Model Events

Model events are event mechanisms that automatically trigger based on model data operations, implementing data change monitoring and response based on event subscription-publish patterns. They are responsible for monitoring model CRUD operations, providing rich trigger timing options and supporting conditional filtering with field-level trigger control, supporting both synchronous and asynchronous execution modes, suitable for data auditing, business rule execution, message notification, and other scenarios.

The hierarchical structure of model event elements is Meta (events.Meta) → Type (events.ModelType) → Instance. Developers can quickly create model event instance elements through JitAI's visual development tools.

Of course, developers can also create their own Type elements or modify the official events.ModelType element provided by JitAi in their own App to implement their own encapsulation.

Quick Start

Basic Configuration Example

Recommended Directory Structure
events/
└── UserDataAudit/           # User data audit event
    ├── e.json              # Event configuration file
    ├── inner.py            # Internal function implementation (when funcType is Inner)
    └── __init__.py         # Package initialization file

e.json - Event Configuration File
{
  "type": "events.ModelType",
  "title": "User Data Audit",
  "sender": "models.UserModel",
  "operate": "UpdateAfter",
  "funcType": "Inner",
  "asyncType": false,
  "filter": "Q(status='active')",
  "fields": ["name", "email", "status"],
  "enable": 1,
  "backendBundleEntry": "."
}

inner.py - Event Handler Function
def customFunc(eventOutData):
    """
    User data change audit
    
    Args:
        eventOutData: JitDict type, contains event-related data
    """
    model = eventOutData.model.value
    opt_type = eventOutData.optType.value
    prev_data = eventOutData.prevData.value
    post_data = eventOutData.postData.value
    
    print(f"Model {model} performed {opt_type} operation")
    print(f"Data before change: {prev_data}")
    print(f"Data after change: {post_data}")

__init__.py
from .inner import customFunc

Configuration Properties Description

Property Name	Type	Description	Default Value	Required
type	string	Fixed value `events.ModelType`	-	Yes
title	string	Event title	-	Yes
sender	string	FullName of monitored model	-	Yes
operate	string	Operation type, see operation type enumeration	-	Yes
funcType	string	Function type: `Global` \| `Inner`	`Global`	No
func	string	Global function path (required when funcType is Global)	-	No
asyncType	boolean	Whether to execute asynchronously	`false`	No
filter	string	Q expression filter condition	-	No
fields	array	Trigger field list, empty means monitor all fields	`[]`	No
enable	number	Whether enabled: 1 enabled, 0 disabled	`1`	No

Operation Type Enumeration:

AddBefore - Trigger before adding data
AddAfter - Trigger after adding data
UpdateBefore - Trigger before updating data
UpdateAfter - Trigger after updating data
DeleteBefore - Trigger before deleting data
DeleteAfter - Trigger after deleting data
FieldUpdateAfter - Trigger after any write operation

Methods

getSender

Get the real sender identifier of the event.

Return Value

Type	Description
string	Sender identifier in format `{modelFullName}_{operate}`

Usage Example

Get Event Sender
# In event handler function
user_event = app.getElement("events.UserDataAudit")
sender = user_event.getSender()
print(f"Event sender: {sender}")  # Output: models.UserModel_UpdateAfter

isValid

Check whether the event should trigger, comprehensively validating filter conditions and field change conditions.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
rowObj	object	Row data object containing prevData and postData	`None`	No

Return Value

Type	Description
boolean	`True` means should trigger event, `False` means not trigger

Usage Example

Event Validity Check
# Simulate row data object
row_obj = type('obj', (), {
    'value': {
        'model': 'models.UserModel',
        'prevData': {'id': 1, 'name': '张三', 'status': 'inactive'},
        'postData': {'id': 1, 'name': '张三', 'status': 'active'}
    }
})()

user_event = app.getElement("events.UserDataAudit")
is_valid = user_event.isValid(row_obj)
print(f"Whether event triggers: {is_valid}")

isFilterValid

Validate whether filter conditions are satisfied.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
rowObj	object	Row object containing data	`None`	No

Return Value

Type	Description
boolean	Whether filter conditions are satisfied

isFieldValid

Validate whether field change conditions are satisfied.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
rowObj	object	Row object containing data	`None`	No

Return Value

Type	Description
boolean	Whether field change conditions are satisfied

buildEmptyDict

Build empty dictionary structure of the model, containing all model fields with None values.

Return Value

Type	Description
dict	Empty dictionary containing all model fields

Usage Example

Build Empty Dictionary
user_event = app.getElement("events.UserDataAudit")
empty_dict = user_event.buildEmptyDict()
print(empty_dict)  # {'id': None, 'name': None, 'email': None, 'status': None}

call

Execute event function and record execution time.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
*args	any	Positional arguments passed to event function	-	No
**kwargs	any	Keyword arguments passed to event function	-	No

Return Value

Type	Description
any	Return value of event function

Usage Example

Manually Call Event
user_event = app.getElement("events.UserDataAudit")

# Construct event data
event_data = app.newVariable({
    "name": "eventOutData",
    "title": "Event Data",
    "dataType": "JitDict",
    "variableList": [
        {"name": "model", "title": "Model", "dataType": "Stext"},
        {"name": "optType", "title": "Operation Type", "dataType": "Stext"},
        {"name": "prevData", "title": "Data Before Change", "dataType": "RowData"},
        {"name": "postData", "title": "Data After Change", "dataType": "RowData"}
    ]
})

event_data.value = {
    "model": "models.UserModel",
    "optType": "UpdateAfter",
    "prevData": {"id": 1, "name": "张三"},
    "postData": {"id": 1, "name": "李四"}
}

# Call event
result = user_event.call(event_data)

handleNode

Process event node before executing event function, allowing customized operations on the node.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
node	object	Event node object	-	Yes
*args	any	Event function arguments	-	No
**kwargs	any	Event function keyword arguments	-	No

Return Value

Type	Description
tuple	Tuple containing processed (node, args, kwargs)

buildTaskParams

Construct asynchronous task parameters, serializing event parameters into storable format.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
*args	any	Event function arguments	-	No
**kwargs	any	Event function keyword arguments	-	No

Return Value

Type	Description
dict	Serialized task parameters

recoverTaskParams

Recover event function parameters from task parameters.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
taskParam	dict	Task parameter dictionary	-	Yes

Return Value

Type	Description
tuple	Tuple containing recovered (args, kwargs)

createTask

Create asynchronous event task.

Parameter Details

Parameter Name	Type	Description	Default Value	Required
taskParams	dict	Task parameters	-	Yes
nodeId	string	Event node ID	-	Yes
requestId	string	Request ID	-	Yes

Properties

name

Event fullName identifier, read-only property.

sender

FullName of monitored model, read-only property.

funcType

Function type, optional values are Global or Inner, read-only property.

func

Global function path specified when funcType is Global, read-only property.

type

Event type, fixed as events.ModelType, read-only property.

enable

Whether event is enabled, 1 for enabled, 0 for disabled, read-only property.

title

Event display title, read-only property.

asyncType

Whether to execute event asynchronously, read-only property.

callTime

Last execution time of event, may be None (never executed), read-only property.

operate

Monitored operation type, corresponding to EventTypeEnum enumeration value, read-only property.

filterQ

Q expression filter condition string, read-only property.

fields

Specified trigger field list, empty list means monitor all fields, read-only property.

Advanced Features

Conditional Filtering and Field Monitoring

Model events support precise trigger control, achieving accurate event response through filter conditions and field monitoring.

Advanced Filter Configuration
{
  "type": "events.ModelType",
  "title": "VIP User Status Change Monitoring",
  "sender": "models.UserModel",
  "operate": "UpdateAfter",
  "filter": "Q(user_type='vip') & Q(status__in=['active', 'inactive'])",
  "fields": ["status", "level"],
  "funcType": "Global",
  "func": "services.NotificationSvc.sendVipStatusAlert",
  "asyncType": true
}

Asynchronous Event Processing

For complex business logic or time-consuming operations, asynchronous execution can be enabled to avoid blocking the main process.

Asynchronous Event Handler Function
def customFunc(eventOutData):
    """
    Asynchronously process user data synchronization
    """
    import time
    
    user_data = eventOutData.postData.value
    print(f"Start synchronizing user data: {user_data['name']}")
    
    # Simulate time-consuming operation
    time.sleep(2)
    
    # Call external API to synchronize data
    sync_service = app.getElement("services.DataSyncSvc")
    sync_service.syncUserToThirdParty(user_data)
    
    print(f"User data synchronization completed: {user_data['name']}")

Multi-Model Event Coordination

Implement complex business process control by combining multiple model events.

Order Status Change Event
{
  "type": "events.ModelType", 
  "title": "Inventory Update After Order Completion",
  "sender": "models.OrderModel",
  "operate": "UpdateAfter",
  "filter": "Q(status='completed')",
  "fields": ["status"],
  "funcType": "Global", 
  "func": "services.InventorySvc.updateStock"
}

Inventory Change Notification Event
{
  "type": "events.ModelType",
  "title": "Low Stock Warning",
  "sender": "models.InventoryModel", 
  "operate": "UpdateAfter",
  "filter": "Q(quantity__lt=10)",
  "fields": ["quantity"],
  "funcType": "Global",
  "func": "services.AlertSvc.sendLowStockWarning"
}

Quick Start​

Basic Configuration Example​

Configuration Properties Description​

Methods​

getSender​

Return Value​

Usage Example​

isValid​

Parameter Details​

Return Value​

Usage Example​

isFilterValid​

Parameter Details​

Return Value​

isFieldValid​

Parameter Details​

Return Value​

buildEmptyDict​

Return Value​

Usage Example​

call​

Parameter Details​

Return Value​

Usage Example​

handleNode​

Parameter Details​

Return Value​

buildTaskParams​

Parameter Details​

Return Value​

recoverTaskParams​

Parameter Details​

Return Value​

createTask​

Parameter Details​

Properties​

name​

sender​

funcType​

func​

type​

enable​

title​

asyncType​

callTime​

operate​

filterQ​

fields​

Advanced Features​

Conditional Filtering and Field Monitoring​

Asynchronous Event Processing​

Multi-Model Event Coordination​

Quick Start

Basic Configuration Example

Configuration Properties Description

Methods

getSender

Return Value

Usage Example

isValid

Parameter Details

Return Value

Usage Example

isFilterValid

Parameter Details

Return Value

isFieldValid

Parameter Details

Return Value

buildEmptyDict

Return Value

Usage Example

call

Parameter Details

Return Value

Usage Example

handleNode

Parameter Details

Return Value

buildTaskParams

Parameter Details

Return Value

recoverTaskParams

Parameter Details

Return Value

createTask

Parameter Details

Properties

name

sender

funcType

func

type

enable

title

asyncType

callTime

operate

filterQ

fields

Advanced Features

Conditional Filtering and Field Monitoring

Asynchronous Event Processing

Multi-Model Event Coordination