This is called for each query before it is executed. You can modify the query by transforming its OperationNode tree provided in args.node and returning the transformed tree. You'd usually want to use an OperationNodeTransformer for this.
If you need to pass some query-related data between this method and transformResult you
can use a WeakMap with args.queryId as the key:
import type {
KyselyPlugin,
QueryResult,
RootOperationNode,
UnknownRow
} from 'kysely'
interface MyData {
// ...
}
const data = new WeakMap<any, MyData>()
const plugin = {
transformQuery(args: PluginTransformQueryArgs): RootOperationNode {
const something: MyData = {}
// ...
data.set(args.queryId, something)
// ...
return args.node
},
async transformResult(args: PluginTransformResultArgs): Promise<QueryResult<UnknownRow>> {
// ...
const something = data.get(args.queryId)
// ...
return args.result
}
} satisfies KyselyPlugin
You should use a WeakMap instead of a Map or some other strong references because transformQuery
is not always matched by a call to transformResult which would leave orphaned items in the map
and cause a memory leak.
This method is called for each query after it has been executed. The result of the query can be accessed through args.result. You can modify the result and return the modifier result.
Plugin that handles NULL comparisons to prevent common SQL mistakes.
In SQL, comparing values with NULL using standard comparison operators (=, !=, <>) always yields NULL, which is usually not what developers expect. The correct way to compare with NULL is using IS NULL and IS NOT NULL.
When working with nullable variables (e.g. string | null), you need to be careful to manually handle these cases with conditional WHERE clauses. This plugins automatically applies the correct operator based on the value, allowing you to simply write
query.where('name', '=', name).The plugin transforms the following operators when comparing with NULL:
=becomesIS!=becomesIS NOT<>becomesIS NOT