`const` to `function` manager providers

TL;DR

Individual metadata managers const-based providers like OPEN_GRAPH_DESCRIPTION_METADATA_PROVIDER weren't tree shakeable by design . So they are replaced by function-based provider APIs. Like provideOpenGraphDescription

Update from 1.0.0-beta.34 to 1.0.0-beta.35 using ng update to replace old ones with new ones automatically for your project. See migration for more info about running automatic migrations or migrating manually.

Summary

Key	Value
Category of change	👎 Deprecation
Automatic migration schematics	✅ Yes. Via `ng update`
Introduced in version	`1.0.0-beta.35`

Description

Issue

🎟️ Detailed GitHub issue

The library allows to select individual metadata managers to use. For instance, just Open Graph title and description. This way you can use only the code you need, hence reducing your app's bundle size. Take a look at the custom metadata providers selection guide for more information.

Until 1.0.0-beta.35, individual metadata manager providers were consts that you could add to your providers to use them. With this naming convention:

OPEN_GRAPH_TITLE_METADATA_PROVIDER
STANDARD_TITLE_METADATA_PROVIDER
TWITTER_CARD_TITLE_METADATA_PROVIDER

However, the way these tokens are created means they aren't tree-shakeable (see GitHub issue for more details about why). Therefore, defeating its purpose of reducing the bundle size by just using the ones you need. All providers from a built-in metadata module would be included in the bundle size even if just one is used.

Options

If using pure annotations , const-based providers can be tree-shaken. But it's easy to forget to add them hence resulting in non-tree shakeable providers. Some tests could be added to enforce that, but it's more infra to maintain.

An alternative is to use functions instead of consts for individual metadata manager providers. Functions are tree-shaken by default if unused. And they provide flexibility to customize the behaviour of a metadata manager provider by adding arguments to it. So allows extensibility in the long run. The trade-off is some few extra bytes¹.

Changes

New function-based individual metadata manager providers use this naming convention:

provideOpenGraphTitle()
provideStandardTitle()
provideTwitterCardTitle()

The only exception is JSON_LD_METADATA_PROVIDER. Instead of a new function-based alternative, it is replaced by provideNgxMetaJsonLd. The JSON-LD module provider API. Given they actually do the same (indeed the latter calls the former under the hood). So no need to maintain two functions with same purpose.

Migration

In order to migrate from old const-based individual metadata manager providers into new, function-based individual metadata manager providers, you can:

Automatic

Use the automatic migration schematic by upgrading to that version with ng update command:

ng update @davidlj95/ngx-meta@latest

The schematic will look for old managers and replace them by new ones. It will fix imports too. If you have already upgraded, you can also run:

ng update @davidlj95/ngx-meta \
  --from=1.0.0-beta.35 \
  --migrate-only
# or also
ng update @davidlj95/ngx-meta \
  --name=const-to-function-manager-providers

Manual

Look for const-based individual metadata manager providers in your project and replace them with the new function-based providers. They are imported from the same entrypoint. They can be identified by their suffix: _METADATA_PROVIDER.

Some examples:

Old usage	New usage
`OPEN_GRAPH_TITLE_METADATA_PROVIDER`	`provideOpenGraphTitle`
`STANDARD_TITLE_METADATA_PROVIDER`	`provideStandardTitle`
`TWITTER_CARD_TITLE_METADATA_PROVIDER`	`provideTwitterCardTitle`
`JSON_LD_METADATA_PROVIDER`	`provideNgxMetaJsonLd`

The only change that doesn't follow the naming pattern is JSON_LD_METADATA_PROVIDER for the reasons stated in the changes section.

You can find a full list in the schematics testing support file

Finally, the custom metadata providers selection guide has been updated with new usages. But you can check an older version if you need to.

See the PR introducing changes for details about the extra bundle size increase. ↩

const to function manager providers