Checking if AX column (field) exists on table in SQL

I recently saw use of DictTable.fieldName2Id to check if a field exists on a X++ table. If the method returned 0, it was assumed that the field was not found on the table.

This is, in fairness, a fine approach in most cases. However, for fields that have their field ids hardcoded (system fields, such as RecId and DataAreaId) the field id will not be 0.

A robust check if a field exists in the database for a table is to grab the DictField for that table and field combination and call DictField.isSql() method, which checks to see that the field does in fact exist on the table.

fieldName2Id-approach

fieldExistsOnTableOrIsSystemField("MyTable", "RecId")   // => always true, since `RecId` is a system-field with a hardcoded field id
fieldExistsOnTableOrIsSystemField("MyTable", "MyField") // => true if the field exists on the table in metadata

static boolean fieldExistsOnTableOrIsSystemField(str _tableName, str _fieldName)
{
    DictTable targetDictTable = new DictTable(tableName2Id(_tableName));
    FieldId fieldId = targetDictTable.fieldName2Id(_fieldName);

    return fieldId > 0;
}

isSql-approach

fieldExistsOnTable("MyTable", "RecId")   // => true if the field exists on the table in SQL
fieldExistsOnTable("MyTable", "MyField") // => true if the field exists on the table in SQL

static boolean fieldExistsOnTable(str _tableName, str _fieldName)
{
    DictTable targetDictTable = new DictTable(tableName2Id(_tableName));
    FieldId fieldId = targetDictTable.fieldName2Id(_fieldName);
    DictField field = targetDictTable.Fieldobject(fieldId);

    return field.isSql();
}