EntitySchema with indices results in duplicate migration file entries

[dgobaud]

Issue type:
[X] bug report

Database system/driver:

[X] postgres

TypeORM version:

[X] 0.2.18 (or put your version here)

Below schema results in migration generation with the index create/drop calls happening 3 times. We fixed it by adding below visited array to filterIndices in typeorm/metadata-args/MetadataArgsStorage.js

Problem seems to be the metadata builder for some reasons loads indices three times (can't figure out where this is happening exactly).

seems related to #3280 and #4577

import {MigrationInterface, QueryRunner} from "typeorm";

export class test1573371622105 implements MigrationInterface {

    public async up(queryRunner: QueryRunner): Promise<any> {
        await queryRunner.query(`CREATE TABLE "public"."authenticators" ("id" uuid NOT NULL DEFAULT uuid_generate_v4(), "createdAt" TIMESTAMP NOT NULL DEFAULT now(), "updatedAt" TIMESTAMP NOT NULL DEFAULT now(), "code" character varying, CONSTRAINT "PK_ca66aa0ff269b0314c053ba20a2" PRIMARY KEY ("id"))`);
        await queryRunner.query(`CREATE UNIQUE INDEX "IDX_b301987c9252892c34fdface66" ON "public"."authenticators" ("code") `);
        await queryRunner.query(`CREATE UNIQUE INDEX "IDX_b301987c9252892c34fdface66" ON "public"."authenticators" ("code") `);
        await queryRunner.query(`CREATE UNIQUE INDEX "IDX_b301987c9252892c34fdface66" ON "public"."authenticators" ("code") `);
    }

    public async down(queryRunner: QueryRunner): Promise<any> {
        await queryRunner.query(`DROP INDEX "public"."IDX_b301987c9252892c34fdface66"`);
        await queryRunner.query(`DROP INDEX "public"."IDX_b301987c9252892c34fdface66"`);
        await queryRunner.query(`DROP INDEX "public"."IDX_b301987c9252892c34fdface66"`);
        await queryRunner.query(`DROP TABLE "public"."authenticators"`);
    }

}

    MetadataArgsStorage.prototype.filterIndices = function (target) {
        var visited = []
        // todo: implement parent-entity overrides?
        return this.indices.filter(function (index) {
            const indexKey = index.target + index.name
            if (visited.indexOf(indexKey) >= 0 ) {
                return false
            }
            visited.push(indexKey)
            return target instanceof Array ? target.indexOf(index.target) !== -1 : index.target === target;
        });
    };

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const typeorm_1 = require("typeorm");
exports.authenticator = new typeorm_1.EntitySchema({
    name: 'authenticators',
    columns: {
        id: {
            type: 'uuid',
            primary: true,
            generated: 'uuid',
            nullable: false
        },
        createdAt: {
            type: 'timestamp',
            createDate: true
        },
        updatedAt: {
            type: 'timestamp',
            updateDate: true
        },
        code: {
            type: String,
            nullable: true
        }
    },
    indices: [
        {
            columns: ['code'],
            unique: true
        }
    ]
});