Thanks to comwrap GmbH for contributing this topic!

Step 1. Plan the product

To create a configurable product programmatically, you'll need to know the following:

The attribute names and values defined in the attribute set assigned to the configurable product.
The category numbers assigned to the configurable product.
Which attributes to use as the configuration options.
Since this tutorial uses the sample data, we can take advantage of the options that the Top attribute set provides. This attribute set contains attributes that describe the fabric, sleeve length, and other characteristics that are specific to clothing. It also includes EAV attributes such as size and color, which are commonly available to all types of physical products.
The size of the t-shirt will be the configurable aspect of this product. Therefore, we'll create a simple product for each size (Small, Medium, and Large).

Define product characteristics

The following table lists the general characteristics of the men's t-shirt we're creating. These items are among those listed on the New Product page in Admin when the Top attribute set is selected.

Characteristic	Description
Attribute Set	Top
Product Name	Champ Tee
SKU	MS-Champ
Price	25.00
Tax Class	Taxable Goods
Weight	0.5
Categories	Men, Tops, Tees
Visibility	Catalog, Search
Material	LumaTech
Pattern	Graphic Print
Color	Gray
Size	Configurable in small, medium, or large
Description	The Champ Tee keeps you cool and dry while you do your thing. Let everyone know who you are by adding your name on the back for only $10.

A merchant typically provides the product name, SKU, price, weight, and description. The other characteristics are defined by the system.

Find the system-defined values

We'll make several calls to find the values needed to create the product

Get the attribute set ID

The sample data provides multiple attribute sets, including Default, Top, and Bottom. To assign the Top attribute set to the product, we need to know the corresponding attribute_set_id.

Use the following call to search for the attribute set named Top.

Endpoint:

GET <host>/rest/<store_code>/V1/eav/attribute-sets/list?
searchCriteria[filter_groups][0][filters][0][field]=attribute_set_name&
searchCriteria[filter_groups][0][filters][0][value]=Top&
searchCriteria[filter_groups][0][filters][0][condition_type]=eq
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GET <host>/rest/<store_code>/V1/eav/attribute-sets/list?
searchCriteria[filter_groups][0][filters][0][field]=attribute_set_name&
searchCriteria[filter_groups][0][filters][0][value]=Top&
searchCriteria[filter_groups][0][filters][0][condition_type]=eq

Response:

The attribute_set_id for the Top attribute set is 9.

{
   "items": [
       {
           "attribute_set_id": 9,
           "attribute_set_name": "Top",
           "sort_order": 0,
           "entity_type_id": 4
       }
   ],
   "search_criteria": {
       "filter_groups": [
           {
               "filters": [
                   {
                       "field": "attribute_set_name",
                       "value": "Top",
                       "condition_type": "eq"
                   }
               ]
           }
       ]
   },
   "total_count": 1
}
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{
   "items": [
       {
           "attribute_set_id": 9,
           "attribute_set_name": "Top",
           "sort_order": 0,
           "entity_type_id": 4
       }
   ],
   "search_criteria": {
       "filter_groups": [
           {
               "filters": [
                   {
                       "field": "attribute_set_name",
                       "value": "Top",
                       "condition_type": "eq"
                   }
               ]
           }
       ]
   },
   "total_count": 1
}

Get the list of attributes defined in an attribute searchCriteria

Use the GET V1/products/attribute-sets/:attributeSetId/attributes call to return information about the attributes defined in the Top attribute set.

Endpoint:

GET <host>/rest/default/V1/products/attribute-sets/9/attributes

Response:

The response contains almost 3,000 lines. The following table provides a summary of the attributes that are relevant in this tutorial.

Admin label	Selected value	Attribute ID	attribute_code	Attribute value
Tax Class	Taxable Goods	132	`tax_class_id`	2
Visibility	Catalog, Search	99	`visibility`	4
Material	LumaTech	136	`material`	148
Pattern	Graphic Print	152	`pattern`	196
Color	Gray	93	`color`	52
Size	Not applicable	141	`size`	168 (small), 169 (medium), 170 (large)

The attribute ID and value numbers might be different on your installation. Check the values carefully before using them in your calls.

Get the list of category values

You must assign the product to one or more categories to enable customers to find the product by browsing. We'll assign the Champ Tee to the Men, Tops, and Tees categories.

Use the following call to search for all categories (id is greater than or equal to 0).

GET <host>/rest/default/V1/categories?
searchCriteria[filter_groups][0][filters][0][field]=id&
searchCriteria[filter_groups][0][filters][0][value]=1&
searchCriteria[filter_groups][0][filters][0][condition_type]=gte
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GET <host>/rest/default/V1/categories?
searchCriteria[filter_groups][0][filters][0][field]=id&
searchCriteria[filter_groups][0][filters][0][value]=1&
searchCriteria[filter_groups][0][filters][0][condition_type]=gte