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reactjstypescriptreact-lifecycle

Set object values of state using setState method


I have an object as a state variable in React. I want to change its various value using the setState method but it shows. Although I am able to set it using this.state method but this is not the right way I guess.

How can I do this?


 this.state={
            graphData:{
                labels:['4 P.M','5 P.M','6 P.M','7 P.M','8 P.M','9 P.M','10 P.M','11 P.M','12 A.M','1 A.M','2 A.M','3 A.M','4 A.M'],
                datasets:[
                    {
                    label:"Day",
                    backgroundColor:"#F6ABE4",
                    borderColor:'#333',
                    borderWidth:2,
                    lineTension:0.1,
                    fill:true,
                    data:[4,5,6,7,8,9,10,11,12,1,2,3,4]
            
                    }
            
            
                ]
            }
}

 this.setState({[graphData.datasets[0].backgroundColor]:"#F6ABE4"})


this.setState((state) => ({
                    graphData : {
                        ...state.graphData ,
                        datasets : [
                
                            // First slice of array before the index we want to change
                            ...state.graphData.datasets.slice(0, 5),
                
                            // changing the element on the given index
                            {
                                ...state.graphData.datasets[0] ,
                                // you can modify all the properties you want
                                data : result // <------ CHANGE HERE
                            },
                
                            // rest of the array elements after index
                            ...state.graphData.datasets.slice(6+1)
                        ]
                    }
                }))


Solution

  • Here you go, you can do something like this :

    this.setState((state) => ({
        graphData : {
            ...state.graphData ,
            datasets : [
    
                // First slice of array before the index we want to change
                ...state.graphData.datasets.slice(0, index),
    
                // changing the element on the given index
                {
                    ...state.graphData.datasets[index] ,
                    // you can modify all the properties you want
                    backgroundColor : "#F6ABE4" // <------ CHANGE HERE
                },
    
                // rest of the array elements after index
                ...state.graphData.datasets.slice(index+1)
            ]
        }
    }))
    

    Hope the code comments will clear the doubts