Q:

Array of objects on a json - http put

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

A:

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: ""
});

