SELECT Models

The real value of the FieldResolver is its' ability to create "views" or "models" which can be used in any query to ensure that you always pull consistent data for an object.

To do so, simply create a function that accepts a FieldResolver<T> and returns a string[]

Example

const userModel = (userFields: FieldResolver<User>): string[] => {
    return userFields.select('address', 'aboutMe', 'email')
}

const accountModel = (accFields: FieldResolver<Account>): string[] => {
    return [
        ...accFields.select('accountNumber', 'active', 'billingCity'),
        ...userModel(accFields.parent('owner')),
        ...userModel(accFields.parent('lastModifiedBy'))
    ]
}

const contactModel = (contactFields: FieldResolver<Contact>): string[] => {
    return [
        ...contactFields.select('email', 'name'),
        ...accountModel(contactFields.parent('account')),
        ...userModel(contactFields.parent('owner')),
        ...userModel(contactFields.parent('lastModifiedBy')),
    ]
}

// See output in tab
let accountQuery = buildQuery(Account, cFields => (
    {
      select: accountModel(cFields),
      limit: 1
    }
));

let contactQuery = buildQuery(Contact, cFields => (
    {
      select: contactModel(cFields),
      limit: 1
    }
));

Output: accountQuery

SELECT
  AccountNumber,
  Active__c,
  BillingCity,
  Owner.Address,
  Owner.AboutMe,
  Owner.Email,
  LastModifiedBy.Address,
  LastModifiedBy.AboutMe,
  LastModifiedBy.Email
FROM
  Account
LIMIT
  1

Output: contactQuery

SELECT
  Email,
  Name,
  Account.AccountNumber,
  Account.Active__c,
  Account.BillingCity,
  Account.Owner.Address,
  Account.Owner.AboutMe,
  Account.Owner.Email,
  Account.LastModifiedBy.Address,
  Account.LastModifiedBy.AboutMe,
  Account.LastModifiedBy.Email,
  Owner.Address,
  Owner.AboutMe,
  Owner.Email,
  LastModifiedBy.Address,
  LastModifiedBy.AboutMe,
  LastModifiedBy.Email
FROM
  Contact
LIMIT
  1

Recursive Models

In some cases you might need a model that SELECTS a parent of the same type. This can be done by adding an "termination condition" that checks the traversed array in the model function:

Example

const contactViewRecursive = (contactFields: FieldResolver<Contact>): string[] => {
    if(contactFields.traversed.length == 5){
        return [];
    }
    return [
        ...contactFields.select('email', 'name'),
        ...contactViewRecursive(contactFields.parent('reportsTo'))
    ]
}
let qry = buildQuery(Contact, cFields => (
    {
      select: contactViewRecursive(cFields),
      limit: 1
    }
));

Output

SELECT
  Email,
  Name,
  ReportsTo.Email,
  ReportsTo.Name,
  ReportsTo.ReportsTo.Email,
  ReportsTo.ReportsTo.Name,
  ReportsTo.ReportsTo.ReportsTo.Email,
  ReportsTo.ReportsTo.ReportsTo.Name,
  ReportsTo.ReportsTo.ReportsTo.ReportsTo.Email,
  ReportsTo.ReportsTo.ReportsTo.ReportsTo.Name
FROM
  Contact
LIMIT
  1

Salesforce limits relationship traversals to a depth of 5