I need to update some keys of a nested object, but whether or not each key is updated comes with some if condition.
Currently I am using lodash cloneDeep()
like below ... which works fine, but I want to improve on performance so i want to use immutability-helper
library instead.
state = {
info : {
xyz : {
name : {
first : '',
last : '',
},
age : '',
}
}
}
let newInfo = _.cloneDeep(this.state.info);
if (some condition)
newInfo.xyz.name.first = 'iron'
if (some condition)
newInfo.xyz.name.last = 'man'
if (some condition)
newInfo.xyz.age = 50
this.setState({ info : newInfo});
But the problem is that the immutability helper sort of requires all changes in one update call. So either i put all these if conditions inside the update call. I dont even know how to do that, and even if i do, that will make the code very unreadable if i have many conditions and many keys to update.
Or create multiple copies (1 for each change) and merge them later somehow ???
import update from 'immutability-helper';
if (some condition)
newInfo_1 = update(this.state.info, {xyz: {name: {first: {$set: 'iron' }}}} )
if (some condition)
newInfo_2 = update(this.state.info, {xyz: {name: {last: {$set: 'man' }}}} )
if (some condition)
newInfo_3 = update(this.state.info, {xyz: {age: {$set: 50 }}} )
// do i merge the newInfo_1, _2 & _3 somehow ????
// this.setState({ info : ????? })
Is there a correct way to do conditional updates with immutability-helper ?
You can use the $apply
command to conditionally apply changes. It takes a function as argument, and passes the current value to the function. So, you could do something like this:
const condition1 = true;
const condition2 = true;
const condition3 = false;
const updatedInfo = update(this.state.info, {
xyz: {
name: {
first: {
$apply: current => condition1 ? 'iron' : current
},
last: {
$apply: current => condition2 ? 'man' : current
}
},
age: {
$apply: current => condition3 ? 50 : current
}
}
})
The command also comes with a shorthand, so you can pass the function directly, like this:
first: current => condition1 ? "iron" : current,