CODEWITHSUNDEEP
joi
fIwJlxSzApHEZIl
fIwJlxSzApHEZIl

Reputation: 13290

How do you validate an array in Joi with only one item?

I would like to accept an array of strings as an argument with Joi but when I pass only one item I receive the error value must be an array. If I try to pass a second value that's empty to force array syntax conversion in Express I receive must be one of... error after defining the strict set of possible values as empty is not strictly allowed.

Request schema:

const requestSchema = Joi.object().keys({
  query: Joi.object().keys({
    endTime: Joi.string().required(),
    fields: Joi.array().items(
      Joi.string().valid(
        "value1",
        "value2",
        "value3"
      )
    ),
    startTime: Joi.string().required()
  })
});

Upvotes: 2

Views: 4269

Answers (1)

fIwJlxSzApHEZIl
fIwJlxSzApHEZIl

Reputation: 13290

The key here is the single() function. Implementing this will allow you to pass a single value for an array and Joi will wrap the single value in an array so that it validates correctly:

const requestSchema = Joi.object().keys({
  query: Joi.object().keys({
    endTime: Joi.string().required(),
    fields: Joi.array().items(
      Joi.string().valid(
        "value1",
        "value2",
        "value3"
      )
    ).single(),
    startTime: Joi.string().required()
  })
});

This allows you to send fields=value1 which gets converted to: fields: ["value1"].

Upvotes: 2

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