Introduction
In this guide, we will be focusing on the frappe.db.get_list feature of Empress. The frappe.db.get_list feature is a significant tool for developers working with Empress, allowing the retrieval and manipulation of data in a structured and efficient manner. This feature provides an ORM (Object-Relational Mapping) wrapper for SELECT queries, allowing for the application of user permissions and the return of specified fields for records from a doctype table.
Understanding the frappe.db.get_list Feature
The frappe.db.get_list feature enables developers to retrieve data from a doctype table in a structured list format. By default, the method returns a list of dictionaries. However, developers have the option to specify a particular field using the pluck keyword argument. This flexibility allows for streamlined data extraction and manipulation, enhancing the overall development process.
frappe.db.get_list('Employee', pluck='name')
This feature also allows for the combination of filters and other arguments, such as ‘order_by’, ‘start’, and ‘page_length’, to further refine the data retrieval process.
frappe.db.get_list('Task',
filters={
'status': 'Open'
},
fields=['subject', 'date'],
order_by='date desc',
start=10,
page_length=20,
as_list=True
)
Implementation and Modification
The frappe.db.get_list feature is implemented using Python and the Empress framework. It uses SQL queries wrapped in an ORM layer to allow for easy manipulation and retrieval of data from a doctype table.
Modifying this feature to suit specific requirements involves changing the arguments passed to the frappe.db.get_list function. These arguments include the filters, fields, order_by, group_by, start, and page_length parameters.
Debugging the Feature
Debugging the frappe.db.get_list feature involves understanding the underlying SQL and Python code powering the feature. Developers should familiarize themselves with SQL SELECT queries and Python’s handling of dictionaries and lists.
If an error occurs when using the feature, the first step is to inspect the error message. This often provides clues about the nature of the issue, such as a missing field or an incorrect data type.
User Roles and Permissions
The frappe.db.get_list feature also applies user permissions for the records of the session user. This ensures that data is only accessed by users who have the required permissions, enhancing system security.
User roles and permissions can be managed within the Empress system. Developers can define roles and assign them to users, controlling the access each user has to various doctype tables.
Summary
The frappe.db.get_list feature is a powerful tool in Empress, providing developers with an efficient and flexible way to retrieve and manipulate data. Its ability to apply user permissions, combined with its flexible data retrieval options, makes it a key feature in the development and customization of business solutions.
By understanding and effectively using this feature, developers can ensure they are leveraging the full potential of Empress in their software development and customization processes.