React native get a specific element value from state array - arrays

Question

I am new to React-Native i am building a sample app, But i ha d small problem with this.state.array , I want a particular element value from array
my array is
this.state.userDetail: [
Object {
"creation_Date": "2019-10-22T06:34:52.000Z",
"mobile": 9985849955,
"name": "siva",
"password": "123456",
"picture_url": "5.jpg",
"role": "",
"user_id": 1,
},
]
````````````````````````````````````````
In the above array i want user_id value ,
i tried different methods like
```````````````````````````
this.setState({ user_id: this.state.user_Details.user_id })
const item_id = this.state.user_Details.map((item) => { item.user_id });
var item_id = this.state.user_Details.filter(userDetails => { return userDetails[7]; })
``````````````````````````````````````````
but nothing will work i want only user_id value to update the users table , So please any help ..

Answer 1

If you wish to extract the user_id SPECIFICALLY from this example:
[
{
"creation_Date": "2019-10-22T06:34:52.000Z",
"mobile": 9985849955,
"name": "siva",
"password": "123456",
"picture_url": "5.jpg",
"role": "",
"user_id": 1,
},
]
and assuming this data is in your this.state.userDetail property.
The only thing you need is:
this.state.userDetail[0].user_id
Why this might not be working for you:
this.state.userDetail: [
Object { /// What's Object?
And if you are trying to parse more than 1 entry in the array unlike your example, you first need to select a certain entry with a 'for' loop or a .map() function.

Answer 2

I think you want to get one index user id, so I give the following code:
// define it in the constructor, and it may have more than one items
this.state.userDetail: [
{
"creation_Date": "2019-10-22T06:34:52.000Z",
"mobile": 9985849955,
"name": "siva",
"password": "123456",
"picture_url": "5.jpg",
"role": "",
"user_id": 1,
},
]
// do not directly assign use this.state.x
let copyUserDetails = {...this.this.state.user_Details}
let userIdsArray = copyUserDetail.map((item) => { return item.user_id });
let itemId = userIdsArray[0]
console.log("the first user Id is",itemId)
// if you only want to the user_id, you can directly copyUserDetails[0].user_id
let userId = copyUserDetails[0].user_id
console.log("the first user Id is ==> ",userId)
this.setState({ user_id: itemID })
// the filter is accordng some condtion to return a new arry
let itemFilterArray = copyUserDetails.filter((element,i) => {
// filter the item which match some condition, for example the uerId not equal
//0
if(element.user_id !== 0){
return element
}
})
according to your require, I give the following code:
//if you do not have many userInfo
constructor(props){
super(props)
this.state= {
user_Details: {
"creation_Date": "2019-10-22T06:34:52.000Z",
"mobile": 9985849955,
"name": "siva",
"password": "123456",
"picture_url": "5.jpg",
"role": "",
"user_id": 1,
}
}
// somewhere you want the userId
getUserId = () => {
return this.state.user_Details.user_id
}
}
//if you have many userinfo
constructor(props){
super(props)
this.state= {
user_Details: [{
"creation_Date": "2019-10-22T06:34:52.000Z",
"mobile": 9985849955,
"name": "siva",
"password": "123456",
"picture_url": "5.jpg",
"role": "",
"user_id": 1,
}]
}
// somewhere you want the some index userId
getUserId = (index) => {
// do not directly assign use this.state.x
let copyUserDetails = {...this.this.state.user_Details}
return copyUserDetails[index].user_id
}
//somwhere you want all the userId
getUserId = () => {
// do not directly assign use this.state.x
let copyUserDetails = {...this.this.state.user_Details}
let userIdArray = copyUserDetail.map((item) => { return item.user_id });
return userIdArray
}
}
and I suggest you can read the api about json and array