Use function result value for UpdateRow()

[LanceWilson]

I have the following code below and my question is this:

How do I take the returning value of a function that I've defined and use it in an UpdateCursor (updateRow)? The issue is that I'm (obviously) getting an error with regards to the syntax type not being compatible.

Essentially, what I'm trying to do is take the "raw" number of total_seconds() and update a column in the rows to make them easier to read - i.e. instead of it saying 3454352 seconds, it will be in dd:hh:mm:ss. The function works fine, it is the "cursor.updateRow(row)" that draws the syntax error. I understand that it is because it will not accept a function as the input, so how do I take just the value of the function and use that as the criteria for cursor.updateRow(row) ? Thanks in advance for any help!

error:

\Toolbox_Python_SQL_Scripts\HISTORY_ARCHIVE_query.py", line 89, in <module>

    cursor.updateRow(row)

RuntimeError: The value type is incompatible with the field type. [Total_Time]

Failed to execute (HistoryArchiveScriptTool).

# import arcpy module
import arcpy

# Ask user to select the Geodatabase workspace to use for data output
userWorkspace = arcpy.GetParameterAsText(0)

# Set workspace environment based upon user's choice
arcpy.env.workspace = userWorkspace

# Ask user to select an Oracle dB Connection
oracleDB = arcpy.GetParameterAsText(1)

# Ask user to name the Query Layer
queryLayer = arcpy.GetParameterAsText(2)

# Ask user for an SQL Query Expression to be run against the selected Oracle dB
sqlQuery = arcpy.GetParameterAsText(3)

# Create spatial reference variable to assign to queryLayer
spatialRef = arcpy.SpatialReference("Vector\Coordinate Systems\WGS 1984.prj")

# Process: 'Make Query Layer' - Creates a Query Layer using the user's Oracle dB and SQL query expression
arcpy.MakeQueryLayer_management(oracleDB, "Temp_Layer", sqlQuery, "UNIQUE_ID", "POLYLINE", "1050010", spatialRef)

# Process: 'Copy Features' - Copies the temporary Query Layer and stores it as a permanent feature class
arcpy.CopyFeatures_management("Temp_Layer", queryLayer)

# Process: 'Define Projection' - Defines the projection of queryLayer feature class output
arcpy.DefineProjection_management(queryLayer, spatialRef)

# Process: 'Add Field' - Adds new column fields to queryLayer
arcpy.AddField_management(queryLayer, "First_Time", "DATE") # The first LOGDT ping
arcpy.AddField_management(queryLayer, "Last_Time", "DATE") # The last LOGDT ping
arcpy.AddField_management(queryLayer, "Total_Time", "FLOAT") # Summation of the first to last ping in time
arcpy.AddField_management(queryLayer, "Total_Pings", "INTEGER") # Total number of pings (rows)
arcpy.AddField_management(queryLayer, "Possible_Pings", "INTEGER") # Total number of pings possible in given timeframe
arcpy.AddField_management(queryLayer, "Time_to_Process", "DATE") # How long it took for each ping to process

# Calculates the total number of rows for newly added column Total_Pings
numRows = int(arcpy.GetCount_management(queryLayer).getOutput(0))

# UpdateCursor that will write the value of numRows to the Total_Pings column
cursor = arcpy.da.UpdateCursor(queryLayer, "Total_Pings")
for row in cursor:
    row[0] = numRows
    cursor.updateRow(row)

# SearchCursor that will read the values of LOGDT and return the first value (earliest)
firstLogdt = [row[0] for row in arcpy.da.SearchCursor(queryLayer, "LOGDT")][0]

# UpdateCursor that will write the first (earliest) LOGDT value to the field First_Time
cursor = arcpy.da.UpdateCursor(queryLayer, "First_Time")
for row in cursor:
    row[0] = firstLogdt
    cursor.updateRow(row)

# SearchCursor that will read the values of LOGDT and return the last value (latest)
lastLogdt = [row[0] for row in arcpy.da.SearchCursor(queryLayer, "LOGDT")][-1]

# UpdateCursor that will write the last (latest) LOGDT value to the field Last_Time
cursor = arcpy.da.UpdateCursor(queryLayer, "Last_Time")
for row in cursor:
    row[0] = lastLogdt
    cursor.updateRow(row)


# Calculates the difference between firstLogdt and lastLogdt
timeDiff = lastLogdt - firstLogdt # Produces a timedelta object, not datetime

# Calculates the total number of seconds from timeDiff
timeSecs = timeDiff.total_seconds()

# Creates a function that will convert timeDiff.total_seconds() to a readable format (dd:hh:mm:ss)
def readTime(seconds):
    minutes, seconds = divmod(seconds, 60)
    hours, minutes = divmod(minutes, 60)
    days, hours = divmod(hours, 24)
    return '%02d:%02d:%02d:%02d' % (days, hours, minutes, seconds)

# UpdateCursor that will write the time difference calculation to the new Total_Time field
cursor = arcpy.da.UpdateCursor(queryLayer, "Total_Time")
for row in cursor:
    row[0] = readTime(timeSecs)
    cursor.updateRow(row)

# Calculates the total number of pings that would occur if no pings were dropped
possiblePings = timeSecs / 5 # 1 ping every 5 seconds (with good reception)

# UpdateCursor that will write the total number of pings possible to the new Possible_Pings field
cursor = arcpy.da.UpdateCursor(queryLayer, "Possible_Pings")
for row in cursor:
    row[0] = possiblePings
    cursor.updateRow(row)

[DarrenWiens2]

What exactly does the syntax error say? AFAIK, by the time updateRow is called, it shouldn't care that the value was obtained from a function.

edit: I'll add that the following works perfectly fine, indicating that there is something else wrong with your script (possibly wrong data type?). Also, you should either use 'del cursor' or, better, "with arcpy.da.UpdateCursor" to ensure your cursor is deleted.

>>> myVal = 10
... def myFunc(val):
...     return val + 1
... cursor = arcpy.da.UpdateCursor("points","Id")
... for row in cursor:
...     row[0] = myFunc(myVal)
...     cursor.updateRow(row)

[LanceWilson]

Thanks for the suggestions, I have updated my question with the exact error and my full code.

[XanderBakker]

Darren Wiens provides some very good suggestions. First of all the exact error message is very helpful to determine what goes wring with your code.

Some additional suggestions:

• You call your function inside your update cursor, but the value will be the same for each record. Call it once outside the cursor (set a variable with the result) and use the variable for the output row value.
• What type of field are you writing the result to (I assume it is text, if not that will be a problem)?
• you are using a "querylayer" in the cursor. How is this querylayer set and where is it pointing. Do you have access to update this layer?

[LanceWilson]

Thanks for the suggestions, I have updated my question with the exact error and my full code.

Also, I am aware that the same value is going to be updated for all rows, this is fine and is what is supposed to happen for this particular set of data I have.

[DarrenWiens2 · Accepted solution]

Your field "Total_Time" is Float, but you are trying to force in the String returned from your function.

Change the data type to either String or Date, and make sure that's what your function returns.

[LanceWilson]

Darren,

Thanks for spotting that - I did as well too, but am unable to figure out exactly what I'm supposed to do to get the function value to work with the updateRow(row) ?

[XanderBakker]

I you want to write the string as a result, the field should be of type text. If you cannot change the field, then you should change the function to produce a float (numeric value with decimals). But looking at your code the idea is to generate a readable time text value.

[LanceWilson]

You are correct, for whatever reason I wasn't thinking and was doing something else. Thanks for the help!

[DarrenWiens2]

Make sure the new value you are trying to use is the same as, or compatible with, the field you are updating. ArcGIS doesn't know how to change "12:03:46:23" to a float value.