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Nicolas Cavilla
Asked: 2020-09-13 08:30:32 +0800 CST 2020-09-13 08:30:32 +0800 CST

Update subdocument in mongodb

  • 772

I have the following schematics:

const AutorSchema = new Schema({

    nombre: {
        type: String,
        required: [true, "El nombre es requerido"]
    },
    apellido:{
        type: String,
        required: [true, "El apellido es requerido"]
    }

})

const LibroSchema = new Schema({

    titulo: {
        type: String,
        required: [true, "El titulo es requerido"]
    },

    editorial:{
        type: String,
        required: [true, "La editorial es requerida"]
    },

    autor:{
        type: AutorSchema,
        required: ["El autor es requerido"]
    }


})

When I want to update the author information and I only want to modify one of the Author attributes, only the field I wanted to update is saved and the others disappear. For example:

const autor = {
    data:{
        apellido: "Perez"
    }
}

Libro.findOneAndUpdate({_id: req.params.id}, autor);

/* 

Devuelve => 
    {
        titulo: "Libro1",
        editorial: "Editorial1",
        autor:{
            apellido: "Perez"
        }
    }

*/

As you can see the "name" attribute of the author disappears and only the new last name remains. How can I modify some of the attributes and keep the others?

javascript

1 Answers

  1. Best Answer

    As @JackNavaRow comments, you should use the operator $setto tell MongoDB that a field is being replaced and not the entire document.

    In addition, the field that you are going to update, since it is a field in an embedded document, you must indicate it using the dot notation.

    For example:

    let update = {
  $set: {
    'autor.nombre': 'Nicolas' // <- notación de punto sobre autor.nombre
  }
}

Libro.findOneAndUpdate({_id: req.params.id}, update, {new: true})
.then( ... )
.catch( ... );

    I hope this helps you solve the problem.

    EDITION

    In your comment you ask a very interesting question.

    If any of the jsonreceived fields is undefined, then we should not do the update, since it sets the a field nullin the document.

    The solution is to build the update object based on the information received.

    For example:

    let update = {};
let $set = {};
Object.keys(json_recibido).forEach(key => {
  if(json_recibido[key]) { // si el valor es distinto de undefined o null
    $set[key] = json_recibido[key];
  }
});

if(Object.keys($set).length) {
  update.$set = $set;
}
// ahora update sólo contiene los campos que no sean undefined o null

    Let's see an example of the above code working:

    const jsons = [
  {nombre: 'Mauricio', apellido: 'Contreras'},
  {nombre: 'Gonzalo JSBianchi', apellido: undefined},
  {nombre: 'Nicolas', apellido: undefined},
  {nombre: null, apellido: 'Cavilla'},
  {nombre: null, apellido: undefined}
  
];

jsons.forEach(json_recibido => {
  let update = {};
  let $set = {};
  Object.keys(json_recibido).forEach(key => {
    if(json_recibido[key]) { // si el valor es distinto de undefined o null
      $set[key] = json_recibido[key];
    }
  });

  if(Object.keys($set).length) {
    update.$set = $set;
  }
  console.log(update);
});
    .as-console-wrapper {
  min-height: 100%;
  top: 0;
}

    • 4