Database 如何使用 Gramex FormHandler 动态(在运行时)创建或更改数据库模式

FormHandler支持defining columns in the spec.

例如，此配置创建了一个名为profile的表，其中包含4列:user、password、age和id.

url:
    handler: FormHandler
    kwargs:
      url: 'postgresql://$USER:$PASS@server/db'       # Pick any database
      table: profile              # Pick any table name to create
      id: id                      # The "id" column is primary key
      # Define your table's columns
      columns:
        user: TEXT                # Use any SQL type allowed by DB
        password: VARCHAR(40)     # including customizations
        age:
          type: INTEGER           # You can also specify as a dict
          nullable: true          # Allows NULL values for this field
          default: 0              # that default to zero
        id:
          type: INTEGER           # Define an integer ID column
          primary_key: true       # as a primary key
          autoincrement: true     # that auto-increments

但如果在运行时需要更改，例如当用户单击按钮时，可以使用FunctionHandler和gramex.data.alter()

例如，将此添加到您的gramex.yaml:

url:
  alter:
    pattern: /alter
    handler: FunctionHandler
    kwargs:
      # You can decide the columns dynamically here
      function: >
        gramex.data.alter(url, table, columns={
           col: 'TEXT' for col in handler.args.get('col', [])
        })

调用/alter?col=email时，函数会添加email列作为文本.

注意:没有删除列的选项.