AWS Glue: Cannot define an array of struct with AWS CDK

Question

I'm trying to create a glue table with a column that maps to an array of struct with a defined schema. Using the aws_glue_alpha experimental construct, definition of an array of struct is possible only via this code syntax

glue.Schema.array(
    input_string='struct',
    is_primitive=False,
)

I want to do something like

glue.Schema.array(
  glue.Schema.struct(
       columns=[...]
)    
)

How can I achieve this?

How can you explain these examples work that do exactly what I want?

Daisi · Accepted Answer · 2025-06-09 21:22:26Z

1

Currently, I don't think you can nest glue.Schema.struct() inside glue.Schema.array() directly in aws_glue_alpha . Instead, define struct schema separately, then use it in the array.

struct_schema = glue.Schema.struct([
    glue.Column(name="field1", type=glue.Schema.string),
    glue.Column(name="field2", type=glue.Schema.int),
])

array_of_struct = glue.Schema.array(struct_schema)

I believe this works with aws-glue-alpha CDK.

answered Jun 9 at 21:22

Daisi

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1 Comment

sheva Jun 9 at 21:48

What is the difference between this and directly nesting? It's the same imo. Anyway I tried it, and I still get TypeError: Schema.array() takes 1 positional argument but 2 were given

sheva · Accepted Answer · 2025-06-09 22:27:38Z

1

By inspecting the source code of the npm package, I understood what exactly is that inputString parameter. Essentially, every schema method returns a Type instance which has two properties: inputString & isPrimitive. What I tried (and worked out) is storing a struct definition in a separate variable and pass it to the array method like

glue.Schema.array(input_string=my_struct.input_string, is_primitive=my_struct.is_primitive

answered Jun 9 at 22:27

sheva

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