嘗試面向物件的python腳本時未定義的變數'self'

我正在嘗試構建一個程式來自動創建從 MySQL 到 BigQuery 的批處理管道，并且我隨機收到此 linting 錯誤：“未定義變數‘self’”。

DESTINATION_TABLE_FORMAT 類常量無法訪問 self.environment() 因為它給出了未定義的變數 self 錯誤。

當我將 data_lake_paths 向內移動一個縮進時，它開始作業，但我不再能夠通過呼叫變數來訪問它。

任何幫助將非常感激

class MySQLBatchPipeline:
    '''
    Class to generate MySQL batch pipelines that store CSV's
    in GCS then import them into BigQuery
    '''
    export_format='CSV'
    DESTINATION_TABLE_FORMAT = self.get_environment()   '.{dataset}.{table}' #<- linter flags this as "Undefined Variable 'self'"
    def __init__(
        self,
        dag,
        sql_directory,
        gcp_project_id,
        mysql_connection_id,
        source_schema,
        source_table,
        gcs_connection_id,
        bq_connection_id,
        gcs_bucket,
        destination_staging_schema,
        destination_schema,
        destination_table,
        environment,
        time_delay,
        country,
        max_file_size: int=int(50e6),
    ):
        self.dag = dag,
        self.sql_directory = sql_directory,
        self.gcp_project_id = gcp_project_id,
        self.mysql_connection_id = mysql_connection_id,
        self.source_schema = source_schema,
        self.source_table = source_table,
        self.gcs_connection_id = gcs_connection_id,
        self.bq_connection_id = bq_connection_id,
        self.gcs_bucket = gcs_bucket,
        self.destination_staging_schema = destination_staging_schema,
        self.destination_schema = destination_schema,
        self.destination_table = destination_table,
        self.time_delay = time_delay,
        self.environment = environment,
        self.max_file_size = max_file_size,
        self.queries = self.get_pipeline_queries()
        self.schema_file = self.get_schema_files()
        self.country = country
    
    # variables
    data_lake_paths = GoogleCloudStoragePaths(self.destination_table) #<- the same Undefined Variable 'self' error is flagged here. 

uj5u.com熱心網友回復：

自從

    def __init__(self, ...):
        ...
    # this variable
    data_lake_paths = GoogleCloudStoragePaths(self.destination_table)

在任何接受self引數的類方法之外，python 會將其設定為類變數而不是實體變數，因此不會self傳遞任何引數（這就是Undefined Variable 'self'發生這種情況的原因）。

把它放在__init__方法或其他方法中，它應該可以作業。

uj5u.com熱心網友回復：

直接定義在類體內的變數不能使用self，只有方法中的變數可以。相反，只需將該變數的定義移動到__init__函式中。如果即使__init__沒有運行也需要變數，那么只需None在類主體中設定它即可。

代碼：

class MySQLBatchPipeline:
    '''
    Class to generate MySQL batch pipelines that store CSV's
    in GCS then import them into BigQuery
    '''
    export_format='CSV'
    DESTINATION_TABLE_FORMAT = self.get_environment()   '.{dataset}.{table}'
    
    # Declare here if necessary
    data_lake_paths = None

    def __init__(
        self,
        dag,
        sql_directory,
        gcp_project_id,
        mysql_connection_id,
        source_schema,
        source_table,
        gcs_connection_id,
        bq_connection_id,
        gcs_bucket,
        destination_staging_schema,
        destination_schema,
        destination_table,
        environment,
        time_delay,
        country,
        max_file_size: int=int(50e6),
    ):
        self.dag = dag,
        self.sql_directory = sql_directory,
        self.gcp_project_id = gcp_project_id,
        self.mysql_connection_id = mysql_connection_id,
        self.source_schema = source_schema,
        self.source_table = source_table,
        self.gcs_connection_id = gcs_connection_id,
        self.bq_connection_id = bq_connection_id,
        self.gcs_bucket = gcs_bucket,
        self.destination_staging_schema = destination_staging_schema,
        self.destination_schema = destination_schema,
        self.destination_table = destination_table,
        self.time_delay = time_delay,
        self.environment = environment,
        self.max_file_size = max_file_size,
        self.queries = self.get_pipeline_queries()
        self.schema_file = self.get_schema_files()
        self.country = country

        # Define here
        data_lake_paths = GoogleCloudStoragePaths(self.destination_table)

標籤：

上一篇：PHP中的組合與聚合

下一篇：c 兩個類相互參考