Overview of the LoanPASS SDK for Java

The SDK was designed to make LoanPASS APIs to be easily accessible with just a few lines of code. Here are the highlighted features:

• Provided both sync and async versions of the LoanPASS APIs
• Convenient builder(s) to construct API requests safely through code-generated strong types
• Convenient annotation(s) and type-safe 2-way converters:
  • Forward converter: From a (nested) POJO to an API request
  • Backward converter: From an API response to a (nested) POJO
• Utilities to:
  • Generate enum KnownEnumId from get_configuration API
  • Generate enum KnownFieldId from get_configuration API
  • Generate GraphQL schema from enum KnownEnumId

If you would like to contribute to this project, please contact [email protected]

Getting started

//Initialize LoanPass client
String api_key  = "Bearer API Key"; //Provide your LoanPass API Key
Settings config = new Settings("https://api.loanpass.io/v1", api_key);
ILoanPassClient loanpassClient = new LoanPassClient(config);

//configuration
ConfigResponse configRes = loanpassClient.getConfiguration();

//execute-summary
ExecSummaryResponse sumRes = loanpassClient.postExecSummary(sumReq);

//execute-product
ExecProductResponse prodRes = loanpassClient.postExecProduct(prodReq);

How to build a request

There are two ways to build a request:

Preferred option - Strong typed builder

With this preferred option, the builder will validate the correctness of IDs and their values.

FieldValueMapping.IBuilder fieldBuilder = new FieldValueMappingBuilder();
List<FieldValueMapping> fields = fieldBuilder
        .fieldEnum(KnownFieldId.LOAN_PURPOSE, "refinance")
        .fieldNumber(KnownFieldId.BASE_LOAN_AMOUNT, 2)
        .fieldString(KnownFieldId.STATE, "some text")
        .fieldDuration(KnownFieldId.DESIRED_LOAN_TERM, 3, DurationUnit.DAYS)
        .build();

ExecSummaryRequest.IBuilder builder = new ExecSummaryRequestBuilder();
builder.withTime(Instant.now())
        .withFields(fields);

ExecSummaryRequest request = builder.build();

Fallback option - Weak typed builder

You should only use this fallback option when your WellKnownFieldId or WellKnownEnumId is out of date. With this option, there is absolutely no checking by the builder on the correctness of the IDs and their values.

FieldValueMapping.IBuilder fieldBuilder = new FieldValueMappingBuilder();
List<FieldValueMapping> fields = fieldBuilder
        .fieldEnum("enumId", "a", "1")
        .fieldNumber("numId", 2)
        .fieldString("stId", "some text")
        .fieldDuration("durId", 3, DurationUnit.DAYS)
        .build();

ExecSummaryRequest.IBuilder builder = new ExecSummaryRequestBuilder();
builder.withTime(Instant.now())
        .withFields(fields);

ExecSummaryRequest request = builder.build();

Prerequisites of using strong typed builder

In order to build requests with strong types, you need to generate codes containing strong types of creditApplicationFields and enumerations from the result of get_configuration API. Here are the steps to generate the code:

1. Run the unit test of LoanPassClientTest.test_getConfiguration to retrieve the latest configuration.
2. Replace test/testdata/config/response_sample.json with the result above.
3. Run these 2 unit tests to generate the latest version of strong types above.
   1. EnumType2JavaGenTest
   2. FieldDef2JavaGenTest
4. Replace KnownEnumId.java and KnownFieldId.java with temp/KnownEnumId.java.codegen and temp/KnownFieldId.java.codegen generated from the previous step.

Creating a request from a (nested) POJO in a few lines of code

Creating a request using strong typed builder is good. Still, every field has to be hand drafted and most requests contain a dozen of fields. The better way to create a request in a few lines of code is to annotate your domain object model which is in turn converted into a request. Here is the unit test to demonstrate of use of Obj2FieldValueMapping.

private enum Loan_Purpose {
    PURCHASE,
    REFINANCE
}

private class AnnotatedInputNested {
    @Tag(KnownFieldId.AFTER_REPAIR_VALUE_ARV)
    private Double afterRepairValue = 88.0;
}

private class AnnotatedInput {
    @Tag(KnownFieldId.LOAN_PURPOSE)
    private Loan_Purpose loanPurpose = Loan_Purpose.REFINANCE;

    @Tag(KnownFieldId.STATE)
    private String propertyState = "CA";

    @Tag(KnownFieldId.BASE_LOAN_AMOUNT)
    private Double loanAmount = 99.0;

    @TagDuration(value = KnownFieldId.DESIRED_LOAN_TERM, unit = DurationUnit.MONTHS)
    private Double loanTerm = 11.0;

    @TagObj
    private AnnotatedInputNested nestedInput = new AnnotatedInputNested();
}

//With a few annotations above, the AnnotatedInput source object can be converted into 
//fields of a request 
AnnotatedInput source = new AnnotatedInput();
Obj2FieldValueMapping converter = new Obj2FieldValueMapping(source);
List<FieldValueMapping> result = converter.convert();

From API response to a (nested) POJO in a single line of code

A typical response of product summary or product details API contains dozens of fields. Mapping many of these fields into a (nested) POJO can be tedious and error-prone. The "productively lazy" way to do this is through annotations and FieldValueMapping2Obj.

Continuing with the sample code "Creating a request from a (nested) POJO" above,

List<FieldValueMapping> result = converter.convert();

is to be converted back to the original POJO type of AnnotatedInput in a single line of code.

AnnotatedInput pojo = FieldValueMapping2Obj.create(result, AnnotatedInput.class);

License summary

Apache 2.0