Dedup exact same selectors while keep original precedence

src/AzureAppConfigurationImpl.ts

@@ -6,11 +6,11 @@ import { AzureAppConfiguration } from "./AzureAppConfiguration";
 import { AzureAppConfigurationOptions } from "./AzureAppConfigurationOptions";
 import { IKeyValueAdapter } from "./IKeyValueAdapter";
 import { JsonKeyValueAdapter } from "./JsonKeyValueAdapter";
-import { KeyFilter } from "./KeyFilter";
-import { LabelFilter } from "./LabelFilter";
+import { KeyFilter, LabelFilter } from "./types";
 import { AzureKeyVaultKeyValueAdapter } from "./keyvault/AzureKeyVaultKeyValueAdapter";
 import { CorrelationContextHeaderName } from "./requestTracing/constants";
 import { createCorrelationContextHeader, requestTracingEnabled } from "./requestTracing/utils";
+import { SettingSelector } from "./types";
 
 export class AzureAppConfigurationImpl extends Map<string, unknown> implements AzureAppConfiguration {
     private adapters: IKeyValueAdapter[] = [];
@@ -109,12 +109,23 @@ export class AzureAppConfigurationImpl extends Map<string, unknown> implements A
     }
 }
 
-function getValidSelectors(selectors?: { keyFilter: string, labelFilter?: string }[]) {
+function getValidSelectors(selectors?: SettingSelector[]) {
     if (!selectors || selectors.length === 0) {
         // Default selector: key: *, label: \0
         return [{ keyFilter: KeyFilter.Any, labelFilter: LabelFilter.Null }];
     }
-    return selectors.map(selectorCandidate => {
+
+    // below code dedupes selectors by keyFilter and labelFilter, the latter selector wins
+    const dedupedSelectors: SettingSelector[] = [];
+    for (const selector of selectors) {
+        const existingSelectorIndex = dedupedSelectors.findIndex(s => s.keyFilter === selector.keyFilter && s.labelFilter === selector.labelFilter);
+        if (existingSelectorIndex >= 0) {
+            dedupedSelectors.splice(existingSelectorIndex, 1);
+        }
+        dedupedSelectors.push(selector);
+    }
+
+    return dedupedSelectors.map(selectorCandidate => {
         const selector = { ...selectorCandidate };
         if (!selector.keyFilter) {
             throw new Error("Key filter cannot be null or empty.");

src/AzureAppConfigurationOptions.ts

@@ -3,31 +3,17 @@
 
 import { AppConfigurationClientOptions } from "@azure/app-configuration";
 import { AzureAppConfigurationKeyVaultOptions } from "./keyvault/AzureAppConfigurationKeyVaultOptions";
+import { SettingSelector } from "./types";
 
 export const MaxRetries = 2;
 export const MaxRetryDelayInMs = 60000;
 
 export interface AzureAppConfigurationOptions {
     /**
-     * Specify what key-values to include in the configuration provider.  include multiple sets of key-values
-     *
-     * @property keyFilter:
-     * The key filter to apply when querying Azure App Configuration for key-values.
-     * An asterisk `*` can be added to the end to return all key-values whose key begins with the key filter.
-     * e.g. key filter `abc*` returns all key-values whose key starts with `abc`.
-     * A comma `,` can be used to select multiple key-values. Comma separated filters must exactly match a key to select it.
-     * Using asterisk to select key-values that begin with a key filter while simultaneously using comma separated key filters is not supported.
-     * E.g. the key filter `abc*,def` is not supported. The key filters `abc*` and `abc,def` are supported.
-     * For all other cases the characters: asterisk `*`, comma `,`, and backslash `\` are reserved. Reserved characters must be escaped using a backslash (\).
-     * e.g. the key filter `a\\b\,\*c*` returns all key-values whose key starts with `a\b,*c`.
-     *
-     * @property labelFilter:
-     * The label filter to apply when querying Azure App Configuration for key-values.
-     * By default, the "null label" will be used, matching key-values without a label.
-     * The characters asterisk `*` and comma `,` are not supported.
-     * Backslash `\` character is reserved and must be escaped using another backslash `\`.
+     * Specify what key-values to include in the configuration provider.
+     * If no selectors are specified then all key-values with no label will be included.
      */
-    selectors?: { keyFilter: string, labelFilter?: string }[];
+    selectors?: SettingSelector[];
 
     /**
      * Specifies prefixes to be trimmed from the keys of all key-values retrieved from Azure App Configuration.

src/index.ts

@@ -3,5 +3,4 @@
 
 export { load } from "./load";
 export { AzureAppConfiguration } from "./AzureAppConfiguration";
-export { KeyFilter } from "./KeyFilter";
-export { LabelFilter } from "./LabelFilter";
+export { KeyFilter, LabelFilter } from "./types";

src/types.ts

@@ -0,0 +1,44 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+/**
+ * SettingSelector is used to select key-values from Azure App Configuration.
+ * It is used to filter key-values based on keys and labels.
+ * 
+ * @property keyFilter:
+ * The key filter to apply when querying Azure App Configuration for key-values.
+ * An asterisk `*` can be added to the end to return all key-values whose key begins with the key filter.
+ * e.g. key filter `abc*` returns all key-values whose key starts with `abc`.
+ * A comma `,` can be used to select multiple key-values. Comma separated filters must exactly match a key to select it.
+ * Using asterisk to select key-values that begin with a key filter while simultaneously using comma separated key filters is not supported.
+ * E.g. the key filter `abc*,def` is not supported. The key filters `abc*` and `abc,def` are supported.
+ * For all other cases the characters: asterisk `*`, comma `,`, and backslash `\` are reserved. Reserved characters must be escaped using a backslash (\).
+ * e.g. the key filter `a\\b\,\*c*` returns all key-values whose key starts with `a\b,*c`.
+ *
+ * @property labelFilter:
+ * The label filter to apply when querying Azure App Configuration for key-values.
+ * By default, the "null label" will be used, matching key-values without a label.
+ * The characters asterisk `*` and comma `,` are not supported.
+ * Backslash `\` character is reserved and must be escaped using another backslash `\`.
+ */
+export type SettingSelector = { keyFilter: string, labelFilter?: string };
+
+/**
+ * KeyFilter is used to filter key-values based on keys.
+ *
+ * @property Any:
+ * Matches all key-values.
+ */
+export enum KeyFilter {
+    Any = "*"
+}
+
+/**
+ * LabelFilter is used to filter key-values based on labels.
+ *
+ * @property Null:
+ * Matches key-values without a label.
+ */
+export enum LabelFilter {
+    Null = "\0"
+}

test/load.test.ts

@@ -151,4 +151,24 @@ describe("load", function () {
         expect(settings.has("TestKey")).eq(true);
         expect(settings.get("TestKey")).eq("TestValueForProd");
     });
-})
+
+    it("should dedup exact same selectors but keeping the precedence", async () => {
+        const connectionString = createMockedConnectionString();
+        const settings = await load(connectionString, {
+            selectors: [{
+                keyFilter: "Test*",
+                labelFilter: "Prod"
+            }, {
+                keyFilter: "Test*",
+                labelFilter: "Test"
+            }, {
+                keyFilter: "Test*",
+                labelFilter: "Prod"
+            }]
+        });
+        expect(settings).not.undefined;
+        expect(settings.has("TestKey")).eq(true);
+        expect(settings.get("TestKey")).eq("TestValueForProd");
+    });
+
+});