Cannot coerce value into type: class java.util.date

Ignition
,
1

I'm very new to ignition and I'm trying to simulate the start and end of a process and logging the data in-between and exporting to a csv.
I have 2 buttons, one to start and one to stop. The start button assigns the current start time to a memory DateTime tag with the following script:

system.tag.writeBlocking(["[IsoTreat]StartTime"],[system.date.now()])

The second button then needs to use this value to find how far back to query to create the dataset, it uses the following code:


EndTime = system.date.now()

DataSet = system.tag.queryTagHistory(paths =[
        "[IsoTreat]Studio5000/AddititveScaled",
        "[IsoTreat]Studio5000/PowderScaled"], 
        startDate = ["[IsoTreat]StartTime"], 
        endDate = EndTime, 
        columnNames = 'Pot 1''Pot 2', 
        returnSize = 0
)

csv = system.dataset.toCSV(DataSet)

filePath = system.file.saveFile("myExport.csv", "csv", 
        "Comma Separated Values")

if filePath:
	system.file.writeFile(filePath, csv)

When I press the button I get the following error:

java.lang.ClassCastException: java.lang.ClassCastException: Cannot coerce value '['[IsoTreat]StartTime']' into type: class java.util.Date

caused by ClassCastException: Cannot coerce value '
    ['[IsoTreat]StartTime']' into type: class java.util.Date

any help would be greatly appreciated. Thanks.

2

Hi, Kieren and welcome.

Please have a quick read of Wiki - how to post code on this forum and then edit your post using the pencil icon. All your indentation is lost otherwise. Thanks.

3

Adding some air into your code makes it more readable and shows up a few issues.

EndTime = system.date.now()
DataSet = system.tag.queryTagHistory(paths = [
      "[IsoTreat]Studio5000/AddititveScaled", 
      "[IsoTreat]Studio5000/PowderScaled"
    ], 
    startDate = ["[IsoTreat]StartTime"],       <-- !
    endDate = EndTime, 
    columnNames = 'Pot 1''Pot 2',              <-- !
    returnSize = 0
)

In the line,
startDate = ["[IsoTreat]StartTime"]
you are supplying a string where a datetime is required. You need to retrieve that first as a separate operation.

tagStartDate = system.tag.readBlocking(["[IsoTreat]StartTime"])
DataSet = system.tag.queryTagHistory(paths = [
      "[IsoTreat]Studio5000/AddititveScaled", 
      "[IsoTreat]Studio5000/PowderScaled"
    ], 
    startDate = tagStartDate[0].value,
    endDate = EndTime,
    columnNames = ['Pot 1', 'Pot 2'],
    returnSize = 0
)

Note the fix on the columnNames list.

There may be more!

Edit: Fixed the line startDate = tagStartDate[0].value
The readBlocking function returns a list with a qualified value for each tag requested. The qualified value includes the actual value, the quality and the timestamp. Since we only read one tag it will be returned as tagStartDate[0] and the value can be read using tagStartDate[0].value. Thank you @Ujwal_Wankhede.

3 Likes
4

Thank you,

I've added in the changes you said, now I'm getting a similar error:

cannot coerce value '[[Mon Jun 03 10:27:56 AEST 2024, Good, Mon Jun 03 10:27:56 AEST 2024 (1717374476887)]]' into type: class java.util.Date

Is there maybe something wrong with the StartTime tag data type?

5

Please read this tread

You should make following modification to code work
startDate = tagStartDate[0].value

2 Likes
6

I made that change and it works now. Thanks to both of you