Azure search allows for an array of strings to be stored against a record.
You can set up the field either by creating it directly in the azure portal, or creating a property and adding the following attributes.
[IsSearchable, IsFilterable, IsFacetable]
public string[] Category { get; set; }
The IsFilterable must be set, otherwise the framework will throw an exception
The .net SDK gives the option to set search parameters when making a query which translates into a HTTP request using the oData syntax.
https://docs.microsoft.com/en-us/rest/api/searchservice/odata-expression-syntax-for-azure-search
The documentation shows how to find a single item in the list, but not multiple options in the same list. To search for options 1 or 2 or 3 in the Category property, the filter will need to be formed as follows
$filter=(category/any(c: c eq '1') or category/any(c: c eq '2') or category/any(c: c eq '2'))
