Function remapObject

  • remapObject<DataType extends Record<string, unknown>>(
        data: DataType,
        mapping: ObjectMapping<DataType>,
    ): DataType

    Remaps an object by applying field mappings while preserving original data.

    This function takes your original data object and a mapping configuration, then returns a new object that contains:

    • All original fields from the input data
    • Additional/overridden fields based on the mapping

    The mapping allows you to extract values using:

    • Simple property names: "fieldName"
    • Dot notation: "user.profile.name"
    • Array access: "items[0].id"
    • JSONPath expressions: "$.items[*].id"
    • Function extractors: (data) => data.customField

    Type Parameters

    • DataType extends Record<string, unknown>

    Parameters

    Returns DataType

    A new object with original fields plus mapped fields

    Example

    Basic remapping:

    const data = {
      name: "John",
      age: 30,
      email: "john@example.com",
    };

    const mapping: ObjectMapping<typeof data> = {
      userName: "name",
      userAge: "age",
    };

    const result = remapObject(data, mapping);
    // Result: {
    //   name: "John",
    //   age: 30,
    //   email: "john@example.com",
    //   userName: "John",      // Added from mapping
    //   userAge: 30,            // Added from mapping
    // }

    Example

    Nested property extraction:

    const data = {
      user: {
        profile: {
          firstName: "John",
          lastName: "Doe",
        },
        email: "john@example.com",
      },
    };

    const mapping: ObjectMapping<typeof data> = {
      firstName: "user.profile.firstName",
      lastName: "user.profile.lastName",
      email: "user.email",
    };

    const result = remapObject(data, mapping);
    // Result includes original data plus:
    // {
    //   firstName: "John",
    //   lastName: "Doe",
    //   email: "john@example.com",
    // }

    Example

    Array element access:

    const data = {
      items: [
        { id: 1, name: "Apple" },
        { id: 2, name: "Banana" },
      ],
    };

    const mapping: ObjectMapping<typeof data> = {
      firstItemId: "items[0].id",
      firstItemName: "items[0].name",
    };

    const result = remapObject(data, mapping);
    // Result includes:
    // {
    //   firstItemId: 1,
    //   firstItemName: "Apple",
    // }

    Example

    Function-based transformation:

    const data = {
      firstName: "John",
      lastName: "Doe",
      scores: [85, 92, 78],
    };

    const mapping: ObjectMapping<typeof data> = {
      fullName: (data) => `${data.firstName} ${data.lastName}`,
      averageScore: (data) =>
        data.scores.reduce((a, b) => a + b, 0) / data.scores.length,
    };

    const result = remapObject(data, mapping);
    // Result includes:
    // {
    //   fullName: "John Doe",
    //   averageScore: 85,
    // }

    Example

    Field override:

    const data = {
      name: "John",
      status: "inactive",
    };

    const mapping: ObjectMapping<typeof data> = {
      // Override existing field
      status: (data) => data.name === "John" ? "active" : "inactive",
      // Add new field
      displayName: (data) => `User: ${data.name}`,
    };

    const result = remapObject(data, mapping);
    // Result:
    // {
    //   name: "John",
    //   status: "active",        // Overridden
    //   displayName: "User: John", // Added
    // }

    Example

    Real-world evaluator usage:

    // Your data structure
    const example = {
      question: "What is AI?",
      context: "AI is artificial intelligence...",
      answer: "AI stands for artificial intelligence",
    };

    // Evaluator expects: { input, reference, output }
    const mapping: ObjectMapping<typeof example> = {
      input: "question",
      reference: "context",
      output: "answer",
    };

    const remapped = remapObject(example, mapping);
    // Now remapped has: { question, context, answer, input, reference, output }
    // The evaluator can access input, reference, and output fields

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