/
Transformer.ts
47 lines (39 loc) · 1.68 KB
/
Transformer.ts
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import { ExecutionRequest, ExecutionResult } from '@graphql-tools/utils';
import { DelegationContext, DelegationBinding, Transform } from './types';
import { defaultDelegationBinding } from './delegationBindings';
interface Transformation {
transform: Transform;
context: Record<string, any>;
}
export class Transformer<TContext = Record<string, any>> {
private transformations: Array<Transformation> = [];
private delegationContext: DelegationContext<any>;
constructor(context: DelegationContext<TContext>, binding: DelegationBinding<TContext> = defaultDelegationBinding) {
this.delegationContext = context;
const delegationTransforms: Array<Transform> = binding(this.delegationContext);
for (const transform of delegationTransforms) {
this.addTransform(transform, {});
}
}
private addTransform(transform: Transform, context = {}) {
this.transformations.push({ transform, context });
}
public transformRequest(originalRequest: ExecutionRequest) {
return this.transformations.reduce(
(request: ExecutionRequest, transformation: Transformation) =>
transformation.transform.transformRequest != null
? transformation.transform.transformRequest(request, this.delegationContext, transformation.context)
: request,
originalRequest
);
}
public transformResult(originalResult: ExecutionResult) {
return this.transformations.reduceRight(
(result: ExecutionResult, transformation: Transformation) =>
transformation.transform.transformResult != null
? transformation.transform.transformResult(result, this.delegationContext, transformation.context)
: result,
originalResult
);
}
}