Generating explode: false for array query parameters in swagger.json using openapi 3.0.1 and .Net Core 3.1 and Swashbucle.AspNetCore.SwaggerGen

Question

I am developing some Openapi 3.0.1 APIs with .Net Core 3.1 using Swashbuckle.AspNetCore.Swagger and SwaggerGen v6.1.4. I want to build an API that receives an array query parameter; in ASP.NET Core the default call for an API like this is something like

https://someUrl/?values=valore1&values=valore2

but due to caller needs I want to accept something simpler, like

https://someUrl/?values=valore1,valore2

In other words, I want to generate a swagger.json that has an explode: false node

  parameters:
    - name: values
      in: query
      explode: false
      schema:
        type: array
        items:
          type: string

while the default is explode: true.

How can I do this? Thank you!

Marco Di Ninno · Accepted Answer · 2022-01-28 12:20:46Z

1

After some research I managed to use a custom QueryStringValueProvider:

public class QueryStringCommaSeparatedValueProvider : QueryStringValueProvider
{
    public QueryStringCommaSeparatedValueProvider(
      BindingSource bindingSource,
      IQueryCollection values,
      CultureInfo culture) : base(bindingSource, values, culture)
    { }

    public override ValueProviderResult GetValue(string key)
    {
        var result = base.GetValue(key);

        if (result == ValueProviderResult.None)
        {
            return result;
        }

        var values = result.SelectMany(r => r.Split(","));

        return new ValueProviderResult(
          new StringValues(values.ToArray()),
          Culture);
    }
}

The relative factory:

public class QueryStringCommaSeparatedValueProviderFactory : IValueProviderFactory
{
    public Task CreateValueProviderAsync(ValueProviderFactoryContext context)
    {
        if (context == null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        var query = context.ActionContext.HttpContext.Request.Query;
        if (query != null && query.Count > 0)
        {
            var valueProvider = new QueryStringCommaSeparatedValueProvider(
              BindingSource.Query,
              query,
              CultureInfo.InvariantCulture);

            context.ValueProviders.Add(valueProvider);
        }

        return Task.CompletedTask;
    }
}

... has to be inserted in Mvc options in Startup.cs:

services.AddMvc(options =>
        {
            options.ValueProviderFactories.Insert(0,
              new QueryStringCommaSeparatedValueProviderFactory());
        });

answered Jan 28, 2022 at 12:20

Marco Di Ninno

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1 Comment

Hugo Sousa Over a year ago

This was a great help for me. However, this would cause any parameter (e.g., a string parameter) with a comma to be split. I've found this article that expands on this concept further to allow this to be set for an individual parameter: github.com/filipw/…

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