fastify: endpoint with query param as array limitation

[Xavier-Redondo]

Context

We define an endpoint that has a query param that is an array.

This is exemplified in this PR: #133

For this issues we are referring to the following endpoint defined in the api:

 "/array-query-param" :{
      "get": {
        "operationId": "queryParamAsArray",
        "summary": "Generates an array with all the input query params",
        "parameters": [
          {
            "name": "chickenIds",
            "in": "query",
            "required": true,
            "schema": {
              "type": "array",
              "items": {
                "type": "string"
              },
              "minItems": 1,
              "maxItems": 1000
            },
            "style": "form",
            "explode": true
          }
        ],
        "responses": {
             // Removed to reduce size
        }
      }
    },

According to this endpoint, these url's should be valid:

http://localhost:8080/api/array-query-param?chickenIds=2&chickenIds=3
http://localhost:8080/api/array-query-param?chickenIds=2

The first url, which has two elements, is correctly validated and we get a response.

Current behaviour

The second url, which has only one element, is not correctly validated and instead of having an array with one element we get the following validation error:

{"statusCode":400,"error":"Bad Request","message":"The request was not valid"}

with the following error log in the server:

js {"level":30,"time":1705507465376,"pid":50352,"hostname":"xxx","reqId":"req-1","res":{"statusCode":400},"err":{"type":"ValidationError","message":"The request was not valid","stack":"Validation Error: The request was not valid \n {\n \"name\": \"Validation Error\",\n \"errors\": [\n {\n \"path\": \"#/properties/chickenIds/type\",\n \"location\": \"querystring\",\n \"message\": \"must be array\",\n \"errorCode\": \"type\"\n }\n ],\n \"statusCode\": 400,\n \"message\": \"The request was not valid\"\n}","aggregateErrors":[{"type":"Object","message":"must be array","stack":"","path":"#/properties/chickenIds/type","location":"querystring","errorCode":"type"}],"name":"Validation Error","errors":[{"path":"#/properties/chickenIds/type","location":"querystring","message":"must be array","errorCode":"type"}],"statusCode":400},"msg":"The request was not valid"}

Expected behaviour

Even with one element we should treat this as an array of one element and not throw a validation error.

[franher]

@Xavier-Redondo thank you for the issue. Is this duplicated with #135 ?