topic Re: da.UpdateCurso: Where clause for geometry in Python Questions

da.UpdateCurso: Where clause for geometry

Marianne_BilstedWiese — Thu, 06 Feb 2014 08:46:27 GMT

Hi Forum

I have a versioned database, where I want to make short lines longer. So in Python I try to select the short lines like this

 >>> uCursor = arcpy.da.UpdateCursor(inFeatures, [ 'OID@', 'SHAPE@', 'GM_LABEL', 'GM_USER_DEF' ], 'SHAPE@LENGTH < 300' ) edit = arcpy.da.Editor(arcpy.env.workspace) edit.startEditing() edit.startOperation()

which goes without problems but on

line = uCursor.next()

I get this error

Runtime error  Traceback (most recent call last):   File "<string>", line 1, in <module> RuntimeError: Underlying DBMS error [ORA-04054: databaselink LENGTH does not exist ] [G100.geopoint_line]

I tried also this where clause, that works in ArcMap Select by attributes:

SHAPE.LEN < 300

Because there is also a field called SHAPE.LEN.
I tried with and without quotes with no success.

Is it possible at all to make a constraint based on geometry?

/Marianne

Re: da.UpdateCurso: Where clause for geometry

JakeSkinner — Thu, 06 Feb 2014 11:10:44 GMT

Hi Marianne,

You will want to use the field name in the where clause. Ex:

uCursor = arcpy.da.UpdateCursor(inFeatures, [ 'OID@', 'SHAPE@', 'GM_LABEL', 'GM_USER_DEF' ], 'SHAPE.LEN < 300' )

Re: da.UpdateCurso: Where clause for geometry

XanderBakker — Fri, 10 Dec 2021 23:05:06 GMT

Hi Marianne,

What you could also try is to use the properties of the data you're accessing. So read the "lengthFieldName" properties after doing a describe on your data:

desc = arcpy.Describe(inFeatures)
fldLength = desc.lengthFieldName

Next, construct the expression. Make use of "AddFieldDelimiters" which will add the appropriate field delimiter if necessary:

minLength = 300
expression = "{0} < {1}".format(arcpy.AddFieldDelimiters(inFeatures, fldLength), minLength)

In my (non-versioned) SDE the expression will be:
"Shape.len" < 300

In a FGDB it will be:
Shape_Length < 300

Then continue with the UpdateCursor:

fields =  ['OID@', 'SHAPE@', 'GM_LABEL', 'GM_USER_DEF']
uCursor = arcpy.da.UpdateCursor(inFeatures, fields, expression)

Kind regards,

Xander

Re: da.UpdateCurso: Where clause for geometry

Marianne_BilstedWiese — Thu, 06 Feb 2014 15:24:27 GMT

Hi Marianne,

You will want to use the field name in the where clause. Ex:
uCursor = arcpy.da.UpdateCursor(inFeatures, [ 'OID@', 'SHAPE@', 'GM_LABEL', 'GM_USER_DEF' ], 'SHAPE.LEN < 300' )

Oh, simple as that!
Works like a charm, thanks.

-- But where is the 'accepted answer' button?

And also thanks, xander, this might be useful another time

/Marianne