Support ViewEntity dependency configuration

[zaro]

Feature Description

Currently TypeORM doesn't support any way of specifying dependencies between views, which often leads to migrations being able to execute only after manual editing of the generated code.

The Problem

Suppose we have ViewA and ViewB. ViewB is using ViewA inside it's definition, so the normal order is to create first ViewA and then ViewB. Now if there is a change in ViewA, we can't execute it w/o first dropping ViewB, adjusting VIewA and then creating ViewB back. In typeorm if we edit only ViewA, the resulting migration will generate only changes for ViewA , and the migration will fail to execute because ViewB still holds a reference to ViewA and the DROP VIEW statement will fail. A workaround this will be to make also some trivial change to ViewB so it also ends up being updated in the migration. Unfortunately even this is not sufficient as the order in which these are generated is based on import order or something like this, so the DROP/CREATE statements often end up in the wrong order , e.g dropping ViewA before ViewB, and a manual edit of the migration file is needed.
With more views and dependencies the process can get quite cumbersome and error prone.

The Solution

Introduce new config for the VIewEntity decorator where we can explicitly list that a view is depending on another view and then generate the migration in the correct order based on this configuration.

Example

////////////////////////////////////////////////////////////
// viewA.ts
@ViewEntity({
    expression: `
      select * from tableA    
    `
})

export class ViewA{
//...
}
////////////////////////////////////////////////////////////
// viewB.ts

import {ViewA} from './viewA.ts';

@ViewEntity({
    expression: `
      select * from ViewA  ​ where column > 5
   `,
   dependsOn: [ViewA]
})
export class ViewB{
//...
}

Considered Alternatives

None that I could think of

Relevant Database Driver(s)

Not connected to specific drivers, affects all SQL databases that support views.

Are you willing to resolve this issue by submitting a Pull Request?

• ✅ Yes, I have the time, and I know how to start.
• ✖️ Yes, I have the time, but I don't know how to start. I would need guidance.
• ✖️ No, I don’t have the time, but I can support (using donations) development.
• ✖️ No, I don’t have the time and I’m okay to wait for the community / maintainers to resolve this issue.

[mwanago]

@zaro Can this issue be closed, since you've merged the PR?
Cool work! 👍

[zaro]

@mwanago Yes, thanks for reminding me.

[yanqic]

#8511 test