Array of objects on a json - http put

Question

I have the following Json structure on my project:

"disputas": [
    {
      id: "",
      tipo_negociacao: "",
      historico:[{
         fl_usuario: "",
         created_at: "",
         updated_at: "",
         created_by: null,
         updated_by: null,
         texto: "",
      }]
    }
]

I want to add a new index of historico when I click on a button but don't know how to do it, I want it to look like this:

 "disputas": [
        {
          id: "",
          tipo_negociacao: "",
          historico:[{
             fl_usuario: "",
             created_at: "",
             updated_at: "",
             created_by: null,
             updated_by: null,
             texto: "",
          },
           {
             fl_usuario: "",
             created_at: "",
             updated_at: "",
             created_by: null,
             updated_by: null,
             texto: "",
          }

       ]
    }
]

So far, I've done something like this (function that the button calls):

     recusaProposta() {
        this.disputa.historico[this.i].texto = "something";   
        this.i++;
}

now, since i starts on 0 this works on the first time I click on the button, but if I click on it again I'll get this error:

Cannot set property 'texto' of undefined

Can someone help me? thanks

Sushanth -- · Answer 1 · 2017-04-07T17:56:08.107

1

You run into the error

Cannot set property 'texto' of undefined

when you try to access a property on a undefined or null object.

You will first have to create a empty object in its place, if not already existing. The way your code is, it is expecting the object to be present in the index you are trying to access.

var existingObj = this.disputa.historico[this.i];

// if the value is falsy, then go ahead and create
// an empty object at that index
if(!existingObj) {
   this.disputa.historico[this.i] = {};
}

existingObj.texto = "something";

edited Apr 07 '17 at 17:56

answered Apr 07 '17 at 17:50

Sushanth --

55,259
9
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Thanks for the answer, there are more simple solutions as I discovered now on the other answers, but this one makes sense and has a very nice explanation. Thank you – Renê Silva Lima Apr 07 '17 at 18:01
@RenêSilvaLima You are welcome :) – Sushanth -- Apr 07 '17 at 18:03

score 1 · Answer 2 · answered Apr 07 '17 at 17:52

1

Just append an array:

this.disputa.historico.push({/* your object here*/});

answered Apr 07 '17 at 17:52

ghostprgmr

488
2
11

score 1 · Accepted Answer · answered Apr 07 '17 at 17:53

1

Just push a new item to the historico array:

this.disputa.historico.push({
fl_usuario: "",
             created_at: "",
             updated_at: "",
             created_by: null,
             updated_by: null,
             texto: ""
});

answered Apr 07 '17 at 17:53

Daniel AG

320
1
9

score 0 · Answer 4 · edited Apr 08 '17 at 07:26

0

Try this

disputas.historico.push({/* obj*/});

edited Apr 08 '17 at 07:26

goto

7,908
10
48
58

answered Apr 07 '17 at 17:55

Prakash Sundar

40
2

1

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - [From Review](/review/low-quality-posts/15777175) – Ricardo Alvaro Lohmann Apr 07 '17 at 19:11
@RicardoAlvaroLohmann Link? What link? – Pang Apr 08 '17 at 04:07

Array of objects on a json - http put

4 Answers4