| #Name: Multiple Field Key to Single Field Key for Relates using Python and ArcPy | |
| #Author: Bryan McIntosh | |
| #Description: For updating a single LINK_ID field in both the parent and child table | |
| # based on a natural 4 column composite index relationship. | |
| import arcpy | |
| ## VARIABLES ## | |
| edit_ws = r'C:\SpatialTimes.gdb' #Edit workspace | |
| xs_fc = r'C:\SpatialTimes.gdb\CrossSection' #parent FC | |
| xs_tbl = r'C:\SpatialTimes.gdb\CrossSection_RatingCurves' #related table | |
| xs_att = ['Link_ID','F1','F2','F3','F4','OID@'] | |
| ## FUNCTIONS ## | |
| def fnUpdateXSTBL(qry, linkID): | |
| with arcpy.da.UpdateCursor(xs_tbl,xs_att, qry) as cursor2: | |
| for row in cursor2: | |
| row[0] = linkID | |
| cursor2.updateRow(row) | |
| ## MAIN CODE ## | |
| edit = arcpy.da.Editor(edit_ws) #Set the edit workspace | |
| edit.startEditing(False, False) #Note: change second param to true if using SDE WS | |
| with arcpy.da.UpdateCursor(xs_fc, xs_att) as cursor: | |
| for row in cursor: | |
| row[0] = row[5] #Makes the LinkID equal to the current ObjectID of parent | |
| cursor.updateRow(row) #Update the parent row | |
| #Set the query for the multi-field natural key (fields are F1, F2, F3, F4) | |
| xs_tbl_qry = xs_att[1] + " = '{0}' AND ".format(row[1]) + xs_att[2] + " = '{0}' AND ".format(row[2]) + xs_att[3] + " = '{0}' AND ".format(row[3]) + xs_att[4] + " = {0}".format(row[4]) | |
| fnUpdateXSTBL(xs_tbl_qry, row[5]) # Send the query and parent ObjectID to update the related table | |
| edit.stopEditing(True) |