RootMode.js

import { Model} from 'objection';

export default class RootModel extends Model {
  static get generateGraphSchema(){
    const required = {}, relations = {},convertType = (type) => {
      switch (type) {
        case 'string': return 'String';
        case 'integer': return 'Int';
        case 'number': return 'Float';
        case 'boolean': return 'Boolean';
        default: return 'i will throw error';
      }
    };
    let typeDef = `type ${this.name} {`;

    Object.keys(this.jsonSchema.required).forEach(k=>required[this.jsonSchema.required[k]]=true);
    Object.keys(this.relationMappings).forEach(k=>{
            let relation = this.relationMappings[k];
            if(relation.relation === this.HasManyRelation || relation.relation === this.ManyToManyRelation)
              relations[k]=`[${relation.modelClass.name}]`;
            else
              relations[k]=`${relation.modelClass.name}`;
    });
    Object.keys(this.jsonSchema.properties).forEach(k=>{
      if (!relations.hasOwnProperty(k)) {
        let type = this.jsonSchema.properties[k].type;

        if(k==='id')
         typeDef+=`${k}: ID!`;
        else
         typeDef+=`${k}: ${convertType(type)}`;

        if(required.hasOwnProperty(k))
         typeDef+='!';

        typeDef+=' ';
      }
    });
    Object.keys(relations).forEach(k=>{
          typeDef+=`${k}: ${relations[k]}`;
          if(required.hasOwnProperty(k) || required.hasOwnProperty(k+'Id'))
            typeDef+='!';
          typeDef+=' ';
    });

    typeDef+='}';
    return typeDef;
  }
}