Can JSON Schema support constraints on array items at specific indexes

jsonschema

Solution

Yes it can be done, here is an example of an array with the three first item type specified:

{
    "type": "array",
    "items": [
      {
        "type": "number"
      },
      {
        "type": "string"
      },
      {
        "type": "integer"
      }
    ]
}

When you validate the schema the 1st, 2nd and 3rd item need to match their type.

If you have more than four items in your array, the extra ones dont have a specified type so they wont fail validation also an array with less than 3 items will validate as long as the type for each item is correct.

Source and a good read I found last week when I started json schema: Understanding JSON Schema (array section in page 24 of PDF)

ps: english it's not my first languaje, let me know of any mistake in spelling, punctuation or grammar

Problem

A good schema language will allow a high degree of control on value constraints. My quick impression of JSON Schema, however, is that one cannot go beyond specifying that an item must be an array with a single allowable type; one cannot apparently specify, for example, that the first item must be of one type, and the item at the second index of another type. Is this view mistaken?

Original source