Honour Validation attributes

[benfoster]

Currently only type checking is performed. It would be good if the object adaptor also honoured validation attributes on the object for example:

        [Range(18, 65)]
        public int Age { get; set; }

Currently I could set the age property to 10 using a patch operation.

[dougbu]

Object validation of HTTP data using validation attributes is an MVC feature. What is your end-to-end scenario? Why have you chosen not to use MVC in this scenario?

[benfoster]

We are using MVC. In the above scenario we'd have to manually invoke the validator on every patched object. You're currently doing type checking - it would be good if we had the ability to override this behaviour to also perform additional validation.

[Eilon]

Seems reasonable to me, but this isn't planned at this time.

[aelghoneimy]

Maybe you could do a separate Package to augment JsonPatch for MVC purposes, like Microsoft.AspNetCore.JsonPatch.MVC, which will have Validation Attributes and Bind Attribute checking.

[arielcloud]

+1 for this feature

[arielcloud]

Also, It'll be great to honour validation rules of fluentValidation

[RehanSaeed]

For those looking for a copy paste solution to this, you need to call TryValidateModel which adds any model errors to the ModelState for you and then you can check the model:

// Check that JSON patch document is valid.
if (!this.ModelState.IsValid)
{
    return this.BadRequest(this.ModelState);
}

patch.SafeApplyTo(model, this.ModelState);
this.TryValidateModel(model);
// Check that modified model is valid.
if (!this.ModelState.IsValid)
{
    return this.BadRequest(this.ModelState);
}

It's also worth noting that the JSON patch document could also be invalid, so you need to check the model state twice.

If you are using ASP.NET Core 1.0, then note that ApplyTo throws exceptions if the JSON patch document is invalid (More info and a workaround here). This was fixed in ASP.NET Core 1.1, where it adds model state errors instead.

[Eilon]

Closing because there are no plans to implement this.

Using TryValidateModel is the best way to do this.

[RehanSaeed]

@Eilon Is this because of the disconnect between ASP.NET Core and MVC? I've heard there are plans to remove that disconnect although that statement is vague, could this issue be reopened once that happens?