Question

我的应用没有成功部署到Heroku，我收到的数据库错误说明了这一点：

PG::UndefinedTable: ERROR:  relation "topics" does not exist
: ALTER TABLE "blogs" ADD CONSTRAINT "fk_rails_7f5637ea0d"
FOREIGN KEY ("topic_id")
  REFERENCES "topics" ("id")

似乎在说我没有topic_id的引用，但它在我的schema.rb文件中：

ActiveRecord::Schema.define(version: 20170930175841) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  create_table "blogs", force: :cascade do |t|
    t.string "title"
    t.text "body"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string "slug"
    t.integer "status", default: 0
    t.bigint "topic_id"
    t.index ["slug"], name: "index_blogs_on_slug", unique: true
    t.index ["topic_id"], name: "index_blogs_on_topic_id"
  end

  create_table "comments", force: :cascade do |t|
    t.text "content"
    t.bigint "user_id"
    t.bigint "blog_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["blog_id"], name: "index_comments_on_blog_id"
    t.index ["user_id"], name: "index_comments_on_user_id"
  end

  create_table "friendly_id_slugs", force: :cascade do |t|
    t.string "slug", null: false
    t.integer "sluggable_id", null: false
    t.string "sluggable_type", limit: 50
    t.string "scope"
    t.datetime "created_at"
    t.index ["slug", "sluggable_type", "scope"], name: "index_friendly_id_slugs_on_slug_and_sluggable_type_and_scope", unique: true
    t.index ["slug", "sluggable_type"], name: "index_friendly_id_slugs_on_slug_and_sluggable_type"
    t.index ["sluggable_id"], name: "index_friendly_id_slugs_on_sluggable_id"
    t.index ["sluggable_type"], name: "index_friendly_id_slugs_on_sluggable_type"
  end

  create_table "portfolios", force: :cascade do |t|
    t.string "title"
    t.string "subtitle"
    t.text "body"
    t.text "main_image"
    t.text "thumb_image"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.integer "position"
  end

  create_table "skills", force: :cascade do |t|
    t.string "title"
    t.integer "percent_utilized"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.text "badge"
  end

  create_table "technologies", force: :cascade do |t|
    t.string "name"
    t.bigint "portfolio_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["portfolio_id"], name: "index_technologies_on_portfolio_id"
  end

  create_table "topics", force: :cascade do |t|
    t.string "title"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
  end

  create_table "users", force: :cascade do |t|
    t.string "name"
    t.string "email", default: "", null: false
    t.string "encrypted_password", default: "", null: false
    t.string "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer "sign_in_count", default: 0, null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.inet "current_sign_in_ip"
    t.inet "last_sign_in_ip"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string "roles"
    t.index ["email"], name: "index_users_on_email", unique: true
    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
  end

  add_foreign_key "blogs", "topics"
  add_foreign_key "comments", "blogs"
  add_foreign_key "comments", "users"
  add_foreign_key "technologies", "portfolios"
end

如何解决与我在schema.rb文件中看到的错误相冲突的错误？错误告诉我进入postgres并添加该约束项吗？如果是这样，我该怎么做呢？

我查看过这个文档：

https://devcenter.heroku.com/articles/postgres-logs-errors

但找不到任何远程帮助此案例的内容。我还审查了这份文件：

PG::UndefinedTable: ERROR: relation "..." does not exist

但我不确定这是不是答案。如果我理解上面的SO文档，我的主题表应该在博客表之前创建，但不是因为时间戳显示博客是在主题表之前创建的。当我查看它时，确实在我的迁移中的主题表之前创建了博客表。

那么纠正这些日期以便最先创建表格的最简洁，最简单的方法是什么？假设这是问题所在。

我已经确认主题表确实存在于本地：

ActiveRecord::Base.connection.tables
 => ["schema_migrations", "ar_internal_metadata", "friendly_id_slugs", "skills", "portfolios", "users", "topics", "blogs", "comments", "technologies"]
2.3.3 :002 >

然而，当我这样做时：

$ psql postgres
psql (9.6.1)
Type "help" for help.

postgres=# SELECT * FROM pg_tables WHERE tablename = 'topics';
 schemaname | tablename | tableowner | tablespace | hasindexes | hasrules | hastriggers | rowsecurity
------------+-----------+------------+------------+------------+----------+-------------+-------------
(0 rows)

postgres=#

我通过SO社区成员的帮助意识到我需要切换到正确的数据库，一旦我这样做，我就确认我有＃34;主题＆＃34;表：

postgres=# \connect <db_name>_development
You are now connected to database "<db_name>_development" as user "danale".
<db_name>_development=# SELECT * FROM pg_tables WHERE tablename = 'topics';
 schemaname | tablename | tableowner | tablespace | hasindexes | hasrules | hastriggers | rowsecurity
------------+-----------+------------+------------+------------+----------+-------------+-------------
 public     | topics    | danale     |            | t          | f        | t           | f
(1 row)

Answer 1

表topics必须在您创建FK引用之前必须存在。

帮助诊断情况的常规SQL工具

首先，确保在各种测试中连接到正确的数据库。在正确的数据库集群（主机，端口）！

SELECT current_database();

与psql postgres连接，连接到名为＆＃34; postgres＆＃34;的数据库。（标准维护db，不要在那里创建对象，不管它。）

你确定，桌子存在吗？检查 - 在正确的数据库中：

SELECT *
FROM   pg_tables
WHERE  tablename = 'topics';

多个模式中可以有多个同名的表。

更多：

How to check if a table exists in a given schema

架构（schemaname）是否出现在您当前的search_path？

中

SHOW search_path;

更多：

How does the search_path influence identifier resolution and the "current schema"

Answer 2

REFERENCES "topics" ("id")似乎引用了＆＃34;主题＆＃34;表格和字段＆＃34; id＆＃34;在里面。我没有看到它在创建表上创建？不可否认，这已经很多年了，但你不应该指现有的专栏吗？

如何解决此Heroku数据库错误？

2 个答案:

帮助诊断情况的常规SQL工具