问题
Problem
Description
I'm currently running into a problem where the JSON that I am getting back has fields that are null.
In the code below, I've figured out that most of the fields have an assignee, and down another level assignees have a displayName. I've also found out that some things do not have an assignee. When that happens (and this would probably happen with other fields too, I'm just using this as an example) it removes that additional heirarchy level, and the actual path (also shown below) would be changed.
Question
Is there an easy way to iterate over this response, and set nulls to blanks maybe?
Set Json = JsonConverter.ParseJson(MyRequest.ResponseText)
That doesn't really help me with automation though. Notice [below] where I list components twice, because I don't know how to loop through that data and pull back the field as many times as it needs to be populated. Aka I know there are two components, but it only brings back one component, so I had to copy that code to get it to work correctly (I'm sorry for copying).
Code Snip
My code works great until it hits a null, then it throws an error.
''''''''
' Loop '
''''''''
For i = 0 To 40
' ActiveSheet.Cells(i + 1, 1) = Json("issues")(i + 1)("fields")("issuetype")("name")
' ActiveSheet.Cells(i + 1, 2) = Json("issues")(i)("key")
' ActiveSheet.Cells(i + 1, 3) = Json("issues")(i + 1)("fields")("summary")
' ActiveSheet.Cells(i + 1, 4) = Json("issues")(i + 1)("fields")("status")("name")
ActiveSheet.Cells(i + 1, 5) = Json("issues")(i + 1)("fields")("assignee")
ActiveSheet.Cells(i + 1, 5) = Json("issues")(i + 1)("fields")("assignee")("displayName")
' ActiveSheet.Cells(i + 1, 6) = Json("issues")(i + 1)("fields")("customfield_13301")
' ActiveSheet.Cells(i + 1, 7) = Json("issues")(i + 1)("fields")("components")(1)("name")
' ActiveSheet.Cells(i + 1, 8) = Json("issues")(i + 1)("fields")("components")(2)("name")
' ActiveSheet.Cells(i + 1, 9) = Json("issues")(i + 1)("fields")("customfield_13300")
' ActiveSheet.Cells(i + 1, 10) = Json("issues")(i + 1)("fields")("customfield_10002")
Next i
JSON
Ovbiously I had to delete some content for privacy reasons, but that shows the assignee as null. JSON with a, "displayName" just turns that null into an Array and has more fields under it.
{
"expand": "schema,names",
"startAt": 0,
"maxResults": 50,
"total": 52,
"issues": [
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{
"expand": "operations,versionedRepresentations,editmeta,changelog,renderedFields",
"id": "92110",
"self": "",
"key": "",
"fields": {
"customfield_13100": null,
"fixVersions": [],
"customfield_13500": null,
"customfield_11200": null,
"resolution": null,
"customfield_13502": null,
"customfield_13501": null,
"lastViewed": null,
"customfield_12000": null,
"customfield_12002": null,
"customfield_12001": null,
"priority": {},
"customfield_10100": null,
"customfield_10101": null,
"customfield_12003": null,
"customfield_12402": null,
"labels": [],
"customfield_11303": null,
"customfield_11305": null,
"customfield_11306": null,
"aggregatetimeoriginalestimate": null,
"timeestimate": null,
"versions": [],
"issuelinks": [],
"assignee": null,
"status": {},
"components": [],
"customfield_13200": null,
"customfield_13600": null,
"customfield_12900": null,
"aggregatetimeestimate": null,
"creator": {},
"customfield_14000": null,
"subtasks": [],
"customfield_14400": null,
"reporter": {},
"customfield_12101": null,
"customfield_12100": null,
"aggregateprogress": {},
"customfield_14401": null,
"customfield_14402": null,
"customfield_12500": null,
"customfield_13702": null,
"customfield_13704": null,
"customfield_13703": null,
"customfield_11802": null,
"progress": {},
"votes": {},
"issuetype": {},
"timespent": null,
"project": {},
"customfield_13300": null,
"aggregatetimespent": null,
"customfield_13302": null,
"customfield_13301": null,
"customfield_13700": null,
"customfield_11400": null,
"resolutiondate": null,
"workratio": -1,
"watches": {},
"created": "2017-07-21T08:04:42.000-0500",
"customfield_14102": null,
"customfield_10020": null,
"customfield_12200": null,
"customfield_14100": null,
"customfield_14101": null,
"customfield_12600": null,
"customfield_14500": null,
"customfield_10300": null,
"customfield_10016": null,
"customfield_13405": null,
"customfield_10017": null,
"customfield_13800": null,
"customfield_10018": null,
"customfield_10019": null,
"customfield_13409": null,
"updated": "2017-08-10T15:29:37.000-0500",
"timeoriginalestimate": null,
"description": null,
"customfield_10011": null,
"customfield_10012": null,
"customfield_13401": null,
"customfield_13400": null,
"customfield_10013": null,
"customfield_10014": null,
"customfield_11500": "{}",
"customfield_10015": null,
"customfield_13514": null,
"summary": "",
"customfield_14200": null,
"customfield_10000": null,
"customfield_13511": null,
"customfield_12301": null,
"customfield_10001": null,
"customfield_12300": null,
"customfield_10002": "1|i021pe:5z",
"customfield_13510": null,
"customfield_13513": null,
"customfield_10003": [],
"customfield_12302": null,
"customfield_10004": null,
"customfield_13504": null,
"customfield_13503": null,
"customfield_11600": null,
"customfield_13506": null,
"environment": null,
"customfield_13901": null,
"customfield_13505": null,
"customfield_13508": null,
"duedate": null,
"customfield_13509": null
}
},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{},
{}
]
}
Additional Data
I looked at the Raw file just to see if anything looked different (than it did in my JSON Formater Plugin for Chrome) and this is what it looked like:
"assignee":null,
回答1:
Working with JSON files is much easier (IMHO) if you understand how the JsonConverter processes the JSON into a compound object. Let's look at a simple JSON format (taken from this useful site):
{
"array": [
1,
2,
3
],
"boolean": true,
"null": null,
"number": 123,
"object": {
"a": "b",
"c": "d",
"e": "f"
},
"string": "Hello World"
}
The JsonConverter maps each of these data items into their VBA counterparts.
"array" maps to Collection (anytime you see the square brackets []) "boolean" maps to Boolean "null" maps to Null "number" maps to Double "object" maps to Dictionary (anytime you see the curly braces {}) "string" maps to String
So now we can do useful things with your JSON example, such as determine how many entires are in your "issues" array by
Dim issues As Collection
Set issues = schema("issues")
Debug.Print issues.Count
Each of the entries in your "issues" array is actually a compound object itself, so it's a Dictionary. We could, therefore, do something like this:
Dim issue As Variant
For Each issue In issues
If issue.Exists("id") Then
Debug.Print "id = " & issue("id")
End If
Next issue
Of course, the "fields" section of this single issue is itself another Dictionary. So stacking up the dictionary references we can do this too:
Debug.Print "field summary is " & issue("fields")("summary")
All of this is background, hopefully to make it easier on accessing members of a JSON structure. Your real question is on handling NULLs. If the actual value of a field is set to null (see the above sample), then you check it like so
If IsNull(issue("fields")("customfield_13500")) Then ...
A couple of other side notes before we put it all together:
- Always use
Option Explicit - Avoid
SelectandActivate - Always define and set references to all Workbooks and Sheets
In the example below, you'll see that I assumed you had to check each field for Null. That is best accomplished by isolating that check in a subroutine rather than over-mess your code with a long string of If statements. The advantage of the code example below is that you don't have to hard-code the number of issues because your logic can detect how many there are.
Option Explicit
Sub main()
Dim schema As Object
Set schema = GetJSON("C:\dev\junk.json")
Dim thisWB As Workbook
Dim destSH As Worksheet
Set thisWB = ThisWorkbook
Set destSH = thisWB.Sheets("Sheet1")
Dim anchor As Range
Set anchor = destSH.Range("A1")
Dim issues As Collection
Set issues = schema("issues")
Dim i As Long
Dim issue As Variant
For Each issue In issues
If issue.Exists("id") Then
SetCell anchor.Cells(1, 1), issue("fields")("issuetype")("name")
SetCell anchor.Cells(1, 2), issue("key")
SetCell anchor.Cells(1, 3), issue("fields")("summary")
'--- if you're not sure if the "name" field is there,
' then remember it's a Dictionary so check with Exists
If issue("fields")("status").Exists("name") Then
SetCell anchor.Cells(1, 4), issue("fields")("status")("name")
Else
SetCell anchor.Cells(1, 4), vbNullString
End If
SetCell anchor.Cells(1, 5), issue("fields")("assignee")
SetCell anchor.Cells(1, 6), issue("fields")("customfield_13301")
'--- possibly get the Count and iterate over the exact number of components
For i = 0 To issue("fields")("components").Count - 1
SetCell anchor.Cells(1, 7), issue("fields")("components")(i)("name")
Next i
SetCell anchor.Cells(1, 9), issue("fields")("customfield_13300")
SetCell anchor.Cells(1, 10), issue("fields")("customfield_10002")
Set anchor = anchor.Offset(1, 0)
End If
Next issue
End Sub
Function GetJSON(ByVal filename As String) As Object
'--- first ingest the JSON file and get it parsed
Dim fso As FileSystemObject
Dim jsonTS As TextStream
Dim jsonText As String
Set fso = New FileSystemObject
Set jsonTS = fso.OpenTextFile(filename, ForReading)
jsonText = jsonTS.ReadAll
Set GetJSON = JsonConverter.ParseJson(jsonText)
End Function
Private Sub SetCell(ByRef thisCell As Range, ByVal thisValue As Variant)
If IsNull(thisValue) Then
thisCell = vbNullString
Else
thisCell = thisValue
End If
End Sub
回答2:
Fix
This is what I did to get this to work:
If IsNull(Json("issues")(i + 1)("fields")("components")) Then
ActiveSheet.Cells(i + 1, 5).Value = ""
Else
ActiveSheet.Cells(i + 1, 7) = Json("issues")(i + 1)("fields")("components")(1)("name")
End If
回答3:
You may get JSON data into arrays as shown in the example code below. Import JSON.bas module into the VBA project for JSON processing.
Sub Test()
' Put sourse JSON string to "\source.json" file, and save as ANSI or Unicode
Dim sJSONString As String
Dim vJSON As Variant
Dim sState As String
Dim aData()
Dim aHeader()
sJSONString = ReadTextFile(ThisWorkbook.Path & "\source.json", -2)
JSON.Parse sJSONString, vJSON, sState
vJSON = vJSON("issues")
JSON.ToArray vJSON, aData, aHeader
With Sheets(1)
.Cells.Delete
.Cells.WrapText = False
OutputArray .Cells(1, 1), aHeader
Output2DArray .Cells(2, 1), aData
.Columns.AutoFit
End With
End Sub
Sub OutputArray(oDstRng As Range, aCells As Variant)
With oDstRng
.Parent.Select
With .Resize(1, UBound(aCells) - LBound(aCells) + 1)
.NumberFormat = "@"
.Value = aCells
End With
End With
End Sub
Sub Output2DArray(oDstRng As Range, aCells As Variant)
With oDstRng
.Parent.Select
With .Resize( _
UBound(aCells, 1) - LBound(aCells, 1) + 1, _
UBound(aCells, 2) - LBound(aCells, 2) + 1)
.NumberFormat = "@"
.Value = aCells
End With
End With
End Sub
Function ReadTextFile(sPath As String, lFormat As Long) As String
' lFormat -2 - System default, -1 - Unicode, 0 - ASCII
With CreateObject("Scripting.FileSystemObject").OpenTextFile(sPath, 1, False, lFormat)
ReadTextFile = ""
If Not .AtEndOfStream Then ReadTextFile = .ReadAll
.Close
End With
End Function
来源：https://stackoverflow.com/questions/46225392/returning-null-json-throwing-type-mismatch-error-in-vba