最近在學(xué)flask ，我是跟《flask-web開發(fā)：基于Python的Web應(yīng)用開發(fā)實(shí)戰(zhàn)》 這本書一步一步實(shí)現(xiàn)的，也就是在github上 flasky 這個(gè)項(xiàng)目。中間遇到一兩個(gè)比較大的問題，記錄下來*

flask + heroku +postagres

1. 問題一：

在成功 heroku服務(wù)器git后， 初始和更新數(shù)據(jù)庫的時(shí)候，如類似以下錯(cuò)誤:

heroku run python manager.py deploy # 初始和更新數(shù)據(jù)庫

Running python manager.py deploy on ? flasky-blog-mirui... ? 
Running python manager.py deploy on ? flasky-blog-mirui... ? starting, run.7767 (Free)
Running python manager.py deploy on ? flasky-blog-mirui... up, run.7767 (Free)

INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> 8d6dba4cf1a4, the second migration

psycopg2.errors.UndefinedTable: relation "users" does not exist

sqlalchemy.exc.ProgrammingError: (psycopg2.errors.UndefinedTable) relation "users" does not exist

大致是上面錯(cuò)誤，具體看下列錯(cuò)誤一**

1. 一開始，看報(bào)錯(cuò)提示，以為是自己的 psycopg2出錯(cuò)了（我安裝二進(jìn)制包psycopg2-binary,因?yàn)榘惭b不上psycopg2）

2. 以為是數(shù)據(jù)庫 結(jié)構(gòu)有點(diǎn)問題，后面優(yōu)化數(shù)據(jù)結(jié)構(gòu)與類型，還是報(bào)錯(cuò)。

3. 執(zhí)行git push heroku master，可以運(yùn)行，打開APP的鏈接，只要是動(dòng)態(tài)連接到數(shù)據(jù)庫的頁面都會(huì)500 Internal Server Error報(bào)服務(wù)器錯(cuò)。顯然是連接數(shù)據(jù)庫出錯(cuò)

4. 執(zhí)行 heroku logs -t 發(fā)現(xiàn)會(huì)報(bào)類似sqlalchemy.exc.ProgrammingError: (psycopg2.errors.UndefinedTable) relation "posts" does not exist這樣的錯(cuò)，與之前一樣的錯(cuò)。

5. 本地也使用本地postagres庫，一切正常。排除數(shù)據(jù)庫出錯(cuò)，代碼問題。

無奈～～，想起之前在 stackoverflow搜索 Internal Server Error+flask+heroku就看到有人說是把migrations版本都刪掉,無奈，做個(gè)備份，把migrations文件夾刪掉，git 和初始化后，居然沒有報(bào)錯(cuò)，ztyd神奇！

解決方法：

在確定，代碼沒問題，在本地的虛擬環(huán)境正常運(yùn)行可采取以下操作：

刪掉煩人的數(shù)據(jù)庫版本控制migrations文件夾

rm -rf ./migrations
git add .
git commit -am '馬上要好了'
git push heroku master
heroku run python manage,py deploy

好了，這就可以打開你的heroku app 了。

歡迎你們來我的 heroku app flasky-blog-mirui ,記得給我留言哦～～～

* 錯(cuò)誤一

heroku run python manager.py deploy # 初始和更新數(shù)據(jù)庫
Running python manager.py deploy on ? flasky-blog-mirui... ? 
Running python manager.py deploy on ? flasky-blog-mirui... ? starting, run.7767 (Free)
Running python manager.py deploy on ? flasky-blog-mirui... up, run.7767 (Free)

INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> 8d6dba4cf1a4, the second migration
Traceback (most recent call last):
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1244, in _execute_context
    cursor, statement, parameters, context
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/default.py", line 552, in do_execute
    cursor.execute(statement, parameters)
psycopg2.errors.UndefinedTable: relation "users" does not exist


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manager.py", line 83, in <module>
    manager.run()
  File "/app/.heroku/python/lib/python3.6/site-packages/flask_script/__init__.py", line 417, in run
    result = self.handle(argv[0], argv[1:])
  File "/app/.heroku/python/lib/python3.6/site-packages/flask_script/__init__.py", line 386, in handle
    res = handle(*args, **config)
  File "/app/.heroku/python/lib/python3.6/site-packages/flask_script/commands.py", line 216, in __call__
    return self.run(*args, **kwargs)
  File "manager.py", line 67, in deploy
    upgrade()
  File "/app/.heroku/python/lib/python3.6/site-packages/flask_migrate/__init__.py", line 95, in wrapped
    f(*args, **kwargs)
  File "/app/.heroku/python/lib/python3.6/site-packages/flask_migrate/__init__.py", line 280, in upgrade
    command.upgrade(config, revision, sql=sql, tag=tag)
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/command.py", line 276, in upgrade
    script.run_env()
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/script/base.py", line 475, in run_env
    util.load_python_file(self.dir, "env.py")
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/util/pyfiles.py", line 90, in load_python_file
    module = load_module_py(module_id, path)
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/util/compat.py", line 177, in load_module_py
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "migrations/env.py", line 96, in <module>
    run_migrations_online()
  File "migrations/env.py", line 90, in run_migrations_online
    context.run_migrations()
  File "<string>", line 8, in run_migrations
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/runtime/environment.py", line 839, in run_migrations
    self.get_context().run_migrations(**kw)
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/runtime/migration.py", line 362, in run_migrations
    step.migration_fn(**kw)
  File "/app/migrations/versions/8d6dba4cf1a4_the_second_migration.py", line 21, in upgrade
    op.add_column('users', sa.Column('confirmed', sa.Boolean(), nullable=True))
  File "<string>", line 8, in add_column
  File "<string>", line 3, in add_column
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/operations/ops.py", line 1904, in add_column
    return operations.invoke(op)
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/operations/base.py", line 345, in invoke
    return fn(self, operation)
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/operations/toimpl.py", line 131, in add_column
    operations.impl.add_column(table_name, column, schema=schema)
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/ddl/impl.py", line 231, in add_column
    self._exec(base.AddColumn(table_name, column, schema=schema))
  File "/app/.heroku/python/lib/python3.6/site-packages/alembic/ddl/impl.py", line 134, in _exec
    return conn.execute(construct, *multiparams, **params)
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 988, in execute
    return meth(self, multiparams, params)
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/sql/ddl.py", line 72, in _execute_on_connection
    return connection._execute_ddl(self, multiparams, params)
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1050, in _execute_ddl
    compiled,
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1248, in _execute_context
    e, statement, parameters, cursor, context
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1466, in _handle_dbapi_exception
    util.raise_from_cause(sqlalchemy_exception, exc_info)
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 398, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 152, in reraise
    raise value.with_traceback(tb)
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1244, in _execute_context
    cursor, statement, parameters, context
  File "/app/.heroku/python/lib/python3.6/site-packages/sqlalchemy/engine/default.py", line 552, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.ProgrammingError: (psycopg2.errors.UndefinedTable) relation "users" does not exist