getting unique objects from array of nested object and sub properties

Question

i have a script where i am trying to get the unique object based on state from the array of objects

The below scripts works fine, but I have one case where I have nested object in one kind of state has a sub-state, so I want to find the unique from the array of objects and get the unique.

The below snippet I am able to get the first level, but if we see the state => "EF" has a sub_state_details, so I need to get the unique from sub_state_details if state is EF

let inputArray = [{
    state: "AB",
  }, {
    state: "BC",
  }, {
    state: "BC",
  }, {
    state: "CD",
  }, {
    state: "CD",
  }, {
    state: "DE",
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  },
  {
    state: "EF",
    sub_state_details: {
      state: "EF-2"
    }
  }
]

let resArr = []
inputArray.filter(function(item) {
  var i = resArr.findIndex(x => (x.state == item.state));
  if (i <= -1) {
    resArr.push({
      state: item.state
    });
  }
  return null;
});

console.log(resArr)

expected output

let output = [{
      state: "AB",
    }, {
      state: "BC",
    }, {
      state: "CD",
    }, {
      state: "DE",
    }, {
      state: "EF-1",
    },{
      state: "EF-2",
    }]

andy mccullough · Accepted Answer · 2021-12-23 06:40:41Z

2

Other answers may give you the correct result, but they are using array functions incorrectly, granted they are based on your attempt. e.g. some using filter but never using the result from the filter. or trying to return null from a forEach even though forEach doesn't. return anything

reduce() is better suited to your case, as you are reducing one array to another, based on some conditions -

let inputArray = [{
    state: "AB",
  }, {
    state: "BC",
  }, {
    state: "BC",
  }, {
    state: "CD",
  }, {
    state: "CD",
  }, {
    state: "DE",
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  },
  {
    state: "EF",
    sub_state_details: {
      state: "EF-2"
    }
  }
]

const result = inputArray.reduce((acc, cur) => {
  if(!acc.find((accItem) => accItem.state == cur.state)) {
    if(cur.state === 'EF') {
       if(cur.sub_state_details && !acc.find((accItem) => accItem.state === cur.sub_state_details.state)) {
          acc.push({state: cur.sub_state_details.state})
       }
    } else {
       acc.push({state: cur.state})
    }
    
  }
  return acc;
}, [])

console.log(result)

edited Dec 23, 2021 at 6:40

answered Dec 23, 2021 at 6:19

andy mccullough

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4 Comments

Plutus Over a year ago

you have added if(cur.state == 'EF') in the if condition, this is specific to 'EF' right, if state AB have substate. How it will behave?. We need to add one more condition in if statement

andy mccullough Over a year ago

The question says - "The below snippet I am able to get the first level, but if we see the state => "EF" has a sub_state_details, so I need to get the unique from sub_state_details if state is EF"

Battledash2 Over a year ago

But there are two EF-1s, only one is showing?

andy mccullough Over a year ago

@Battledoosh look at the expected output in the OP, that's the expected behaviour

programandoconro · Accepted Answer · 2021-12-23 06:06:13Z

You can use a conditional statement to check if sub_state_details exists.

Like this:

let inputArray = [
  {
state: "AB",
  },
  {
state: "BC",
  },
  {
state: "BC",
  },
  {
state: "CD",
  },
  {
state: "CD",
  },
  {
state: "DE",
  },
  {
state: "EF",
sub_state_details: {
  state: "EF-1",
},
  },
  {
state: "EF",
sub_state_details: {
  state: "EF-1",
},
  },
  {
state: "EF",
sub_state_details: {
  state: "EF-2",
},
  },
];

let resArr = [];
inputArray.filter(function (item) {
  var i = resArr.findIndex((x) => x.state == item.state);
  if (i <= -1) {
if (item.sub_state_details) {
  resArr.push({
    state: item.sub_state_details.state,
  });
} else {
  resArr.push({
    state: item.state,
  });
}
  }
  return null;
});

console.log(resArr);

Battledash2 · Accepted Answer · 2021-12-23 06:05:42Z

-1

This is actually a pretty simple solution. You first have to check if sub_state_details exists. If it does, we need to use that state instead. We can achieve this by using a variable called "sub," and if the sub_state_details object is defined, we use sub_state_details.state instead of item.state.

let inputArray = [{
    state: "AB",
  }, {
    state: "BC",
  }, {
    state: "BC",
  }, {
    state: "CD",
  }, {
    state: "CD",
  }, {
    state: "DE",
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  },
  {
    state: "EF",
    sub_state_details: {
      state: "EF-2"
    }
  }
]

let resArr = []
inputArray.filter(function(item) {
  var i = resArr.findIndex(x => (x.state == item.state));
  let sub = item.sub_state_details;
  if(!sub) {sub=item}
  if (i <= -1) {
    resArr.push({
      state: sub.state
    });
  }
  return null;
});

console.log(resArr)

Hope I could help.

answered Dec 23, 2021 at 6:05

Battledash2

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1 Comment

Battledash2 Over a year ago

Gosh, I was just trying to help. What's the point of the -1?

Plutus · Accepted Answer · 2021-12-23 06:56:35Z

-1

I have rewritten your code with some minor changes, that will solve your problem. Instead of checking only state, in the findIndex function, I have included one more condition for sub_state_details also if its present.

No need to worry about state & its sub-state, try code

var i = resArr.findIndex(x => 
  {
    return (x.state === item.state && ((x.sub_state_details && x.sub_state_details.state) ? x.sub_state_details.state === item.sub_state_details.state : true))
  });

Instead of directly pushing into the empty, check the array has sub-state details, push along with the array. Already we checked the state & substate are unique.

if(item.sub_state_details) {
      resArr.push({
        state: item.state,
        sub_state_details: item.sub_state_details
      });
    }

let inputArray = [{
    state: "AB",
  }, {
    state: "BC",
  }, {
    state: "BC",
  }, {
    state: "CD",
  }, {
    state: "CD",
  }, {
    state: "DE",
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  }, {
    state: "EF",
    sub_state_details: {
      state: "EF-1"
    }
  },
  {
    state: "EF",
    sub_state_details: {
      state: "EF-2"
    }
  }
]

let resArr = []
inputArray.filter(function(item) {
  var i = resArr.findIndex(x => 
  {
    return (x.state === item.state && ((x.sub_state_details && x.sub_state_details.state) ? x.sub_state_details.state === item.sub_state_details.state : true))
  });
  if (i <= -1) {
    if(item.sub_state_details) {
      resArr.push({
        state: item.state,
        sub_state_details: item.sub_state_details
      });
    }
    else {
      resArr.push({
        state: item.state,
      });
    }
  }
  return null;
});

console.log(resArr);

I hope this would be useful.

answered Dec 23, 2021 at 6:56

Plutus

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2 Comments

andy mccullough Over a year ago

your output does not match the expected output, and why are you using filter() when you dont do anything with the result from filter() ?

Battledash2 Over a year ago

What makes this different then just straight up console.logging the entire object?

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