Declare Node & Edge Types¶

Node and edge types are lightweight descriptors that tell Panel-ReactFlow what kind of data a node or edge carries. A type defines a name, an optional display label, optional input/output ports (for nodes), and an optional JSON Schema for its data payload.

Types are separate from editors. A type says "a task node has a status string and a priority integer"; an editor says "render a dropdown and a number input for those fields." This separation lets you reuse the same type with different editors, or rely on the auto-generated form.

Screenshot: multiple node types with different schemas

Node types¶

Use NodeType to describe a node type. Provide inputs and outputs to control the handles (ports) shown on each side of the node.

from panel_reactflow import NodeType

task_schema = {
    "type": "object",
    "properties": {
        "status": {"type": "string", "enum": ["idle", "running", "done"]},
        "priority": {"type": "integer"},
    },
}

node_types = {
    "task": NodeType(
        type="task",
        label="Task",
        schema=task_schema,
        inputs=["in"],
        outputs=["out"],
    ),
}

Edge types¶

Use EdgeType to describe an edge type. Edges with a schema get the same auto-generated editor support as nodes.

from panel_reactflow import EdgeType

edge_types = {
    "pipe": EdgeType(
        type="pipe",
        label="Pipe",
        schema={
            "type": "object",
            "properties": {
                "throughput": {"type": "number"},
                "protocol": {"type": "string", "enum": ["tcp", "udp", "http"]},
            },
        },
    ),
}

Schema sources¶

The schema field accepts multiple formats. All are normalized to JSON Schema before being sent to the frontend or used by editors.

Source	Example
JSON Schema dict	`{"type": "object", "properties": {...}}`
Param class	A `param.Parameterized` subclass
Pydantic model	A `pydantic.BaseModel` subclass

Param class shorthand¶

import param
from panel_reactflow import NodeType

class Job(param.Parameterized):
    status = param.Selector(objects=["idle", "running", "done"])
    retries = param.Integer(default=0)

node_types = {"job": NodeType(type="job", label="Job", schema=Job)}

Pydantic model shorthand¶

from pydantic import BaseModel
from panel_reactflow import NodeType

class Config(BaseModel):
    host: str = "localhost"
    port: int = 8080

node_types = {"config": NodeType(type="config", label="Config", schema=Config)}

Register on ReactFlow¶

Pass types as dictionaries keyed by type name.

flow = ReactFlow(
    nodes=nodes,
    edges=edges,
    node_types=node_types,
    edge_types=edge_types,
)

Types without a schema still work — the node or edge simply has no schema-driven validation or auto-generated form.