Commit With Frontend and Backend in MERN

backend/node_modules/mongodb/src/read_concern.ts

@@ -0,0 +1,88 @@
+import type { Document } from './bson';
+
+/** @public */
+export const ReadConcernLevel = Object.freeze({
+  local: 'local',
+  majority: 'majority',
+  linearizable: 'linearizable',
+  available: 'available',
+  snapshot: 'snapshot'
+} as const);
+
+/** @public */
+export type ReadConcernLevel = (typeof ReadConcernLevel)[keyof typeof ReadConcernLevel];
+
+/** @public */
+export type ReadConcernLike = ReadConcern | { level: ReadConcernLevel } | ReadConcernLevel;
+
+/**
+ * The MongoDB ReadConcern, which allows for control of the consistency and isolation properties
+ * of the data read from replica sets and replica set shards.
+ * @public
+ *
+ * @see https://www.mongodb.com/docs/manual/reference/read-concern/index.html
+ */
+export class ReadConcern {
+  level: ReadConcernLevel | string;
+
+  /** Constructs a ReadConcern from the read concern level.*/
+  constructor(level: ReadConcernLevel) {
+    /**
+     * A spec test exists that allows level to be any string.
+     * "invalid readConcern with out stage"
+     * @see ./test/spec/crud/v2/aggregate-out-readConcern.json
+     * @see https://github.com/mongodb/specifications/blob/master/source/read-write-concern/read-write-concern.md#unknown-levels-and-additional-options-for-string-based-readconcerns
+     */
+    this.level = ReadConcernLevel[level] ?? level;
+  }
+
+  /**
+   * Construct a ReadConcern given an options object.
+   *
+   * @param options - The options object from which to extract the write concern.
+   */
+  static fromOptions(options?: {
+    readConcern?: ReadConcernLike;
+    level?: ReadConcernLevel;
+  }): ReadConcern | undefined {
+    if (options == null) {
+      return;
+    }
+
+    if (options.readConcern) {
+      const { readConcern } = options;
+      if (readConcern instanceof ReadConcern) {
+        return readConcern;
+      } else if (typeof readConcern === 'string') {
+        return new ReadConcern(readConcern);
+      } else if ('level' in readConcern && readConcern.level) {
+        return new ReadConcern(readConcern.level);
+      }
+    }
+
+    if (options.level) {
+      return new ReadConcern(options.level);
+    }
+    return;
+  }
+
+  static get MAJORITY(): 'majority' {
+    return ReadConcernLevel.majority;
+  }
+
+  static get AVAILABLE(): 'available' {
+    return ReadConcernLevel.available;
+  }
+
+  static get LINEARIZABLE(): 'linearizable' {
+    return ReadConcernLevel.linearizable;
+  }
+
+  static get SNAPSHOT(): 'snapshot' {
+    return ReadConcernLevel.snapshot;
+  }
+
+  toJSON(): Document {
+    return { level: this.level };
+  }
+}