Read a value key of a JSON constant in Typescript with Angular

Question

I'm trying to read a value in a JSON constant in Typescript with Angular, but just for performance I don't know if there is a way to read with a property included in the framework (or if it exists another way to do better, of course). This is my JSON constant value:

    const myConstant= {
    data : [
      {
          key1: "5",
          key2: "extract",
          key3: "unique1"
      },
      {
          key1: "5",
          key2: "extract",
          key3: "unique2"
      },
      {
        key1: "5",
          key2: "extract",
          key3: "unique3"
    }
  ]
  };

This constant has exported in another TS file just for find the key3 value for validate this in a conditional.

 validateInfo(cod:string){
    for (var i = 0; i < myConstant.data.length; i++){
      var obj = myConstant.data[i];
      for (var key in obj){
        var value = obj[key];
        if (key== "key3"){
          if (value == cod){
            return true;
          }
        }
      }
    }
    return false;
  }

So my question is, There is a way to extract the "key3" Value without doing a loop? like

myConstant.find(data.key3,'unique3');

what is the reason? I am trying to hide a view in frontend in case an user has no allowed to access using the JSON info (true or false for the previous function):

<div class="ts-cntnr" *ngIf="allowedInfo" >

Deepak · Accepted Answer · 2021-12-20 18:18:19Z

2

Obviously there is! There are many ways you can do what you are asking for, and a simpler one is to use some() which checks if there is at least one object with a key called key3, returning a boolean result which is your desired output.

const myConstant = {
  data: [{
      key1: "5",
      key2: "extract",
      key3: "unique1"
    },
    {
      key1: "5",
      key2: "extract",
      key3: "unique2"
    },
    {
      key1: "5",
      key2: "extract",
      key3: "unique3"
    }
  ]
};

console.log(myConstant.data.some(subData => Object.keys(subData).includes("key3")))

// UPDATE
console.log(myConstant.data.some(subData => Object.keys(subData).includes("key3") && subData["key3"] == "unique3"))

edited Dec 20, 2021 at 18:18

answered Dec 20, 2021 at 17:17

Deepak

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6 Comments

realjohnhudson Over a year ago

It's a good code, but the real purpose that I need is check in the JSON the value for key3. ie, I want to compare the incoming value (from "cod" param) and check if in the JSON exists that code (verify if unique3 is in the list)

Deepak Over a year ago

Ahh no change required still. Just add that comparison you asked for :) I've updated the code.

realjohnhudson Over a year ago

oh thanks, it looks great. but now I have a problem, when I try to compile the IDE shows me this error "This condition will always return 'false' since the types 'number' and 'string' have no overlap." in the updated part. So I partitioned that in a clean JSON. but when I set subData.key3["key3"] it shows me undefined. I don't know if it is a JSON restriction or I need to do something aditional.

Deepak Over a year ago

I see. I'm not sure what interface type you use for your original data. Can you try replacing the updated part of my code with this: console.log(myConstant.data.some((subData: { [x: string]: string; }) => Object.keys(subData).includes("key3") && subData["key3"] == "unique3"))

Deepak Over a year ago

Try const myConst: any = getCodes(); or const myConst: any[] = getCodes();

|

Serge · Accepted Answer · 2021-12-20 18:30:29Z

1

you can try this code

  var item= findItem(myConstant.data, "key3","unique3");

function

function findItem(items, key,value) {
      const result = items.filter(function(item) {
       for (const property in item)
         if(property==key && item[property]==value) return item;
        });
       return result != undefined ? result[0] : null;
    };

result

{
  "key1": "5",
  "key2": "extract",
  "key3": "unique3"
}

edited Dec 20, 2021 at 18:30

answered Dec 20, 2021 at 18:11

Serge

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