GoLang Validator Non-Required Fields Returns Error

Question

I'm using GoLang Validator on a struct to validate its fields. Even though I don't add required tag, it still behaves as if it is required.

type Order struct {
    // ... other fields
    UserID string `json:"userId" validate:"uuid4"`
    // ... other fields
}

if err = validator.New().Struct(i); err != nil {
    return err
}

Output: User ID: unknown error

It is not required hence the value is zero-value but it still returns an error. Am I doing something wrong here?

Eelco · Accepted Answer · 2022-06-21 13:01:02Z

6

You should add the omitempty validator to allow empty values. Try out the code below on Go playground.

    type Order struct {
        // ... other fields
        UserID string `json:"omitempty,userId" validate:"omitempty,uuid4"`
        // ... other fields
    }

    if err := validator.New().Struct(Order{}); err != nil {
        return err
    }

Note that to marshal the struct to JSON you also need to set the omitempty validator if you want to allow empty values...

answered Jun 21, 2022 at 13:01

Eelco

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2 Comments

TheRealChx101 Over a year ago

omitempty doesn't work. I still get an error Password field failed on the min tag. The field is optional but if specified, needs to have its length with a range (min=8,max=25)

Eelco Over a year ago

It does work fine when I try it: go.dev/play/p/aJ6b15hBqSr

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