feat!: remove ctx transformer, add provider hooks (open-feature#148)

Add provider hooks, update ordering

BREAKING CHANGE: context transformer and related interfaces removed.

Signed-off-by: Todd Baert <[email protected]>

Signed-off-by: Todd Baert <[email protected]>

Author: toddbaert

src/client.ts

@@ -10,8 +10,8 @@ import {
   FlagValueType,
   Hook,
   HookContext,
+  Provider,
   ResolutionDetails,
-  TransformingProvider,
 } from './types';
 
 type OpenFeatureClientOptions = {
@@ -27,7 +27,7 @@ export class OpenFeatureClient implements Client {
   constructor(
     // we always want the client to use the current provider,
     // so pass a function to always access the currently registered one.
-    private readonly providerAccessor: () => TransformingProvider<unknown>,
+    private readonly providerAccessor: () => Provider,
     options: OpenFeatureClientOptions,
     context: EvaluationContext = {}
   ) {
@@ -148,7 +148,7 @@ export class OpenFeatureClient implements Client {
     resolver: (
       flagKey: string,
       defaultValue: T,
-      transformedContext: unknown,
+      context: EvaluationContext,
       options: FlagEvaluationOptions | undefined
     ) => Promise<ResolutionDetails<T>>,
     defaultValue: T,
@@ -158,13 +158,14 @@ export class OpenFeatureClient implements Client {
   ): Promise<EvaluationDetails<T>> {
     // merge global, client, and evaluation context
 
-    const allHooks = [...OpenFeature.hooks, ...this.hooks, ...(options.hooks || [])];
+    const allHooks = [...OpenFeature.hooks, ...this.hooks, ...(options.hooks || []), ...(this.provider.hooks || [])];
     const allHooksReversed = [...allHooks].reverse();
 
     // merge global and client contexts
-    const globalAndClientContext = {
+    const mergedContext = {
       ...OpenFeature.context,
       ...this.context,
+      ...invocationContext,
     };
 
     // this reference cannot change during the course of evaluation
@@ -175,26 +176,14 @@ export class OpenFeatureClient implements Client {
       flagValueType: flagType,
       clientMetadata: this.metadata,
       providerMetadata: OpenFeature.providerMetadata,
-      context: globalAndClientContext,
+      context: mergedContext,
     };
 
     try {
-      const mergedHookContext = await this.beforeHooks(allHooks, hookContext, options);
-
-      // merge context in order: global, client, hook, invocation
-      const mergedContext = {
-        ...mergedHookContext,
-        ...invocationContext,
-      };
-
-      // if a transformer is defined, run it to prepare the context
-      const transformedContext =
-        typeof this.provider.contextTransformer === 'function'
-          ? await this.provider.contextTransformer(mergedContext)
-          : mergedContext;
+      const frozenContext = await this.beforeHooks(allHooks, hookContext, options);
 
       // run the referenced resolver, binding the provider.
-      const resolution = await resolver.call(this.provider, flagKey, defaultValue, transformedContext, options);
+      const resolution = await resolver.call(this.provider, flagKey, defaultValue, frozenContext, options);
 
       const evaluationDetails = {
         ...resolution,

src/open-feature.ts

@@ -1,15 +1,6 @@
 import { OpenFeatureClient } from './client';
 import { NOOP_PROVIDER } from './no-op-provider';
-import {
-  Client,
-  EvaluationContext,
-  EvaluationLifeCycle,
-  FlagValue,
-  Hook,
-  NonTransformingProvider,
-  Provider,
-  TransformingProvider,
-} from './types';
+import { Client, EvaluationContext, EvaluationLifeCycle, FlagValue, Hook, Provider } from './types';
 
 // use a symbol as a key for the global singleton
 const GLOBAL_OPENFEATURE_API_KEY = Symbol.for('@openfeature/js.api');
@@ -36,7 +27,7 @@ class OpenFeatureAPI implements EvaluationLifeCycle {
   }
 
   getClient(name?: string, version?: string, context?: EvaluationContext): Client {
-    return new OpenFeatureClient(() => this._provider as TransformingProvider<unknown>, { name, version }, context);
+    return new OpenFeatureClient(() => this._provider, { name, version }, context);
   }
 
   get providerMetadata() {
@@ -51,7 +42,7 @@ class OpenFeatureAPI implements EvaluationLifeCycle {
     return this._hooks;
   }
 
-  setProvider(provider: TransformingProvider<unknown> | NonTransformingProvider) {
+  setProvider(provider: Provider) {
     this._provider = provider;
   }
 

src/types.ts

@@ -104,11 +104,12 @@ export interface Features {
 }
 
 /**
- * Function which transforms the EvaluationContext to a type useful for the provider.
+ * Interface that providers must implement to resolve flag values for their particular
+ * backend or vendor.
+ *
+ * Implementation for resolving all the required flag types must be defined.
  */
-export type ContextTransformer<T = unknown> = (context: EvaluationContext) => T;
-
-interface GenericProvider<T> {
+export interface Provider extends Pick<Partial<EvaluationLifeCycle>, 'hooks'> {
   readonly metadata: ProviderMetadata;
 
   /**
@@ -117,7 +118,7 @@ interface GenericProvider<T> {
   resolveBooleanEvaluation(
     flagKey: string,
     defaultValue: boolean,
-    transformedContext: T,
+    context: EvaluationContext,
     options: FlagEvaluationOptions | undefined
   ): Promise<ResolutionDetails<boolean>>;
 
@@ -127,7 +128,7 @@ interface GenericProvider<T> {
   resolveStringEvaluation(
     flagKey: string,
     defaultValue: string,
-    transformedContext: T,
+    context: EvaluationContext,
     options: FlagEvaluationOptions | undefined
   ): Promise<ResolutionDetails<string>>;
 
@@ -137,7 +138,7 @@ interface GenericProvider<T> {
   resolveNumberEvaluation(
     flagKey: string,
     defaultValue: number,
-    transformedContext: T,
+    context: EvaluationContext,
     options: FlagEvaluationOptions | undefined
   ): Promise<ResolutionDetails<number>>;
 
@@ -147,40 +148,17 @@ interface GenericProvider<T> {
   resolveObjectEvaluation<U extends object>(
     flagKey: string,
     defaultValue: U,
-    transformedContext: T,
+    context: EvaluationContext,
     options: FlagEvaluationOptions | undefined
   ): Promise<ResolutionDetails<U>>;
 }
 
-export type NonTransformingProvider = GenericProvider<EvaluationContext>;
-
-export interface TransformingProvider<T> extends GenericProvider<T> {
-  contextTransformer: ContextTransformer<Promise<T> | T> | undefined;
-}
-
-/**
- * Interface that providers must implement to resolve flag values for their particular
- * backend or vendor.
- *
- * Implementation for resolving all the required flag types must be defined.
- *
- * Additionally, a ContextTransformer function that transforms the OpenFeature context to the requisite user/context/attribute representation (typeof T)
- * may also be implemented. This function will run immediately before the flag value resolver functions, appropriately transforming the context.
- */
-export type Provider<T extends EvaluationContext | unknown = EvaluationContext> = T extends EvaluationContext
-  ? NonTransformingProvider
-  : TransformingProvider<T>;
-
 export interface EvaluationLifeCycle {
   addHooks(...hooks: Hook[]): void;
   get hooks(): Hook[];
   clearHooks(): void;
 }
 
-export interface ProviderOptions<T = unknown> {
-  contextTransformer?: ContextTransformer<T>;
-}
-
 export enum StandardResolutionReasons {
   /**
    * Indicates that the feature flag is targeting
@@ -204,20 +182,20 @@ export enum StandardResolutionReasons {
    * similar functions in the Client   */
   DEFAULT = 'DEFAULT',
   /**
-   * Indicates that the feature flag evaluated to a 
+   * Indicates that the feature flag evaluated to a
    * static value, for example, the default value for the flag
-   * 
+   *
    * Note: Typically means that no dynamic evaluation has been
    * executed for the feature flag
    */
-   STATIC = 'STATIC',
+  STATIC = 'STATIC',
   /**
    * Indicates an unknown issue occurred during evaluation
    */
   UNKNOWN = 'UNKNOWN',
   /**
    * Indicates that an error occurred during evaluation
-   * 
+   *
    * Note: The `errorCode`-field contains the details of this error
    */
   ERROR = 'ERROR',