Unified API to execute ECSQL query on an iModel, working on both frontend and backend?

[AlexandreWalensa]

Hi, I am writing a utility package that needs to execute ECSQL queries on an iModel.
From what I see, executing ECSQL queries has a dedicated API for backend (using class IModelDB) and another API for frontend (using class IModelConnection).
Ideally, I would like my utility to be "frontend/backend - agnostic", ie. I would write the same code that would accept any instance of class IModel (concrete class could be IModelDB or IModelConnection).
Is there an existing unified API to execute ECSQL query on an iModel, working on both frontend and backend?

[grigasp]

Hi @AlexandreWalensa. The @iTwin/itwinjs-core-presentation team had the same issue, here's what we came up with:

• The signature of createQueryReader function on IModelDb and IModelConnection is exactly the same, so you can create a type that defines an object with this function, and then both IModelDb and IModelConnection will meet the type's requirement. Here's how we typed it: https://github.com/iTwin/presentation/blob/6f3464afefe54aeccbe72e51084566f88abac1c5/packages/core-interop/src/core-interop/QueryExecutor.ts#L26.

• Going a step further (which you may not need), we wanted to avoid a dependency on @itwin/core-common, so we created our own type for a query reader and mapped core's reader to ours - https://github.com/iTwin/presentation/blob/6f3464afefe54aeccbe72e51084566f88abac1c5/packages/core-interop/src/core-interop/QueryExecutor.ts#L48.

[grigasp]

Based on the first point, though, I would raise a question if the createQueryReader can't be defined as an abstract function on IModel in @itwin/core-common. @aruniverse

[AlexandreWalensa]

Thanks Grigas for your quick reply.