topic Find Specific Field Name in MXD Layers in Python Questions

Find Specific Field Name in MXD Layers

MitchHolley1 — Fri, 10 Dec 2021 23:07:30 GMT

I am trying to find a specific field name in layers in a current working MXD, but I'm having problems getting it right. The overall goal is to loop through layers in an MXD and set a definition query based on a user input (string type). The script runs without any errors, but no definition query is set.

Could it be because the type returned by the arcpy.Describe().fields function is Unicode?

Any help or advice is greatly appreciated!

import arcpy

#User input as 'String' type
feederID = arcpy.GetParameterAsText(0)

#Variables
mxd = arcpy.mapping.MapDocument("CURRENT")
df = arcpy.mapping.ListDataFrames(mxd)[0]


#Set definition query to user set parameters
for lyr in arcpy.mapping.ListLayers(mxd, "", df):
    fields = arcpy.Describe(lyr).fields
    for f in fields:
        if f.Name == "FEEDERID":
            lyr.definitionQuery = """FEEDERID = """ + "'" + str(feederID) + "'"
        
            
arcpy.RefreshActiveView()
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Re: Find Specific Field Name in MXD Layers

forestknutsen1 — Thu, 29 Sep 2016 18:56:01 GMT

What about saving the mxd with arcpy? One would think that the call to arcpy.RefreshActiveView() would do it, but...

You could also add the below just to make it a little safer...

if lyr.supports("DEFINITIONQUERY"):

Re: Find Specific Field Name in MXD Layers

MitchHolley1 — Thu, 29 Sep 2016 19:09:17 GMT

This addition was added to the script but still no results.

Re: Find Specific Field Name in MXD Layers

JoshuaBixby — Thu, 29 Sep 2016 20:39:43 GMT

Is feederID a number? If so, does this work?

lyr.definitionQuery = "FEEDERID = " + str(feederID)‍

Re: Find Specific Field Name in MXD Layers

DanPatterson_Retired — Thu, 29 Sep 2016 20:40:20 GMT

did you throw in some prints to see what is returned .....and no... unicode is just fine.. it is the way of the future that began many years ago when 3.x was introduced

Re: Find Specific Field Name in MXD Layers

DarrenWiens2 — Fri, 10 Dec 2021 23:07:32 GMT

This works for me:

>>> mxd = arcpy.mapping.MapDocument("CURRENT")
... df = arcpy.mapping.ListDataFrames(mxd)[0]
... feeder_field = "FEEDERID"
... value = "something"
... for lyr in arcpy.mapping.ListLayers(mxd, "", df):
...     fields = arcpy.Describe(lyr).fields
...     for f in fields:
...         if f.Name == feeder_field:
...             delim = arcpy.AddFieldDelimiters(lyr,feeder_field)
...             lyr.definitionQuery = delim + "='" + value + "'"‍‍‍‍‍‍‍‍‍‍

Re: Find Specific Field Name in MXD Layers

MitchHolley1 — Fri, 30 Sep 2016 14:02:24 GMT

Darren,

Thanks for the help.

I am currently running this Pythron script (v. 2.7.8) as a Script tool in a toolbox in ArcMap (v. 10.3.1).

When I test the code in the Python Window in ArcMap, I am able to list the fields in the (for f in fields:) loop. But, at the end of the prints, I am getting this error.

Any ideas as to why?

Re: Find Specific Field Name in MXD Layers

JoshuaBixby — Fri, 30 Sep 2016 15:42:40 GMT

Are you looping over fields in a layer or multiple layers? If the latter, are any of them group layers, map service layers, etc.... The error you describe will get generated if you try to return the fields of a layer that doesn't have fields.

Re: Find Specific Field Name in MXD Layers

MicahBabinski — Fri, 10 Dec 2021 23:07:35 GMT

I'd try:

#Set definition query to user set parameters
for lyr in arcpy.mapping.ListLayers(mxd, "", df):
    if lyr.isFeatureLayer: #<---this bit will ensure you are trying to access the fields of only feature layers
        fields = arcpy.Describe(lyr).fields
        for f in fields:
            if f.Name == "FEEDERID":
                lyr.definitionQuery = """FEEDERID = """ + "'" + str(feederID) + "'"

Re: Find Specific Field Name in MXD Layers

MitchHolley1 — Mon, 03 Oct 2016 16:20:57 GMT

Micah,

Thank you very much for the response, but now I'm getting a different error.

Could this be because the layers I'm trying to set a definition query for are in a feature dataset?

Re: Find Specific Field Name in MXD Layers

MitchHolley1 — Mon, 03 Oct 2016 16:25:59 GMT

Josh,

Thank you for the time and the response. The layers are multiple map layers in a feature dataset residing in an enterprise geodatabase.

Re: Find Specific Field Name in MXD Layers

MicahBabinski — Mon, 03 Oct 2016 16:34:51 GMT

Hmmm. Can you post the script that yielded this error? It looks like the error was caused by the lyr variable not being a valid input to the describe function.

Re: Find Specific Field Name in MXD Layers

MitchHolley1 — Mon, 03 Oct 2016 16:38:36 GMT

I actually figured out the issue. I believe it was because I had layers in the MXD with broken data sources.

Thank you!!

Re: Find Specific Field Name in MXD Layers

MitchHolley1 — Fri, 10 Dec 2021 23:07:38 GMT

All,

I finally got the script to successfully run thanks to all the kind people in this community. Below is the final code.

Dan Patterson‌ is there a way to mark several people's replies as the correct answer? This seems like it was a team effort since everyone contributed to the overall answer.

import arcpy

#Get input from user
feederID = arcpy.GetParameterAsText(0)
ischecked = arcpy.GetParameterAsText(1)

#Variables
mxd = arcpy.mapping.MapDocument("CURRENT")
field = "FEEDERID"

for lyr in arcpy.mapping.ListLayers(mxd):
    if lyr.isFeatureLayer:
        fields = arcpy.Describe(lyr).fields
        for f in fields:
            if f.Name == field:
                delim = arcpy.AddFieldDelimiters(lyr,field)
                lyr.definitionQuery = delim + "='" + feederID + "'"
            
#Clear definition query           
if ischecked == 'true':
    for lyr in arcpy.mapping.ListLayers(mxd):
        if lyr.isFeatureLayer:
            lyr.definitionQuery = ""
            
arcpy.RefreshActiveView()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Find Specific Field Name in MXD Layers

DanPatterson_Retired — Mon, 03 Oct 2016 17:29:37 GMT

No multiple correct... so your options are to

'Helpful' all those that contributed
pick one as the most helpful either singularly, or cumulatively
mark it as 'assumed answered' if you can't pick one