config.datasources[0].provider from GetConfig needs to be a string and not a string[]

[Jolg42]

Problem

const config = await getConfig({
	datamodel: schema,
})

// this `provider` value was a string before 2.22.0 but is now an array of string
config.datasources[0].provider

This is the related commit that introduced the regression:
prisma/prisma-engines@b096a80

In this commit it looks like we removed the array from the datasource but added it to the serialization.

Rust Type found in https://github.com/prisma/prisma-engines/blob/master/libs/datamodel/core/src/configuration/datasource.rs#L12-L13

    /// The provider string
    pub provider: String,

the tests also show it’s currently an array of strings with only one string https://github.com/prisma/prisma-engines/blob/master/libs/datamodel/core/tests/config/datasources.rs#L16

Suggestion

I think it should be a string and not an array returned here by the Rust code.

I could monkey patch in the CLI but it seems wrong because we have a datasource[] array and each datasource can only have one provider.
It looks like some legacy from the multi provider array feature deprecated a while ago.

Internal Slack Thread here

[thebiglabasky]

We'll for now research places where this fix on getConfig would have an impact to ensure we don't break unexpectedly shortly before releasing.
Next step is to share the outcome of the research here before deciding how to fix this.
People to speak to: @madebysid (Studio), @millsp and/or @williamluke4

[sdnts]

Studio doesn't use getConfig directly anymore, so we're good there. If the getGenerators function behaves the same as before, Studio will not need any changes.

[Jolg42]

Found these lines using it, we can easily fix them after the engine fix:

• prisma/packages/sdk/src/engine-commands/getConfig.ts

  Line 56 in 7a6ad37

  data.datasources?.[0]?.provider?.[0] === 'sqlite' &&

• prisma/packages/sdk/src/getGenerators.ts

  Lines 154 to 162 in 7a6ad37

  	if (config.datasources.some((d) => d.provider.includes('mongodb'))) {
  	throw new Error(missingModelMessageMongoDB)
  	}
  	throw new Error(missingModelMessage)
  	}
  	if (
  	config.datasources.some((d) => d.provider.includes('mongodb')) &&

• prisma/packages/migrate/src/utils/ensureDatabaseExists.ts

  Line 110 in 7a6ad37

  if (activeDatasource.provider[0] === 'mongodb') {

• prisma/packages/migrate/src/utils/ensureDatabaseExists.ts

  Line 76 in 7a6ad37

  if (activeDatasource.provider[0] === 'mongodb') {

Tried the hacky patch on TS side and can confirm it works.

[pimeys]

Reopening, so @Jolg42 can close it if nothing breaks in the clients.

[Jolg42]

Closing, small changes were made in #8556 which then made it through our dev pipeline in 2.29.0-dev.24

Thanks! 💚