Inside reducer, given a state object:
var state = {
"data": [{
"subset": [{
"id": 1
}, {
"id": 2
}]
}, {
"subset": [{
"id": 10
}, {
"id": 11
}, {
"id": 12
}]
}]
}
As you can see, the data is a nested array, with arrays in each of its elements.
Knowning that action.indexToUpdate will be a index for data, I want to update data[action.indexToUpdate].subset to a new array programmatically. For example, if action.indexToUpdate = 0, then data[0] will be updated from
[{"id":1},{"id":2}]
to
[{"id":4},{"id":5}]
In order to do so, I have:
let newSubset = [{"id":4},{"id":5}]
let newState = update(state.data[action.indexToUpdate], {
subset: {
newSubset,
},
})
But when I executed this, it returns error:
TypeError: value is undefined
on the update founction.
I have been looking at the react ducomentation here: https://facebook.github.io/react/docs/update.html but I couldn't really figure out how to do it. Please advise!
Your update will look like
var obj = {"state" : {
"data": [{
"subset": [{
"id": 1
}, {
"id": 2
}]
}, {
"subset": [{
"id": 10
}, {
"id": 11
}, {
"id": 12
}]
}]
}}
return update(obj, {
"state" : {
"data": {
[action.indexToUpdate]: {
"subset": {
$set: [newSubset]
}
}
}
}
})
In case there are other fields in subset, but you only wish to the change the fields at specific index containing other keys, you would write
return update(obj, {
"state" : {
"data": {
[action.indexToUpdate]: {
"subset": {
[id]: {$merge: newSubset}
}
}
}
}
})