Python Peewee execute_sql（）示例 [英] Python Peewee execute_sql() example

问题描述

我将Peewee模块用作项目的ORM。

I am using the Peewee module as the ORM for my project.

我已经阅读了整个文档，没有清晰的
示例如何处理db.execute_sql（）的结果。

I read the entire documentation, there is no clear example on how to process the result from db.execute_sql().

我跟踪了代码，只能找到db.execute_sql（）返回游标。

I traced the code, only can find db.execute_sql() return back the cursor.

是否有人知道如何处理游标，例如对其进行迭代并从复杂的select语句获取
的结果。

Does anyone knows how to process the cursor, such as iterate over it and get back the result from complex select statement.

更新：我刚刚从peewee文件夹中找到了以下源代码，它应该有助于
我解决此问题。

Update: I just found the following source code from peewee folder, it should help me to resolve this problem.

class QueryResultWrapper(object):
    """
    Provides an iterator over the results of a raw Query, additionally doing
    two things:
    - converts rows from the database into python representations
    - ensures that multiple iterations do not result in multiple queries
    """
    def __init__(self, model, cursor, meta=None):
        self.model = model
        self.cursor = cursor

        self.__ct = 0
        self.__idx = 0

        self._result_cache = []
        self._populated = False
        self._initialized = False

        if meta is not None:
            self.column_meta, self.join_meta = meta
        else:
            self.column_meta = self.join_meta = None

    def __iter__(self):
        self.__idx = 0

        if not self._populated:
            return self
        else:
            return iter(self._result_cache)

    def process_row(self, row):
        return row

    def iterate(self):
        row = self.cursor.fetchone()
        if not row:
            self._populated = True
            raise StopIteration
        elif not self._initialized:
            self.initialize(self.cursor.description)
            self._initialized = True
        return self.process_row(row)

    def iterator(self):
        while True:
            yield self.iterate()

    def next(self):
        if self.__idx  self.__ct):
            try:
                self.next()
            except StopIteration:
                break

推荐答案

Peewee返回一个游标。然后，您可以使用db-api 2对其进行迭代：

Peewee returns a cursor. Then you can use the db-api 2 to iterate over it:

cursor = db.execute_sql('select * from tweets;')
for row in cursor.fetchall():
    print(row)

cursor = db.execute_sql('select count(*) from tweets;')
res = cursor.fetchone()
print('Total: ', res[0])

文档： Database.execute_sql

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