英文:
when I pass data to a component I get undefined
问题
好的,以下是您要翻译的内容:
"嗯,我在一个Next.js项目中有一个上下文(Context),在那里我处理模态框(modals),我将模态框的详细信息存储在数组(modalBase)中。同时,我从另一个上下文(toolsContext)中获取数据并将其传递给组件。但是,当我在这个上下文中使用console.log输出数据时,它会显示数据,但在将数据传递给组件后,组件中却显示为undefined。我感到困惑。
const [data, setData] = useState();
const [modals, setModals] = useState([]);
const router = useRouter();
const query = router.query;
const { collectionData } = useContext(toolsContext);
useEffect(() => {
const getData = async () => {
const ss = await collectionData(query.taskId);
setData(ss);
};
getData();
}, []);
// ======= 模态框详情
const modalsBase = [
{
name: "collectCreator",
openStatus: false,
content: <CollectionForm />,
},
{
name: "taskItemCreator",
openStatus: false,
content: <TaskItemForm data={data} />,
},
{
name: "taskCreator",
openStatus: false,
content: <TasksForm data={data} />,
},
{
name: "collectionEdit",
openStatus: false,
content: <CollectionEditForm data={data} />,
},
{
name: "taskItemEdit",
openStatus: false,
content: <TaskItemEditForm />,
},
{
name: "tasksEdit",
openStatus: false,
content: <TasksEditForm />,
},
];
我认为我遇到了这个问题是因为我在数组中有组件,并且我尝试将数据传递给这些组件。"
英文:
well,I have Context in nextjs project where I work on modals and I put modal details in the array(modalBase), also I get data from another context(toolsContext) into this context to pass data to components, but When I console data in this context it's given me data but in the components, after passing data to components it gives me undefined, I am confused
const [data, setData] = useState();
const [modals, setModals] = useState([]);
const router = useRouter();
const query = router.query;
const { collectionData } = useContext(toolsContext);
useEffect(() => {
const getData = async () => {
const ss = await collectionData(query.taskId);
setData(ss);
};
getData();
}, []);
// ======= Modal details
const modalsBase = [
{
name: "collectCreator",
openStatus: false,
content: <CollectionForm />,
},
{
name: "taskItemCreator",
openStatus: false,
content: <TaskItemForm data={data} />,
},
{
name: "taskCreator",
openStatus: false,
content: <TasksForm data={data} />,
},
{
name: "collectionEdit",
openStatus: false,
content: <CollectionEditForm data={data} />,
},
{
name: "taskItemEdit",
openStatus: false,
content: <TaskItemEditForm />,
},
{
name: "tasksEdit",
openStatus: false,
content: <TasksEditForm />,
},
];
I think that I get this problem because I have components in the array and I try to pass data to components
答案1
得分: 1
The data
is undefined in your components because you're initializing it asynchronously in a useEffect
hook, and then immediately using it in your modalsBase
array. Remember that useEffect
is executed after the component render, and fetching the data is also an asynchronous operation.
This means that when your modalsBase
array is being defined, data
is still undefined
. It only gets a value after the data fetching has completed, and by this time, your modalsBase
array has already been defined with undefined
data.
To fix this issue, you should move your modalsBase
array inside a useEffect
hook that has data
as a dependency. This way, the array will be redefined every time data
changes. Here's how you can do it:
const [modals, setModals] = useState([]);
useEffect(() => {
const modalsBase = [
{
name: "collectCreator",
openStatus: false,
content: <CollectionForm />,
},
{
name: "taskItemCreator",
openStatus: false,
content: <TaskItemForm data={data} />,
},
// ...
];
setModals(modalsBase);
}, [data]);
Now, modalsBase
is redefined every time data
changes, which includes the initial fetch. The components will receive the updated data
correctly.
Also, I recommend initializing data
as null
instead of undefined
to make it more explicit that it is intentionally empty at the start. That way, you can use conditionals to render different things based on whether data
is null
or has a value. You can do this by changing the line const [data, setData] = useState();
to const [data, setData] = useState(null);
.
Remember that this will cause a re-render every time data
changes. If data
changes frequently, you might want to consider a different approach, such as passing a loading state to the components, or fetching the data inside the components themselves.
英文:
The data
is undefined in your components because you're initializing it asynchronously in a useEffect
hook, and then immediately using it in your modalsBase
array. Remember that useEffect
is executed after the component render, and fetching the data is also an asynchronous operation.
This means that when your modalsBase
array is being defined, data
is still undefined
. It only gets a value after the data fetching has completed, and by this time, your modalsBase
array has already been defined with undefined
data.
To fix this issue, you should move your modalsBase
array inside a useEffect
hook that has data
as a dependency. This way, the array will be redefined every time data
changes. Here's how you can do it:
const [modals, setModals] = useState([]);
useEffect(() => {
const modalsBase = [
{
name: "collectCreator",
openStatus: false,
content: <CollectionForm />,
},
{
name: "taskItemCreator",
openStatus: false,
content: <TaskItemForm data={data} />,
},
// ...
];
setModals(modalsBase);
}, [data]);
Now, modalsBase
is redefined every time data
changes, which includes the initial fetch. The components will receive the updated data
correctly.
Also, I recommend initializing data
as null
instead of undefined
to make it more explicit that it is intentionally empty at the start. That way, you can use conditionals to render different things based on whether data
is null
or has a value. You can do this by changing the line const [data, setData] = useState();
to const [data, setData] = useState(null);
.
Remember that this will cause a re-render every time data
changes. If data
changes frequently, you might want to consider a different approach, such as passing a loading state to the components, or fetching the data inside the components themselves.
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