ResolveChoice class

Resolves a choice type within a DynamicFrame.

Example

We recommend that you use the DynamicFrame.resolveChoice() method to handle fields that contain multiple types in a DynamicFrame. To view a code example, see Example: Use resolveChoice to handle a column that contains multiple types.

Methods

• __call__

• apply

• name

• describeArgs

• describeReturn

• describeTransform

• describeErrors

• describe

__call__(frame, specs = none, choice = "", transformation_ctx = "", info = "", stageThreshold = 0, totalThreshold = 0)

Provides information for resolving ambiguous types within a DynamicFrame. It returns the resulting DynamicFrame.

• frame – The DynamicFrame in which to resolve the choice type (required).

• specs – A list of specific ambiguities to resolve, each in the form of a tuple: (path, action). The path value identifies a specific ambiguous element, and the action value identifies the corresponding resolution.

  You can only use one of the spec and choice parameters. If the spec parameter is not None, then the choice parameter must be an empty string. Conversely, if the choice is not an empty string, then the spec parameter must be None. If neither parameter is provided, AWS Glue tries to parse the schema and use it to resolve ambiguities.

  You can specify one of the following resolution strategies in the action portion of a specs tuple:

  • cast – Allows you to specify a type to cast to (for example, cast:int).

  • make_cols – Resolves a potential ambiguity by flattening the data. For example, if columnA could be an int or a string, the resolution is to produce two columns named columnA_int and columnA_string in the resulting DynamicFrame.

  • make_struct – Resolves a potential ambiguity by using a struct to represent the data. For example, if data in a column could be an int or a string, using the make_struct action produces a column of structures in the resulting DynamicFrame with each containing both an int and a string.

  • project – Resolves a potential ambiguity by retaining only values of a specified type in the resulting DynamicFrame. For example, if data in a ChoiceType column could be an int or a string, specifying a project:string action drops values from the resulting DynamicFrame that are not type string.

  If the path identifies an array, place empty square brackets after the name of the array to avoid ambiguity. For example, suppose you are working with data structured as follows:

  "myList": [
    { "price": 100.00 },
    { "price": "$100.00" }
  ]

  You can select the numeric rather than the string version of the price by setting the path to "myList[].price", and setting the action to "cast:double".

• choice – The default resolution action if the specs parameter is None. If the specs parameter is not None, then this must not be set to anything but an empty string.

  In addition to the specs actions previously described, this argument also supports the following action:

  • MATCH_CATALOG – Attempts to cast each ChoiceType to the corresponding type in the specified Data Catalog table.

• database – The AWS Glue Data Catalog database to use with the MATCH_CATALOG choice (required for MATCH_CATALOG ).

• table_name – The AWS Glue Data Catalog table name to use with the MATCH_CATALOG action (required for MATCH_CATALOG ).

• transformation_ctx – A unique string that is used to identify state information (optional).

• info – A string associated with errors in the transformation (optional).

• stageThreshold – The maximum number of errors that can occur in the transformation before it errors out (optional). The default is zero.

• totalThreshold – The maximum number of errors that can occur overall before processing errors out (optional). The default is zero.

apply(cls, *args, **kwargs)

Inherited from GlueTransform apply.

name(cls)

Inherited from GlueTransform name.

describeArgs(cls)

Inherited from GlueTransform describeArgs.

describeReturn(cls)

Inherited from GlueTransform describeReturn.

describeTransform(cls)

Inherited from GlueTransform describeTransform.

describeErrors(cls)

Inherited from GlueTransform describeErrors.

describe(cls)

Inherited from GlueTransform describe.