Setting the Nullable Property

There are 3 methods used to determine the value of nullable for a SQLAlchemy column. The first is the required property of the schema, the second is whether the column value is generated (using, for example, x-autoincrement) and the third is the nullable property of an object property or the presence of null if type is an array (consider these to be equivalent for this discussion). nullable overrides required. If required would indicate that the column is nullable but the value is generated, then it is not nullable. The following truth table shows the logic:

required	generated	property nullable	column nullable
undefined	false	undefined	True
undefined	true	undefined	False
not in list	false	undefined	True
not in list	true	undefined	False
in list	X	undefined	False
X	X	false	False
X	X	true	True

required undefined means that the required property is not defined for the schema, not in list means that the property is not in the required list and in list means that the property is in the list. property nullable undefined means that the nullable property is not defined for the property, false and true mean that nullable is set to false or true, respectively. generated false means that the column does not get automatically generated and true means that it Does. Any value marked as X means that another value takes precedence over the value in that case (for example, if property nullable is not undefined, it takes precedence over both required and generated.

Note

To be able to include whether the column is generated in determining the type in the generated models file, the x-generated extension property is recorded in the schema recorded with a model. x-generated is for internal use only and should not be relied upon as it is subject to change.

Examples

required undefined

The following schema does not have the required property which means that all columns have nullable set to True.

Employee:
  type: object
  x-tablename: employee
  properties:
    id:
      type: integer
    name:
      type: string

generated

The following schema does not have the required property but the id property is the primary key which is autoincremented. This means that the id column is not nullable but the name column is nullable.

Employee:
    type: object
    x-tablename: employee
    properties:
      id:
        type: integer
        x-primary-key: true
        x-autoincrement: true
      name:
        type: string

required defined

The following schema has the required property and lists the id object property in the list which means that id has nullable set to False and name has nullable set to True.

Employee:
    type: object
    x-tablename: employee
    properties:
      id:
        type: integer
      name:
        type: string
    required:
      - id

nullable defined

The following schema has the nullable property set to false for one of the id object property which means that id has nullable set to False and name has nullable set to True.

Employee:
    type: object
    x-tablename: employee
    properties:
      id:
        type: integer
        nullable: false
      name:
        type: string

nullable and required conflict

The following schema has the id object property in the required list but has set the nullable property of id to true which means that the id has nullable set to True.

Employee:
    type: object
    x-tablename: employee
    properties:
      id:
        type: integer
        nullable: true
      name:
        type: string
    required:
      - id