Implement em::findOneOrFail

[kgoncharov]

Is your feature request related to a problem? Please describe.
Sometimes it's very convenient to have a short method that will fail-fast if nothing was found.

Describe the solution you'd like
em::findOrFail that return Promise<T> or throw exception if entity wasn't found.

[B4nan]

Agreed, I am usually defining this method in custom base repository, but sure we can have it integrated as well. Personally I am using custom NotFoundException that is later on catched in main request handler and handled as 404 response. I guess we could allow configuring a callback where users could provide their own exception and possibly error message based on what was not found.

Maybe better name would be findOneOrFail? or even findOneOrThrow?

[kgoncharov]

I supposed that this method would be used only for situations, where the entity should be in database, and if there is no entity server should return InternalServerException at the end, to show that there's some inconsistency in database.
For this purposes findOneOrFail name would be the best.
On the other hand there could be two methods:
findOneOrThrow - for custom handling on what exception we're going to throw (NotFoundException, etc)
findOneOrFail - for fatal and critical errors that will return some critical custom exception that could be propagated to InternalServerException
@B4nan wdyt?

[B4nan]

I think that could cause a lot of confusion, I would like to have only one method for this.

Btw for your InternalServerException use case, how are you handling 404s? I guess manually, right? Then with my proposal you would just set up the callback to produce InternalServerException and keep handling the 404 manually (either via try/catch or via truthy checks). Or as I already said, you can always define your own methods in base repository (you can set your own base repository for all entities in ORM's configuration).

[kgoncharov]

Yep, manually.
Anyway, just findOneOrFail with capability to set custom exception to throw would be great.

[vimmerru]

I would like

cons used = await findOneOrFail(
    id,
    () => InternalServerError(`No expected user in db: ${id}`));

[B4nan]

findOne already has more complex interface:

async findOne<T extends IEntityType<T>>(entityName: EntityName<T>, where: FilterQuery<T> | IPrimaryKey, populate?: string[] | FindOneOptions, orderBy?: QueryOrderMap): Promise<T | null> {

But yes, I like the idea to allow overriding the default exception handler via it's parameters, probably via FindOneOptions (probably FindOneOrFailOptions that will extend that).

[B4nan]

Available for testing in 3.0.0-alpha.9. Closing as resolved.

Docs: 0d57b7b#diff-474106f26d234ca3b44599c73da3d296R112