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Variables

Variables allow you to pass dynamic values to your queries and mutations, making them reusable.

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Using variables

Define variables in your query and pass them separately: 
query GetDeal($id: ID!) {
  deal(id: $id) {
    id
    status
  }
}
Variables: 
{
  "id": "123"
}

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Variable types

GraphQL supports various variable types:
  • ID! - Required ID
  • String - Optional string
  • Int - Integer
  • Float - Floating point number
  • Boolean - True/false
  • Custom input types

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Example with multiple variables

query GetDeals($first: Int, $status: DealStatus) {
  deals(first: $first, status: $status) {
    id
    status
  }
}
Variables: 
{
  "first": 10,
  "status": "ACTIVE"
}

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Fragments

Fragments allow you to reuse field selections across multiple queries.

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Basic fragment

fragment BorrowerFields on Borrower {
  id
  firstName
  lastName
  email
}

query GetDeal {
  deal(id: "123") {
    id
    borrowers {
      ...BorrowerFields
    }
  }
}

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Multiple fragments

You can use multiple fragments in a single query: 
fragment BorrowerFields on Borrower {
  id
  firstName
  lastName
}

fragment IncomeFields on Income {
  statedMonthlyAmount
  payPeriodFrequency
}

query GetDeal {
  deal(id: "123") {
    id
    borrowers {
      ...BorrowerFields
      incomes {
        ...IncomeFields
      }
    }
  }
}

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Inline fragments

Use inline fragments for union types or interfaces: 
query GetLoan {
  loan(id: "123") {
    id
    ... on ConventionalLoan {
      loanAmount
      ltv
    }
    ... on JumboLoan {
      loanAmount
      jumboLimit
    }
  }
}

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Best practices

  1. Use variables for dynamic values - Never hardcode IDs or filters
  2. Create reusable fragments - Define common field selections once
  3. Name fragments descriptively - Use clear, descriptive names
  4. Keep fragments focused - Don’t create overly large fragments

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Common patterns

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Reusable borrower fragment

fragment BorrowerDetails on Borrower {
  id
  firstName
  lastName
  email
  phoneNumber
  incomes {
    statedMonthlyAmount
    payPeriodFrequency
  }
  assets {
    amount
    institutionName
  }
}

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Using in multiple queries

query GetDeal($id: ID!) {
  deal(id: $id) {
    id
    borrowers {
      ...BorrowerDetails
    }
  }
}

query GetBorrower($id: ID!) {
  borrower(id: $id) {
    ...BorrowerDetails
  }
}