# \[Resolved\] Duplicate error messages in Aurelia Validation

**URL:** <https://discourse.aurelia.io/t/resolved-duplicate-error-messages-in-aurelia-validation/2954>\
**Category:** Help Requests\
**Created:** [September 26, 2019, 2:45pm UTC](https://discourse.aurelia.io/t/resolved-duplicate-error-messages-in-aurelia-validation/2954 "2019-09-26T14:45:44Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![roddharris](https://yyz1.discourse-cdn.com/flex027/user_avatar/discourse.aurelia.io/roddharris/32/1340_2.png) [@roddharris](https://discourse.aurelia.io/u/roddharris)\
**Post date:** [September 26, 2019, 2:45pm UTC](https://discourse.aurelia.io/t/resolved-duplicate-error-messages-in-aurelia-validation/2954/1 "2019-09-26T14:45:44Z")

</div>

**Resolution** Thanks to [this post on StackOverflow](https://stackoverflow.com/questions/45525964/aurelia-dialog-repeated-validation), I realized I needed to create a `NewInstance` of my `ValidationController`.

```
//constructor of map.ts -- Map View Model
import {NewInstance} from 'aurelia-framework';

static inject = [NewInstance.of(ValidationController)]
constructor(public vc : ValidationController){ ... }

```

**Original Post**  
I’m composing a view-model that uses `aurelia-validation` to validate a specific class in my view-model. The properties of the class are bound to the `input` fields of the view and use the `& validate` extension.

I’m not using `aurelia-navigation` to switch between view-models in this case. What I’m finding is that each time I switch away from the view and back to it, I start getting an additional (duplicate) error message for each property. IOW, on my first visit the the view, if I leave the Name field blank, I get the appropriate error message: “Name is required”. However, if I switch to a different view, switch back to the original view and then leave the Name field blank, I now get TWO error messages stating that “Name is required”.

I then noticed that in re-setting the form, I instantiate a new instance of the property on my vm and I also start getting duplicate messages. So, it appears that because of where I’m defining my `ValidationRules` (in the same file as my class – see csv-importer.ts below), the rules keep being added every time I instantiate an instance of the class.

**Where/when should i be declaring my ValidationRules to keep them from being duplicated?** I was trying to only create `ValidationRules` when I need them – IOW, when the user gets to a view that will be working with validation. I could probably define my rules in `app.ts`, but that seems like overkill to have to define all the validation rules for my app in `app.ts` – even for many objects that may not ever be edited by the user. Is there a better way to handle this?

**UPDATE:** I was able to fix the issue by removing the initialization of the property in the declaration:  
**UPDATE 2:** Apparently I did not fix the issue when switching between views – only the issue with resetting the page.

`public importer : CsvImporter; //in map.ts`

and calling `this.resetPage()` in `activate()`. However, I’m still curious why the initializing was causing a problem. It appears that I re-initialize the object `this.importer = new CsvImporter();` without causing problems – just not if I do it in the declaration. VERY confused as to what is happening.

Here are code snippets to help show what I’m doing.

**map.ts**

```
import {CsvImporter} from 'models/csv-importer';
import {ValidationController} from 'aurelia-validation';
import {MyValidationRenderer} from 'resources/validation/my-validation-renderer';
export class Map {
    public importer : CsvImporter = new CsvImporter();

    static inject = [ValidationController]
    constructor(public vc = ValidationController){
        this.vc.addRenderer(new MyValidationRenderer());
    }

   resetPage(){
       this.importer = new CsvImporter();
    }
}

```

**map.html**

```
<input type="text" value.bind="importer.name & validate" />
<input type="text" value.bind="importer.description & validate" />
...
<button click.delegate="resetPage()">Reset</button>

```

**csv-importer.ts**

```
import {ValidationRules} from 'aurelia-validation';
export class CsvImporter {
   public name : string = "";
   public description : string = "";
    ...
}

ValidationRules
    .ensure((m: CsvImporter) => m.name).required()
    .ensure((m: CsvImporter) => m.description).required()
    .on(CsvImporter);
```