---
title: "MapMissingFieldsFromTable"
slug: "mapmissingfieldsfromtable"
updated: 2022-05-17T16:13:19Z
published: 2022-05-17T16:13:19Z
canonical: "docs.datajet.app/mapmissingfieldsfromtable"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.datajet.app/llms.txt
> Use this file to discover all available pages before exploring further.

# MapMissingFieldsFromTable

Used when standardising variable data input sources to a specific data model. This can be necessary if fieldnames are variable and/or data may be missing in an input file but the script needs to process the file anyway. The method assumes that a mapping table has been created that has a list of expected standardised field names which must exist for some part of the script to work (stored in this example in the [01_DATA_MAPPING].[DATAMODEL] field, and referenced by the method as “targetField”).

The method can work directly with the DATAMODEL field (in which case sourceField would be DATAMODEL) or it can use a lookup field (for example ExportField), in which case sourceField would be ExportField. This can be helpful if outputs from the script are also variable. The logic is as follows:

For each value X of sourceField on table sourceTable: if not blank: get targetField Y on table sourceTable If Y does not exist on targetTable Make Y on targetTable

{ "method": "MapMissingFieldsFromTable", "description": "Create Missing Fields required for Export Template", "sourceTable": "01_DATA_MODEL", "sourceField": "ExportField", "targetField": "DATAMODEL", "typeField": "Data Type", "targetTable": "02_TRANSFORMS", "makeValidFieldNames": true, "project": "DATA_MAPPING" } For example: DATAMODEL ExportField DataType DATAMODEL_VALUE Product Value String DATAMODEL_NAME Product Name String DATAMODEL_ID Product ID String DATAMODEL_PLACE String DATAMODEL_DATE Purchase Date Date For the data above, assuming non DATAMODEL_X fields exist on the target table, the following fields would be created: DATAMODEL_VALUE DATAMODEL_NAME DATAMODEL_ID DATAMODEL_DATE Created fields are filled with NULL data.