only allow string keys for context values

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

packages/backend-common/api-report.md

@@ -152,7 +152,7 @@ export interface Context {
   readonly abortSignal: AbortSignal_2;
   readonly deadline: Date | undefined;
   use(...decorators: ContextDecorator[]): Context;
-  value<T = unknown>(key: string | symbol): T | undefined;
+  value<T = unknown>(key: string): T | undefined;
 }
 
 // @public
@@ -165,7 +165,7 @@ export class Contexts {
   static setTimeoutDuration(timeout: Duration): ContextDecorator;
   static setTimeoutMillis(timeout: number): ContextDecorator;
   static setValue(
-    key: string | symbol,
+    key: string,
     value: unknown | ((previous: unknown | undefined) => unknown),
   ): ContextDecorator;
 }

packages/backend-common/src/context/AbortContext.ts

@@ -127,7 +127,7 @@ export class AbortContext implements Context {
     readonly deadline: Date | undefined,
   ) {}
 
-  value<T = unknown>(key: string | symbol): T | undefined {
+  value<T = unknown>(key: string): T | undefined {
     return this.parent.value(key);
   }
 

packages/backend-common/src/context/Contexts.ts

@@ -99,7 +99,7 @@ export class Contexts {
    * @returns A decorator that can be passed to {@link Context.use}
    */
   static setValue(
-    key: string | symbol,
+    key: string,
     value: unknown | ((previous: unknown | undefined) => unknown),
   ): ContextDecorator {
     return ctx => {

packages/backend-common/src/context/RootContext.ts

@@ -24,7 +24,7 @@ export class RootContext implements Context {
   readonly abortSignal = new AbortController().signal;
   readonly deadline = undefined;
 
-  value<T = unknown>(_key: string | symbol): T | undefined {
+  value<T = unknown>(_key: string): T | undefined {
     return undefined;
   }
 

packages/backend-common/src/context/ValueContext.test.ts

@@ -18,31 +18,29 @@ import { Contexts } from './Contexts';
 import { RootContext } from './RootContext';
 import { ValueContext } from './ValueContext';
 
-const s = Symbol();
-
 describe('ValueContext', () => {
   it('returns its own values, or delegates to the parent', async () => {
     const root = new RootContext();
     const a = ValueContext.forConstantValue(root, 'a', 1);
-    const b = ValueContext.forConstantValue(a, s, 2);
+    const b = ValueContext.forConstantValue(a, 'x', 2);
     const c = ValueContext.forConstantValue(b, 'a', 3);
     const d = ValueContext.forConstantValue(c, 'b', 4);
 
     expect(a.value('a')).toBe(1);
     expect(a.value('b')).toBeUndefined();
-    expect(a.value(s)).toBeUndefined();
+    expect(a.value('x')).toBeUndefined();
 
     expect(b.value('a')).toBe(1);
     expect(b.value('b')).toBeUndefined();
-    expect(b.value(s)).toBe(2);
+    expect(b.value('x')).toBe(2);
 
     expect(c.value('a')).toBe(3);
     expect(c.value('b')).toBeUndefined();
-    expect(c.value(s)).toBe(2);
+    expect(c.value('x')).toBe(2);
 
     expect(d.value('a')).toBe(3);
     expect(d.value('b')).toBe(4);
-    expect(d.value(s)).toBe(2);
+    expect(d.value('x')).toBe(2);
   });
 
   it('can decorate', () => {

packages/backend-common/src/context/ValueContext.ts

@@ -22,17 +22,13 @@ import { Context, ContextDecorator } from './types';
  * parent.
  */
 export class ValueContext implements Context {
-  static forConstantValue(
-    ctx: Context,
-    key: string | symbol,
-    value: unknown,
-  ): Context {
+  static forConstantValue(ctx: Context, key: string, value: unknown): Context {
     return new ValueContext(ctx, key, value);
   }
 
   constructor(
     private readonly _parent: Context,
-    private readonly _key: string | symbol,
+    private readonly _key: string,
     private readonly _value: unknown,
   ) {}
 
@@ -44,7 +40,7 @@ export class ValueContext implements Context {
     return this._parent.deadline;
   }
 
-  value<T = unknown>(key: string | symbol): T | undefined {
+  value<T = unknown>(key: string): T | undefined {
     return key === this._key ? (this._value as T) : this._parent.value(key);
   }
 

packages/backend-common/src/context/types.ts

@@ -49,7 +49,7 @@ export interface Context {
    * @param key - The key of the value to get
    * @returns The associated value, or undefined if not set
    */
-  value<T = unknown>(key: string | symbol): T | undefined;
+  value<T = unknown>(key: string): T | undefined;
 
   /**
    * Decorates this context with one or more behaviors.