Validation

Custom nodes need to have at least one Handle component to be connectable. You can pass a validation function isValidConnection to the ReactFlow component in order to check if a new connection is valid and should be added.

/* xyflow theme files. Delete these to start from our base */
 
.react-flow {
  --xy-background-color: #f7f9fb;
  /* Custom Variables */
  --xy-theme-selected: #f57dbd;
  --xy-theme-hover: #c5c5c5;
  --xy-theme-edge-hover: black;
  --xy-theme-color-focus: #e8e8e8;
 
  /* Built-in Variables see https://reactflow.dev/learn/customization/theming */
  --xy-node-border-default: 1px solid #ededed;
 
  --xy-node-boxshadow-default: 0px 3.54px 4.55px 0px #00000005, 0px 3.54px 4.55px 0px #0000000d, 0px 0.51px 1.01px 0px #0000001a;
 
  --xy-node-border-radius-default: 8px;
 
  --xy-handle-background-color-default: #ffffff;
  --xy-handle-border-color-default: #aaaaaa;
 
  --xy-edge-label-color-default: #505050;
  --xy-node-background-color-default: #ffffff;
  --xy-theme-panel-bg: #ffffff;
  --xy-theme-panel-text: #111827;
  --xy-theme-resize-handle-bg: #ffffff;
  --xy-theme-focus-border: #d9d9d9;
  --xy-theme-muted-bg: #f3f4f6;
  --xy-theme-subtle-border: #d1d5db;
}
 
.react-flow.dark {
  --xy-background-color: #101012;
  --xy-node-background-color-default: #1a1b1e;
  --xy-node-border-default: 1px solid #303238;
  --xy-handle-background-color-default: #141519;
  --xy-handle-border-color-default: #5a5d66;
  --xy-edge-label-color-default: #e6e7ea;
  --xy-theme-hover: #7a7d86;
  --xy-theme-edge-hover: #f3f4f6;
  --xy-theme-panel-bg: #141519;
  --xy-theme-panel-text: #f3f4f6;
  --xy-theme-resize-handle-bg: #141519;
  --xy-theme-focus-border: #5f6470;
  --xy-theme-muted-bg: #24262c;
  --xy-theme-subtle-border: #3f434c;
  --xy-node-boxshadow-default: none;
  --xy-theme-color-focus: #4b4e57;
  --color-background: #1a1b1e;
  --color-hover-bg: #24262c;
  --color-disabled: #8b9099;
}
 
.react-flow {
  background-color: var(--xy-background-color);
}
 
/* Customizing Default Theming */
 
.react-flow__node {
  box-shadow: var(--xy-node-boxshadow-default);
  border-radius: var(--xy-node-border-radius-default);
  background-color: var(--xy-node-background-color-default);
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 10px;
  font-size: 12px;
  flex-direction: column;
  border: var(--xy-node-border-default);
  color: var(--xy-node-color, var(--xy-node-color-default));
}
 
.react-flow__node.selectable:focus {
  box-shadow: 0px 0px 0px 4px var(--xy-theme-color-focus);
  border-color: var(--xy-theme-focus-border);
}
 
.react-flow__node.selectable:focus:active {
  box-shadow: var(--xy-node-boxshadow-default);
}
 
.react-flow__node.selectable:hover,
.react-flow__node.draggable:hover {
  border-color: var(--xy-theme-hover);
}
 
.react-flow__node.selectable.selected {
  border-color: var(--xy-theme-selected);
  box-shadow: var(--xy-node-boxshadow-default);
}
 
.react-flow__node-group {
  background-color: rgba(207, 182, 255, 0.4);
  border-color: #9e86ed;
}
 
.react-flow.dark .react-flow__node-group {
  background-color: rgba(123, 107, 148, 0.22);
  border-color: #7b6b94;
}
 
.react-flow__edge.selectable:hover .react-flow__edge-path,
.react-flow__edge.selectable.selected .react-flow__edge-path {
  stroke: var(--xy-theme-edge-hover);
}
 
.react-flow__handle {
  background-color: var(--xy-handle-background-color-default);
}
 
.react-flow__handle.connectionindicator:hover {
  pointer-events: all;
  border-color: var(--xy-theme-edge-hover);
  background-color: var(--xy-handle-background-color-default);
}
 
.react-flow__handle.connectionindicator:focus,
.react-flow__handle.connectingfrom,
.react-flow__handle.connectingto {
  border-color: var(--xy-theme-edge-hover);
}
 
.react-flow__node-resizer {
  border-radius: 0;
  border: none;
}
 
.react-flow__resize-control.handle {
  background-color: var(--xy-theme-resize-handle-bg);
  border-color: #9e86ed;
  border-radius: 0;
  width: 5px;
  height: 5px;
}
 
/* 
  Custom Example CSS  - This CSS is to improve the example experience.
  You can remove it if you want to use the default styles.
 
  New Theme Classes:
    .xy-theme__button   - Styles for buttons.
    .xy-theme__input    - Styles for text inputs.
    .xy-theme__checkbox - Styles for checkboxes.
    .xy-theme__select   - Styles for dropdown selects.
    .xy-theme__label    - Styles for labels.
  
  Use these classes to apply consistent theming across your components.
*/
 
:root {
  --color-primary: #ff0073;
  --color-background: #fefefe;
  --color-hover-bg: #f6f6f6;
  --color-disabled: #76797e;
}
 
.xy-theme__button-group {
  display: flex;
  align-items: center;
 
  .xy-theme__button:first-child {
    border-radius: 100px 0 0 100px;
  }
 
  .xy-theme__button:last-child {
    border-radius: 0 100px 100px 0;
    margin: 0;
  }
}
 
/* Custom Button Styling */
.xy-theme__button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 2.5rem;
  padding: 0 1rem;
  border-radius: 100px;
  border: 1px solid var(--color-primary);
  background-color: var(--color-background);
  color: var(--color-primary);
  transition:
    background-color 0.2s ease,
    border-color 0.2s ease;
  box-shadow: var(--xy-node-boxshadow-default);
  cursor: pointer;
}
 
.xy-theme__button.active {
  background-color: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}
 
.xy-theme__button.active:hover,
.xy-theme__button.active:active {
  background-color: var(--color-primary);
  opacity: 0.9;
}
 
.xy-theme__button:hover {
  background-color: var(--xy-controls-button-background-color-hover-default);
}
 
.xy-theme__button:active {
  background-color: var(--color-hover-bg);
}
 
.xy-theme__button:disabled {
  color: var(--color-disabled);
  opacity: 0.8;
  cursor: not-allowed;
  border: 1px solid var(--color-disabled);
}
 
.xy-theme__button > span {
  margin-right: 0.2rem;
}
 
/* Add gap between adjacent buttons */
.xy-theme__button + .xy-theme__button {
  margin-left: 0.3rem;
}
 
/* Example Input Styling */
.xy-theme__input {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--color-primary);
  border-radius: 7px;
  background-color: var(--color-background);
  transition:
    background-color 0.2s ease,
    border-color 0.2s ease;
  font-size: 1rem;
  color: var(--xy-theme-panel-text);
}
 
.xy-theme__input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 2px rgba(255, 0, 115, 0.3);
}
 
/* Specific Checkbox Styling */
.xy-theme__checkbox {
  appearance: none;
  -webkit-appearance: none;
  width: 1.25rem;
  height: 1.25rem;
  border-radius: 7px;
  border: 2px solid var(--color-primary);
  background-color: var(--color-background);
  transition:
    background-color 0.2s ease,
    border-color 0.2s ease;
  cursor: pointer;
  display: inline-block;
  vertical-align: middle;
  margin-right: 0.5rem;
}
 
.xy-theme__checkbox:checked {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
}
 
.xy-theme__checkbox:focus {
  outline: none;
  box-shadow: 0 0 0 2px rgba(255, 0, 115, 0.3);
}
 
/* Dropdown Styling */
.xy-theme__select {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--color-primary);
  border-radius: 50px;
  background-color: var(--color-background);
  transition:
    background-color 0.2s ease,
    border-color 0.2s ease;
  font-size: 1rem;
  color: var(--xy-theme-panel-text);
  margin-right: 0.5rem;
  box-shadow: var(--xy-node-boxshadow-default);
}
 
.xy-theme__select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 2px rgba(255, 0, 115, 0.3);
}
 
.xy-theme__label {
  margin-top: 10px;
  margin-bottom: 3px;
  display: inline-block;
  color: var(--xy-theme-panel-text);
}