refactor: simplify design of metadata hook

coder · Parkreiner · May 3, 2024 · May 2, 2024 · May 2, 2024 · May 2, 2024
commit e072f7ad40a3814e6496df75b24b5096659046c6
@@ -56,12 +56,13 @@ export function cachedQuery<
   >,
 ): FormattedQueryOptionsResult<TQueryFnData, TError, TData, TQueryKey> {
   const { metadata, ...delegatedOptions } = options;
-  const metadataIsAvailable = metadata.status === "loaded";
-
   const newOptions = {
     ...delegatedOptions,
-    ...(metadataIsAvailable ? disabledFetchOptions : {}),
-    initialData: metadataIsAvailable ? metadata.value : undefined,
+    initialData: metadata.available ? metadata.value : undefined,
+
+    // Make sure the disabled options are always serialized last, so that no
+    // one using this function can accidentally override the values
+    ...(metadata.available ? disabledFetchOptions : {}),
   };
 
   return newOptions as FormattedQueryOptionsResult<

@@ -34,9 +34,14 @@ export type MetadataState<T extends MetadataValue> = Readonly<{
   // undefined chosen to signify missing value because unlike null, it isn't a
   // valid JSON-serializable value. It's impossible to be returned by the API
   value: T | undefined;
-  status: "missing" | "loaded" | "deleted";
+  available: boolean;
 }>;
 
+const unavailableState = {
+  value: undefined,
+  available: false,
+} as const satisfies MetadataState<MetadataValue>;
+
 export type RuntimeHtmlMetadata = Readonly<{
   [Key in MetadataKey]: MetadataState<AvailableMetadata[Key]>;
 }>;
@@ -78,7 +83,7 @@ export class MetadataManager implements MetadataManagerApi {
       entitlements: this.registerValue<Entitlements>("entitlements"),
       experiments: this.registerValue<Experiments>("experiments"),
       "build-info": this.registerValue<BuildInfoResponse>("build-info"),
-      regions: this.registerRegionValue("region"),
+      regions: this.registerRegionValue(),
     };
   }
 
@@ -99,7 +104,7 @@ export class MetadataManager implements MetadataManagerApi {
    * can be tightened up even further (e.g., adding a type constraint to
    * parseJson)
    */
-  private registerRegionValue(key: "region"): MetadataState<readonly Region[]> {
+  private registerRegionValue(): MetadataState<readonly Region[]> {
     type RegionResponse =
       | readonly Region[]
       | Readonly<{
@@ -110,13 +115,14 @@ export class MetadataManager implements MetadataManagerApi {
 
     let newEntry: MetadataState<readonly Region[]>;
     if (!node || value === undefined) {
-      newEntry = { value: undefined, status: "missing" };
+      newEntry = unavailableState;
     } else if ("regions" in value) {
-      newEntry = { value: value.regions, status: "loaded" };
+      newEntry = { value: value.regions, available: true };
     } else {
-      newEntry = { value, status: "loaded" };
+      newEntry = { value, available: true };
     }
 
+    const key = "regions" satisfies MetadataKey;
     this.trackedMetadataNodes.set(key, node);
     return newEntry;
   }
@@ -128,9 +134,9 @@ export class MetadataManager implements MetadataManagerApi {
 
     let newEntry: MetadataState<T>;
     if (!node || value === undefined) {
-      newEntry = { value: undefined, status: "missing" };
+      newEntry = unavailableState;
     } else {
-      newEntry = { value, status: "loaded" };
+      newEntry = { value, available: true };
     }
 
     this.trackedMetadataNodes.set(key, node);
@@ -177,7 +183,7 @@ export class MetadataManager implements MetadataManagerApi {
 
   clearMetadataByKey = (key: MetadataKey): void => {
     const metadataValue = this.metadata[key];
-    if (metadataValue.status === "missing") {
+    if (!metadataValue.available) {
       return;
     }
 
@@ -188,14 +194,7 @@ export class MetadataManager implements MetadataManagerApi {
     // the value after it's supposed to have been made unavailable
     metadataNode?.remove();
 
-    type NewState = MetadataState<NonNullable<typeof metadataValue.value>>;
-    const newState: NewState = {
-      ...metadataValue,
-      value: undefined,
-      status: "deleted",
-    };
-
-    this.metadata = { ...this.metadata, [key]: newState };
+    this.metadata = { ...this.metadata, [key]: unavailableState };
     this.notifySubscriptionsOfStateChange();
   };
 }