Schema Customization - Allow removing unused fields and types of input objects

[gils]

Use case

First - I would like to take a moment to thank all the people who help maintain and support this project. Thank you!

The problem I'm dealing with is when the server generated schema contains input objects with tons of optional parameters (which could in turn have nested types) of which the application code only needs a few.

The end result is bloated generated input objects out of which only a small portion is ever needed by the application.

The trivial solution is to rewrite the query / mutation to pass only the selected parameters into the input object - which adds those parameters as variables to the generated operation.

There are a few disadvantages to the trivial approach:

1. We don't get auto-generated code comments on the input variables
2. The variables are coupled with the operation and can't be reused by other queries / mutations
3. There could be nested input object types which can also contain redundant parameters. Those can't be customized at the operation level.

So the ask is to enhance the code generator configuration to allow specifying the desired fields of selected input objects. This customization can help reduce the amount of code generated where a specific application doesn't need it.

Describe the solution you'd like

Looking at https://www.apollographql.com/docs/ios/code-generation/codegen-configuration#schema-customization

One solution could be updating the fields mapping to be [String: String?] and fields with null values will be removed from the generated code.

"MyInputObject" : {
        "inputObject" : {
          "fields" : {
            "myField" : "customField",
            "bloatedField": null
          },
          "name" : "CustomInputObject"
        }
      }

If we assume bloatedField is another object which is only used in this input object - then this small change could result in multiple types not needing to be generated.

Similarly we can specify any input object we need, even when it's nested deep in the schema.

[BobaFetters]

@gils We currently have an option to reduceGeneratedSchemaTypes which can prevent entire types from being generated if they aren't used. However, the level of control you mentioned isn't something we are likely to add to the library. That level of control over individual fields should really be handled as part of the schema design.

[github-actions]

Do you have any feedback for the maintainers? Please tell us by taking a one-minute survey. Your responses will help us understand Apollo iOS usage and allow us to serve you better.

[gils]

@gils We currently have an option to reduceGeneratedSchemaTypes which can prevent entire types from being generated if they aren't used. However, the level of control you mentioned isn't something we are likely to add to the library. That level of control over individual fields should really be handled as part of the schema design.

Understood. Thanks for the quick response.
Unfortunately - reducegeneratedschematypes doesn't solve this case.

[martinbonnin]

@gils you may be able to "pre-process" your schema to remove the unneeded input fields. One example of a similar question is there: ardatan/graphql-tools#1058.

Not sure if there is an out of the box solution but if you know some input fields are never going to be set (and are not required), you can probably just remove them.