Return array for single json object from webservice

Question

I'm retreiving json from a webservice and iterating through the hierarchy using $.each(). The problem I have is with the "Titles", there may be a single title or multiple. How do I force the "Titles" to return an array of objects, even if there is only a single object in the collection so $.each() doesn't blow up.

'VB Webservice...
ds.DataSetName = "dsSurveys"
ds.Tables(0).TableName = "Surveys"
ds.Tables(1).TableName = "Titles"
ds.Tables(2).TableName = "Questions"
ds.Tables(3).TableName = "ResponseTypes"

Dim relSurveyTitles As New DataRelation("relSurveyTitles", ds.Tables("Surveys").Columns("SurveyId"), ds.Tables("Titles").Columns("SurveyId"))
Dim relTitlesQuestions As New DataRelation("relTitlesQuestions", ds.Tables("Titles").Columns("TitleId"), ds.Tables("Questions").Columns("TitleId"))
Dim relResponseTypesQuestions As New DataRelation("relResponseTypesQuestions", ds.Tables("ResponseTypes").Columns("ResponseTypeId"), ds.Tables("Questions").Columns("ResponseTypeId"))

relSurveyTitles.Nested = True
relTitlesQuestions.Nested = True
relResponseTypesQuestions.Nested = False

ds.Relations.Add(relSurveyTitles)
ds.Relations.Add(relTitlesQuestions)
ds.Relations.Add(relResponseTypesQuestions)

Dim doc As New XmlDocument()
doc.LoadXml(ds.GetXml())
Dim jsonText As String = JsonConvert.SerializeXmlNode(doc).Replace("null", """""").Replace("'", "'")
Return jsonText

//json response
{
    "dsSurveys": {
        "Surveys": {
            "SurveyId": "1",
            "SurveyName": "Survey 1",
            "Titles": {     //I would like to see this in an array (like "Questions") --> "Titles": [{
                             //regarless of object count
                "SurveyId": "1",
                "TitleId": "1",
                "TitleName": "Title 1",
                "Questions": [{
                    "SurveyId": "1",
                    "TitleId": "1",
                    "QuestionId": "1",
                    "Question": "Question 1?",
                    "isComment": "true",
                    "ResponseTypeId": "1"
                },
                {
                    "SurveyId": "1",
                    "TitleId": "1",
                    "QuestionId": "2",
                    "Question": "Question 2?",
                    "isComment": "true",
                    "ResponseTypeId": "1"
                }]
            }
        },
        "ResponseTypes": {
            "ResponseTypeId": "1",
            "ResponseType": "Yes|No|N/A"
        }
    }
}

Run Object.keys on titles. This returns an array of property keys present on the title object. You can access the object properties by using titles[key]. — Mouser
– Mouser, Commented Jan 8, 2015 at 17:01

Mark · Accepted Answer · 2015-01-08 18:10:05Z

Looking at the documentation, it appears that you can force Titles to serialize as an array, even if there is only one occurrence, by adding a json:Array='true' attribute (where the json namespace is http://james.newtonking.com/projects/json) to the <Titles> nodes.

You could add the appropriate attributes using something like this:

Dim doc As New XmlDocument()
doc.LoadXml(ds.GetXml())

' Add the namespace declaration to the root node
Dim nsAttr = doc.CreateAttribute("xmlns", "json", "http://www.w3.org/2000/xmlns/")
nsAttr.Value = "http://james.newtonking.com/projects/json"
doc.DocumentElement.Attributes.Append(nsAttr)

' Add the json:Array attribute to each Titles element
For Each title As XmlElement In doc.SelectNodes("//Titles")
    Dim attr = doc.CreateAttribute("json:Array", "http://james.newtonking.com/projects/json")
    attr.Value = "true"
    title.Attributes.Append(attr)
Next

Dim jsonText As String = JsonConvert.SerializeXmlNode(doc).Replace("null", """""").Replace("'", "'")
Return jsonText

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