Question

我有一个react组件，并且在那个react组件中，我正在使用blueprint.js Tree fucntion根据服务器返回的json对象渲染树。我遇到了我要修复的类型问题，但是我不确定它来自哪里...这是错误：

Type 'ITreeNode<{}>[] | undefined' is not assignable to type 'ITreeNode<{}>[]'.
  Type 'undefined' is not assignable to type 'ITreeNode<{}>[]'.ts(2322)
HelpTree.tsx(11, 5): The expected type comes from property 'nodes' which is declared here on type 'IntrinsicAttributes & IntrinsicClassAttributes<HelpTree> & Readonly<State> & Readonly<{ children?: ReactNode; }>'

我不确定为什么会收到此错误或如何解决该错误。

这是源代码。我正在使用bluepring中的Tree，并且在动态构建ITreeNode之后对其进行分配。

export const HelpDialog: React.FC = () => {
    const themeClass = useBehavior(mainStore.themeClass);
    const isOpen = useBehavior(mainStore.isHelpDialogVisible);

    const [files, setFiles] = useState([]);

    const [folderLoading, setFolderLoading] = useState(false);

    const InitialState: ITreeNode[] = [];

    let currentNode: HelpDTO;
    let parentFolder: any = {};
    let majorFolder: any = {};
    let majorFile: any = {};

    useEffect(() => {
        if (isOpen) {
            fetchHelp();
        }
    }, [isOpen]);

    const fetchHelp = () => {
        helpApi.getHelpFiles().then((response) => {
            if (response.status !== 200) return;
            setFiles(response.data);
            checkFileContent();
        });
    };

    return (
        <Dialog
            className={classNames(themeClass, styles.helpDialog)}
            title="Help"
            icon="help"
            isOpen={isOpen}
            onOpened={fetchHelp}
            onClose={closeDialogBox}
        >
            <div style={{ overflowY: "scroll" }}>
                {folderLoading ? <HelpTree nodes={setNodes(files)} /> : <Spinner />}
            </div>
        </Dialog>
    );
};

错误从最后一行的第5条开始出现：

{folderLoading ? <HelpTree nodes={setNodes(files)} /> :

贴花节点：

这是树的声明位置：

interface Props {
    nodes: ITreeNode[];
}

export interface State {
    nodes: ITreeNode[];
}

// use Component so it re-renders everytime: `nodes` are not a primitive type
// and therefore aren't included in shallow prop comparison
export class HelpTree extends React.Component<State, Props> {
    constructor(props: Props) {
        super(props);
        this.state = {
            nodes: props.nodes
        };
    }

    render() {
        return (
            <Tree
                contents={this.state.nodes}
                onNodeCollapse={this.handleNodeCollapse}
                onNodeExpand={this.handleNodeExpand}
                onNodeDoubleClick={this.handleNodeDoubleClick}
            />
        );
    }
}

Answer 1

错误告诉您setNodes函数可能返回"undefined"而不是ITreeNode。

您可以通过替换以下内容来更改声明树的类型：

interface Props {
    nodes: ITreeNode[];
}

与此：

interface Props {
    nodes: ITreeNode[] | undefined;
}

或者您可以检查setNodes以确保它永远不会返回"undefined"

typescrpt错误：键入'ITreeNode <{}> [] |未定义”不能分配给类型“ ITreeNode <{}> []”

1 个答案: