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In the last lecture we detected this error when we change the value of our dropdown, it is related

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to our validation check in the contact data container. There in check validity,

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we check if rules required,

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the problem is rules,

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what does this get,

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what does rule of this argument refer to?

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Let's have a look at where we call check validity,

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we call it in the inputChangedHandler and we pass the update form element value

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and for rules, updatedFormElement validation.

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Now the thing is this validation object doesn't exist for the dropdown for delivery method,

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so if we then try to access required on something which doesn't exist, we get an error. Two ways of fixing

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that,

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the first way is simply add an empty validation object to the dropdown control.

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Now accessing validation required will not fail but simply return undefined,

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I like this way a lot because now all our controls are set up equally,

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they all have a validation property and a valid property,

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and if they don't need validation, then it should just be empty.

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This is why I like this approach.

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Now the alternative would have been to also add a check in check validity and see if rules,

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if this is true-ish which it only is if it is defined and if it is not true-ish, so by adding an exclamation

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mark, to simply return true then.

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So always return true for the check validity result if no validation rules are defined.

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We can of course also implement both for double security but again, I like the approach up here by adding

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this empty validation object the most because it makes all the controls configured equally.

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Now with this added, if I save this, now we can change the dropdown value again without getting errors

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as you can see.