Graphql-ruby: How to display an array in an array?

[afuno]

Rails, GraphQL Ruby, and a field with the JSON type in the PostgreSQL table.

There are two types of records in this field:

1. ["One","Two","Three"]
2. [["One","Two","Three"]]

This is done specially. So it is necessary.

If Rails itself displays this data as it should, then gem GraphQL inside itself works correctly only with the first view.

The second view is displayed like this:

"json_field": [
    "[\"One\", \"Two\", \"Three\"]"
]

Responsible for displaying this code:

field :json_field, types[types.String]

I understand why the second option seems to grant that way, but I can not figure out how to fix it.

Help with this, please.

[rmosolgo]

The two formats may be specified like this:

field :json_field, types[types.String]
# ["One", "Two", "Three"]
# OR: 
field :json_field, types[types[types.String]]
# [["One", "Two", "Three"]]

but there is no way to specify them _together_. Here are some options I can think of:

• Make _two_ fields, one for each format

  field :shallow_strings, types[types.String] do 
  resolve ->(obj, args, ctx) {
    if obj.json_field.first.is_a?(String)
      obj.json_field 
    else 
      nil
    end
    }
  end  
  
  field :deep_strings, types[types[types.String]] do 
  resolve ->(obj, args, ctx) {
    if obj.json_field.first.is_a?(Array)
      obj.json_field 
    else 
      nil
    end
    }
  end  
  

  Then in graphql:

  my_object { 
  deep_strings
  shallow_strings
  }
  

  Then merge them in the view code

• Use an intermediary object type + union

  ShallowStrings = GraphQL::ObjectType.new 
  name "ShallowStrings" 
  field :values, types[types.String]
  end 
  
  DeepStrings = GraphQL::ObjectType.define do 
  name "DeepStrings" 
  field :values, types[types[types.String]]
  end 
  
  StringList = GraphQL::UnionType.define do 
  name "StringList" 
  possible_types [DeepStrings, ShallowStrings]
  end 
  
  # ...
  
  field :json_field, StringList
  

  Then in GraphQL:

  json_field {
    ... on ShallowStrings { values }
    ... on DeepStrings { values } 
  }
  

  This way, the resulting "values" may be of either format.

  Unions can only be created of object types.

  How do those sound?

[afuno]

@rmosolgo Your example from the first point helped me. Thank you.

The second point I did not understand. I copied your code, but in the end I get this error:

schema contains Interfaces or Unions, so you must define a 'resolve_type -> (obj, ctx) { ... }' function (NotImplementedError)

Because of this error the project falls.

Most likely the matter is that I incorrectly pass json_field in the query.

[rmosolgo]

Sorry, that error popped up because you need to define resolve_type in your schema:

http://graphql-ruby.org/types/abstract_types.html#type-resolution

[rmosolgo]

I hope that helped! Feel free to reopen with more details if you're still stuck.

[woahstorkdork]

thank you for being so helpful @rmosolgo !