should link to `assets/[hash]/myfile.pdf`.

After applying the upgrade and migration task, you can test that it applied correctly.
Please perform these tests on a test or UAT environment, since your local environment might have different routing 
conditions.

 * Check that the file still routes correctly with the hash in place (should redirect)
 * Remove `[hash]/`, and check that it still routes correctly (should not redirect)
 
#### Will this patch redirect URLs for previous file versions?

Yes, it will attempt to find the most recent public "hash-less" URL
for this file and redirect to it.


## Changes to internal APIs

 - `PDOQuery::__construct()` now has a 2nd argument. If you have subclassed PDOQuery and overridden __construct() 
   you may see an E_STRICT error
 - The name of the directory where vendor module resources are exposed can now be configured by adding a `extra.resources-dir` key to your composer file. The new default in `silverstripe/installer` has been changed to `_resources` rather than `resources`. This allows you to use `resources` as a URL segment or a route.