arcpy.management.AlterFields(in_table, {field_description})
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Имя
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Объяснение
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Тип данных
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in_table
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Входная таблица или класс объектов базы геоданных, которые содержат изменяемое поле.
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Table View; Raster Layer; Mosaic Layer
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field_description
[[Field Name, {New Field Name}, {New Field Alias}, {New Field Type}, {New Field Length}, {New Field IsNullable}, {Clear Alias}],...]
(Дополнительный)
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Поля входной таблицы и их свойства, которые будут изменены.
Столбцы таблицы значений:
Field Name–The name of the field that will be altered. If the field is a required field, only the field alias will be altered.
New Field Name–The new name for the field.
New Field Alias–The new field alias for the field.
New Field Type–Specifies the new field type for the field. This option is only applicable if the input table is empty (does not contain records).
SHORT–The field type will be short. Short fields support whole numbers between -32,768 and 32,767.
LONG–The field type will be long. Long fields support whole numbers between -2,147,483,648 and 2,147,483,647.
BIGINTEGER–The field type will be big integer. Big integer fields support whole numbers between -(253) and 253.
FLOAT–The field type will be float. Float fields support fractional numbers between -3.4E38 and 1.2E38.
DOUBLE–The field type will be double. Double fields support fractional numbers between -2.2E308 and 1.8E308.
TEXT–The field type will be text. Text fields support a string of characters.
DATE–The field type will be date. Date fields support date and time values.
DATEONLY–The field type will be date only. Date only fields support date values with no time values.
TIMEONLY–The field type will be time only. Time only fields support time values with no date values.
TIMESTAMPOFFSET–The field type will be timestamp offset. Timestamp offset fields support a date, time, and offset from a UTC value.
BLOB–The field type will be BLOB. BLOB fields support data stored as a long sequence of binary numbers. You need a custom loader or viewer or a third-party application to load items into a BLOB field or view the contents of a BLOB field.
GUID–The field type will be GUID. GUID fields store registry-style strings consisting of 36 characters enclosed in curly brackets.
RASTER–The field type will be raster. Raster fields can store raster data in or alongside the geodatabase. All ArcGIS software-supported raster dataset formats can be stored, but it is recommended that only small images be used.
New Field Length–The new length of the field. This sets the maximum number of allowable characters for each record of the field. This option is only applicable to fields of type Text or Blob. If the table is empty, the field length can be increased or decreased. If the table is not empty, the length can only be increased from the current value.
New Field IsNullable–Specifies whether the field can contain null values.
Clear Alias–Specifies whether the alias for the input field will be cleared.
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Value Table
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Производные выходные данные
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Имя
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Объяснение
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Тип данных
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out_table
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Обновленная входная таблица.
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Table View; Raster Layer; Mosaic Layer
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Пример кода
AlterFields, пример 1 (автономный скрипт)
Следующий автономный скрипт демонстрирует, как использовать функцию AlterFields для изменения псевдонимов полей в классе пространственных объектов.
import arcpy
test_class = arcpy.management.CreateFeatureclass(out_gdb, "new_fc", geometry_type='POLYGON')
field_description = [
['SHORT_FIELD', 'SHORT', 'SHORT_FIELD_Alias', '#', '#', '#'],
['LONG_FIELD', 'LONG', 'LONG_FIELD_Alias', '#', '#', '#'],
['BIGINTEGER_FIELD', 'BIGINTEGER', 'BIGINTEGER_FIELD_Alias', '#', '#', '#'],
['FLOAT_FIELD', 'FLOAT', 'FLOAT_FIELD_Alias', '#', '#', '#'],
['DOUBLE_FIELD', 'DOUBLE', 'DOUBLE_FIELD_Alias', '#', '#', '#'],
['TEXT_FIELD', 'TEXT', 'TEXT_FIELD_Alias', '#', '#', '#'],
['DATE_FIELD', 'DATE', 'DATE_FIELD_Alias', '#', '#', '#'],
['DATEONLY_FIELD', 'DATEONLY', 'DATEONLY_FIELD_Alias', '#', '#', '#'],
['TIMEONLY_FIELD', 'TIMEONLY', 'TIMEONLY_FIELD_Alias', '#', '#', '#'],
['TIMESTAMPOFFSET_FIELD', 'TIMESTAMPOFFSET', 'TIMESTAMPOFFSET_FIELD_Alias', '#', '#', '#']
]
arcpy.management.AddFields(test_class, field_description, None)
alter_field_description = [
['SHORT_FIELD', 'SHORT_FIELD_altered', '#', '#', '#', '#'],
['LONG_FIELD', 'LONG_FIELD_altered', '#', '#', '#', '#'],
['BIGINTEGER_FIELD', 'BIGINTEGER_FIELD_altered', '#', '#', '#', '#'],
['FLOAT_FIELD', 'FLOAT_FIELD_altered', '#', '#', '#', '#'],
['DOUBLE_FIELD', 'DOUBLE_FIELD_altered', '#', '#', '#', '#'],
['TEXT_FIELD', 'TEXT_FIELD_altered', '#', '#', '#', '#'],
['DATE_FIELD', 'DATE_FIELD_altered', '#', '#', '#', '#'],
['DATEONLY_FIELD', 'DATEONLY_FIELD_altered', '#', '#', '#', '#'],
['TIMEONLY_FIELD', 'TIMEONLY_FIELD_altered', '#', '#', '#', '#'],
['TIMESTAMPOFFSET_FIELD', 'TIMESTAMPOFFSET_FIELD_altered', '#', '#', '#', '#']
]
arcpy.management.AlterFields(in_table=test_class, field_description=alter_field_description)
AlterFields, пример 2 (автономный скрипт)
Следующий автономный скрипт демонстрирует, как использовать функцию AlterFields для изменения свойства is nullable для полей в пустой таблице.
import arcpy
test_class = arcpy.management.CreateTable(out_gdb, "new_table")
field_description = [
['SHORT_FIELD', 'SHORT', 'SHORT_FIELD_Alias', '#', '#', '#'],
['LONG_FIELD', 'LONG', 'LONG_FIELD_Alias', '#', '#', '#'],
['BIGINTEGER_FIELD', 'BIGINTEGER', 'BIGINTEGER_FIELD_Alias', '#', '#', '#'],
['FLOAT_FIELD', 'FLOAT', 'FLOAT_FIELD_Alias', '#', '#', '#'],
['DOUBLE_FIELD', 'DOUBLE', 'DOUBLE_FIELD_Alias', '#', '#', '#'],
['TEXT_FIELD', 'TEXT', 'TEXT_FIELD_Alias', '#', '#', '#'],
['DATE_FIELD', 'DATE', 'DATE_FIELD_Alias', '#', '#', '#'],
['DATEONLY_FIELD', 'DATEONLY', 'DATEONLY_FIELD_Alias', '#', '#', '#'],
['TIMEONLY_FIELD', 'TIMEONLY', 'TIMEONLY_FIELD_Alias', '#', '#', '#'],
['TIMESTAMPOFFSET_FIELD', 'TIMESTAMPOFFSET', 'TIMESTAMPOFFSET_FIELD_Alias', '#', '#', '#']
]
arcpy.management.AddFields(test_class, field_description, None)
# Change the nullable property to true
alter_field_description = [
['SHORT_FIELD', '#', '#', '#','#', 'true', '#'],
['LONG_FIELD', '#', '#', '#','#', 'true', '#'],
['BIGINTEGER_FIELD', '#', '#', '#','#', 'true', '#'],
['FLOAT_FIELD', '#', '#', '#','#', 'true', '#'],
['DOUBLE_FIELD', '#', '#', '#','#', 'true', '#'],
['TEXT_FIELD', '#', '#', '#','#', 'true', '#'],
['DATE_FIELD', '#', '#', '#','#', 'true', '#'],
['DATEONLY_FIELD', '#', '#', '#','#', 'true', '#'],
['TIMEONLY_FIELD', '#', '#', '#','#', 'true', '#'],
['TIMESTAMPOFFSET_FIELD', '#', '#', '#','#', 'true', '#']
]
arcpy.management.AlterFields(in_table=test_class, field_description=alter_field_description)