:::demo A node's data is not fetched until it is clicked, so the Tree cannot predict whether a node is a leaf node. That's why a drop-down button is added to each node, and if it is a leaf node, the drop-down button will disappear when clicked. That being said, you can also tell the Tree in advance whether the node is a leaf node, avoiding the render of the drop-down button before a leaf node.
```html
<el-tree
:props="props"
:load="loadNode"
lazy
show-checkbox>
</el-tree>
<script>
export default {
data() {
return {
props: {
label: 'name',
children: 'zones',
isLeaf: 'leaf'
},
};
},
methods: {
loadNode(node, resolve) {
if (node.level === 0) {
return resolve([{ name: 'region' }]);
}
if (node.level > 1) return resolve([]);
setTimeout(() => {
const data = [{
name: 'leaf',
leaf: true
}, {
name: 'zone'
}];
resolve(data);
}, 500);
}
}
};
</script>
```
:::
### Disabled checkbox
The checkbox of a node can be set as disabled.
:::demo In the example, 'disabled' property is declared in defaultProps, and some nodes are set as 'disabled:true'. The corresponding checkboxes are disabled and can't be clicked.
:::demo Use `default-expanded-keys` and `default-checked-keys` to set initially expanded and initially checked nodes respectively. Note that for them to work, `node-key` is required. Its value is the name of a key in the data object, and the value of that key should be unique across the whole tree.
```html
<el-tree
:data="data"
show-checkbox
node-key="id"
:default-expanded-keys="[2, 3]"
:default-checked-keys="[5]"
:props="defaultProps">
</el-tree>
<script>
export default {
data() {
return {
data: [{
id: 1,
label: 'Level one 1',
children: [{
id: 4,
label: 'Level two 1-1',
children: [{
id: 9,
label: 'Level three 1-1-1'
}, {
id: 10,
label: 'Level three 1-1-2'
}]
}]
}, {
id: 2,
label: 'Level one 2',
children: [{
id: 5,
label: 'Level two 2-1'
}, {
id: 6,
label: 'Level two 2-2'
}]
}, {
id: 3,
label: 'Level one 3',
children: [{
id: 7,
label: 'Level two 3-1'
}, {
id: 8,
label: 'Level two 3-2'
}]
}],
defaultProps: {
children: 'children',
label: 'label'
}
};
}
};
</script>
```
:::
### Checking tree nodes
:::demo This example shows how to get and set checked nodes. They both can be done in two approaches: node and key. If you are taking the key approach, `node-key` is required.
```html
<el-tree
:data="data"
show-checkbox
default-expand-all
node-key="id"
ref="tree"
highlight-current
:props="defaultProps">
</el-tree>
<divclass="buttons">
<el-button@click="getCheckedNodes">get by node</el-button>
<el-button@click="getCheckedKeys">get by key</el-button>
<el-button@click="setCheckedNodes">set by node</el-button>
<el-button@click="setCheckedKeys">set by key</el-button>
<el-button@click="resetChecked">reset</el-button>
</div>
<script>
export default {
methods: {
getCheckedNodes() {
console.log(this.$refs.tree.getCheckedNodes());
},
getCheckedKeys() {
console.log(this.$refs.tree.getCheckedKeys());
},
setCheckedNodes() {
this.$refs.tree.setCheckedNodes([{
id: 5,
label: 'Level two 2-1'
}, {
id: 9,
label: 'Level three 1-1-1'
}]);
},
setCheckedKeys() {
this.$refs.tree.setCheckedKeys([3]);
},
resetChecked() {
this.$refs.tree.setCheckedKeys([]);
}
},
data() {
return {
data: [{
id: 1,
label: 'Level one 1',
children: [{
id: 4,
label: 'Level two 1-1',
children: [{
id: 9,
label: 'Level three 1-1-1'
}, {
id: 10,
label: 'Level three 1-1-2'
}]
}]
}, {
id: 2,
label: 'Level one 2',
children: [{
id: 5,
label: 'Level two 2-1'
}, {
id: 6,
label: 'Level two 2-2'
}]
}, {
id: 3,
label: 'Level one 3',
children: [{
id: 7,
label: 'Level two 3-1'
}, {
id: 8,
label: 'Level two 3-2'
}]
}],
defaultProps: {
children: 'children',
label: 'label'
}
};
}
};
</script>
```
:::
### Custom node content
The content of tree nodes can be customized, so you can add icons or buttons as you will
:::demo There are two ways to customize template for tree nodes: `render-content` and scoped slot. Use `render-content` to assign a render function that returns the content of tree nodes. See Vue's documentation for a detailed introduction of render functions. If you prefer scoped slot, you'll have access to `node` and `data` in the scope, standing for the TreeNode object and node data of the current node respectively. Note that the `render-content` demo can't run in jsfiddle because it doesn't support JSX syntax. In a real project, `render-content` will work if relevant dependencies are correctly configured.
:::demo Invoke the `filter` method of the Tree instance to filter tree nodes. Its parameter is the filtering keyword. Note that for it to work, `filter-node-method` is required, and its value is the filtering method.
```html
<el-input
placeholder="Filter keyword"
v-model="filterText">
</el-input>
<el-tree
class="filter-tree"
:data="data"
:props="defaultProps"
default-expand-all
:filter-node-method="filterNode"
ref="tree">
</el-tree>
<script>
export default {
watch: {
filterText(val) {
this.$refs.tree.filter(val);
}
},
methods: {
filterNode(value, data) {
if (!value) return true;
return data.label.indexOf(value) !== -1;
}
},
data() {
return {
filterText: '',
data: [{
id: 1,
label: 'Level one 1',
children: [{
id: 4,
label: 'Level two 1-1',
children: [{
id: 9,
label: 'Level three 1-1-1'
}, {
id: 10,
label: 'Level three 1-1-2'
}]
}]
}, {
id: 2,
label: 'Level one 2',
children: [{
id: 5,
label: 'Level two 2-1'
}, {
id: 6,
label: 'Level two 2-2'
}]
}, {
id: 3,
label: 'Level one 3',
children: [{
id: 7,
label: 'Level two 3-1'
}, {
id: 8,
label: 'Level two 3-2'
}]
}],
defaultProps: {
children: 'children',
label: 'label'
}
};
}
};
</script>
```
:::
### Accordion
Only one node among the same level can be expanded at one time.
:::demo
```html
<el-tree
:data="data"
:props="defaultProps"
accordion
@node-click="handleNodeClick">
</el-tree>
<script>
export default {
data() {
return {
data: [{
label: 'Level one 1',
children: [{
label: 'Level two 1-1',
children: [{
label: 'Level three 1-1-1'
}]
}]
}, {
label: 'Level one 2',
children: [{
label: 'Level two 2-1',
children: [{
label: 'Level three 2-1-1'
}]
}, {
label: 'Level two 2-2',
children: [{
label: 'Level three 2-2-1'
}]
}]
}, {
label: 'Level one 3',
children: [{
label: 'Level two 3-1',
children: [{
label: 'Level three 3-1-1'
}]
}, {
label: 'Level two 3-2',
children: [{
label: 'Level three 3-2-1'
}]
}]
}],
defaultProps: {
children: 'children',
label: 'label'
}
};
},
methods: {
handleNodeClick(data) {
console.log(data);
}
}
};
</script>
```
:::
### Draggable
You can drag and drop Tree nodes by adding a `draggable` attribute.
| highlight-current | whether current node is highlighted | boolean | — | false |
| default-expand-all | whether to expand all nodes by default | boolean | — | false |
| expand-on-click-node | whether to expand or collapse node when clicking on the node, if false, then expand or collapse node only when clicking on the arrow icon. | boolean | — | true |
| check-on-click-node | whether to check or uncheck node when clicking on the node, if false, the node can only be checked or unchecked by clicking on the checkbox. | boolean | — | false |
| auto-expand-parent | whether to expand father node when a child node is expanded | boolean | — | true |
| default-expanded-keys | array of keys of initially expanded nodes | array | — | — |
| check-strictly | whether checked state of a node not affects its father and child nodes when `show-checkbox` is `true` | boolean | — | false |
| default-checked-keys | array of keys of initially checked nodes | array | — | — |
| current-node-key | key of initially selected node | string, number | — | — |
| filter-node-method | this function will be executed on each node when use filter method. if return `false`, tree node will be hidden. | Function(value, data, node) | — | — |
| accordion | whether only one node among the same level can be expanded at one time | boolean | — | false |
| indent | horizontal indentation of nodes in adjacent levels in pixels | number | — | 16 |
| lazy | whether to lazy load leaf node, used with `load` attribute | boolean | — | false |
| draggable | whether enable tree nodes drag and drop | boolean | — | false |
| allow-drag | this function will be executed before dragging a node. If `false` is returned, the node can not be dragged | Function(node) | — | — |
| allow-drop | this function will be executed before the dragging node is dropped. If `false` is returned, the dragging node can not be dropped at the target node. `type` has three possible values: 'prev' (inserting the dragging node before the target node), 'inner' (inserting the dragging node to the target node) and 'next' (inserting the dragging node after the target node) | Function(draggingNode, dropNode, type) | — | — |
| filter | filter all tree nodes, filtered nodes will be hidden | Accept a parameter which will be used as first parameter for filter-node-method |
| updateKeyChildren | set new data to node, only works when `node-key` is assigned | (key, data) Accept two parameters: 1. key of node 2. new data |
| getCheckedNodes | If the node can be selected (`show-checkbox` is `true`), it returns the currently selected array of nodes | (leafOnly, includeHalfChecked) Accept two boolean type parameters: 1. default value is `false`. If the parameter is `true`, it only returns the currently selected array of sub-nodes. 2. default value is `false`. If the parameter is `true`, the return value contains halfchecked nodes |
| setCheckedNodes | set certain nodes to be checked, only works when `node-key` is assigned | an array of nodes to be checked |
| getCheckedKeys | If the node can be selected (`show-checkbox` is `true`), it returns the currently selected array of node's keys | (leafOnly) Accept a boolean type parameter whose default value is `false`. If the parameter is `true`, it only returns the currently selected array of sub-nodes. |
| setCheckedKeys | set certain nodes to be checked, only works when `node-key` is assigned | (keys, leafOnly) Accept two parameters: 1. an array of node's keys to be checked 2. a boolean type parameter whose default value is `false`. If the parameter is `true`, it only returns the currently selected array of sub-nodes. |
| setChecked | set node to be checked or not, only works when `node-key` is assigned | (key/data, checked, deep) Accept three parameters: 1. node's key or data to be checked 2. a boolean typed parameter indicating checked or not. 3. a boolean typed parameter indicating deep or not. |
| getHalfCheckedNodes | If the node can be selected (`show-checkbox` is `true`), it returns the currently half selected array of nodes | - |
| getHalfCheckedKeys | If the node can be selected (`show-checkbox` is `true`), it returns the currently half selected array of node's keys | - |
| getCurrentKey | return the highlight node's key (null if no node is highlighted) | — |
| getCurrentNode | return the highlight node's data (null if no node is highlighted) | — |
| setCurrentKey | set highlighted node by key, only works when `node-key` is assigned | (key, shouldAutoExpandParent=true) 1. the node's key to be highlighted. If `null`, cancel the currently highlighted node 2. whether to automatically expand parent node |
| setCurrentNode | set highlighted node, only works when `node-key` is assigned | (node, shouldAutoExpandParent=true) 1. the node to be highlighted 2. whether to automatically expand parent node |
| getNode | get node by data or key | (data) the node's data or key |
| remove | remove a node, only works when node-key is assigned | (data) the node's data or node to be deleted |
| append | append a child node to a given node in the tree | (data, parentNode) 1. child node's data to be appended 2. parent node's data, key or node |
| insertBefore | insert a node before a given node in the tree | (data, refNode) 1. node's data to be inserted 2. reference node's data, key or node |
| insertAfter | insert a node after a given node in the tree | (data, refNode) 1. node's data to be inserted 2. reference node's data, key or node |
| node-click | triggers when a node is clicked | three parameters: node object corresponding to the node clicked, `node` property of TreeNode, TreeNode itself |
| node-contextmenu | triggers when a node is clicked by right button | four parameters: event, node object corresponding to the node clicked, `node` property of TreeNode, TreeNode itself |
| check-change | triggers when the selected state of the node changes | three parameters: node object corresponding to the node whose selected state is changed, whether the node is selected, whether node's subtree has selected nodes |
| check | triggers after clicking the checkbox of a node | two parameters: node object corresponding to the node that is checked / unchecked, tree checked status object which has four props: checkedNodes, checkedKeys, halfCheckedNodes, halfCheckedKeys |
| current-change | triggers when current node changes | two parameters: node object corresponding to the current node, `node` property of TreeNode |
| node-expand | triggers when current node open | three parameters: node object corresponding to the node opened, `node` property of TreeNode, TreeNode itself |
| node-collapse | triggers when current node close | three parameters: node object corresponding to the node closed, `node` property of TreeNode, TreeNode itself |
| node-drag-start | triggers when dragging starts | two parameters: node object corresponding to the dragging node, event. |
| node-drag-enter | triggers when the dragging node enters another node | three parameters: node object corresponding to the dragging node, node object corresponding to the entering node, event. |
| node-drag-leave | triggers when the dragging node leaves a node | three parameters: node object corresponding to the dragging node, node object corresponding to the leaving node, event. |
| node-drag-over | triggers when dragging over a node (like mouseover event) | three parameters: node object corresponding to the dragging node, node object corresponding to the dragging over node, event. |
| node-drag-end | triggers when dragging ends | four parameters: node object corresponding to the dragging node, node object corresponding to the dragging end node (may be `undefined`), node drop type (before / after / inner), event. |
| node-drop | triggers after the dragging node is dropped | four parameters: node object corresponding to the dragging node, node object corresponding to the dropped node, node drop type (before / after / inner), event. |
