feat: add comment param to FindOptions (#8545)

* add comment option to FindOptions.

Allows users to pass in comments for queries issued through the entity manager
like they are for the query builder.

* use promisify for node 12

* fix comment

src/find-options/FindOneOptions.ts

@@ -8,6 +8,13 @@ import {FindConditions} from "./FindConditions";
  */
 export interface FindOneOptions<Entity = any> {
 
+    /**
+     * Adds a comment with the supplied string in the generated query.  This is
+     * helpful for debugging purposes, such as finding a specific query in the
+     * database server's logs, or for categorization using an APM product.
+     */
+    comment?: string;
+
     /**
      * Specifies what columns should be retrieved.
      */

src/find-options/FindOptionsUtils.ts

@@ -32,6 +32,7 @@ export class FindOptionsUtils {
                 possibleOptions.cache instanceof Object ||
                 typeof possibleOptions.cache === "boolean" ||
                 typeof possibleOptions.cache === "number" ||
+                typeof possibleOptions.comment === "string" ||
                 possibleOptions.lock instanceof Object ||
                 possibleOptions.loadRelationIds instanceof Object ||
                 typeof possibleOptions.loadRelationIds === "boolean" ||
@@ -97,6 +98,10 @@ export class FindOptionsUtils {
         const metadata = qb.expressionMap.mainAlias!.metadata;
 
         // apply all options from FindOptions
+        if (options.comment) {
+            qb.comment(options.comment);
+        }
+
         if (options.withDeleted) {
             qb.withDeleted();
         }

test/functional/repository/find-options/repository-find-options.ts

@@ -7,6 +7,9 @@ import {Category} from "./entity/Category";
 import {Post} from "./entity/Post";
 import {Photo} from "./entity/Photo";
 import sinon from "sinon";
+import {FileLogger} from "../../../../src";
+import {promisify} from "util";
+import {readFile, unlink} from "fs";
 
 describe("repository > find options", () => {
 
@@ -192,6 +195,38 @@ describe("repository > find options", () => {
 
 });
 
+describe("repository > find options > comment", () => {
+    let connections: Connection[];
+    const logPath = "find_comment_test.log";
+
+    before(async () => {
+        // TODO: would be nice to be able to do this in memory with some kind of
+        // test logger that buffers messages.
+        const logger = new FileLogger(["query"], { logPath });
+        connections = await createTestingConnections({
+            entities: [__dirname + "/entity/*{.js,.ts}"],
+            createLogger: () => logger,
+        });
+    });
+    beforeEach(() => reloadTestingDatabases(connections));
+    after(async () => {
+        closeTestingConnections(connections);
+        await promisify(unlink)(logPath);
+    });
+
+    it("repository should insert comment", () => Promise.all(connections.map(async connection => {
+        await connection.getRepository(User)
+            .find({comment: "This is a query comment."});
+
+        const logs = await promisify(readFile)(logPath);
+        const lines = logs.toString().split("\n");
+        const lastLine = lines[lines.length - 2]; // last line is blank after newline
+        // remove timestamp and prefix
+        const sql = lastLine.replace(/^.*\[QUERY\]\: /, "");
+        expect(sql).to.match(/^\/\* This is a query comment. \*\//);
+    })));
+});
+
 
 describe("repository > find options > cache", () => {
     let connections: Connection[];