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Structured output allows you to define a JSON schema that constrains the LLM’s response format. This ensures consistent, validated outputs that are easier to parse and integrate into your applications.

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Overview

With structured output, you can specify the exact structure you want the model to return, including:
  • Required and optional fields
  • Data types for each field
  • Nested objects and arrays
  • Enumerations and constraints

​
Configuring Structured Output

Structured output is configured using the Text parameter in your request. You provide a JSON schema that defines the expected output structure. 
import (
    "github.com/curaious/uno/pkg/llm/responses"
    "github.com/curaious/uno/internal/utils"
)

// Define your JSON schema
schema := map[string]any{
    "type": "object",
    "properties": map[string]any{
        "name": map[string]any{
            "type":        "string",
            "description": "The person's name",
        },
        "age": map[string]any{
            "type":        "integer",
            "description": "The person's age",
        },
        "email": map[string]any{
            "type":        "string",
            "format":      "email",
            "description": "The person's email address",
        },
    },
    "required": []string{"name", "age"},
}

request := &responses.Request{
    Input: responses.InputUnion{
        OfString: utils.Ptr("Extract information about John Doe, age 30, email: john@example.com"),
    },
    Parameters: responses.Parameters{
        Text: &responses.TextFormat{
            Format: map[string]any{
                "type":   "json_schema",
                "name":   "structured_output",
                "strict": false,
                "schema": schema,
            },
        },
    },
}

​
Example: Extracting Structured Data

Here’s a complete example that extracts structured information from unstructured text: 
import (
    "context"
    "encoding/json"
    "fmt"
    "github.com/curaious/uno/pkg/llm/responses"
    "github.com/curaious/uno/internal/utils"
)

func main() {
    // ... client and model initialization ...

    // Define schema for extracting contact information
    contactSchema := map[string]any{
        "type": "object",
        "properties": map[string]any{
            "contacts": map[string]any{
                "type": "array",
                "items": map[string]any{
                    "type": "object",
                    "properties": map[string]any{
                        "name": map[string]any{
                            "type": "string",
                        },
                        "phone": map[string]any{
                            "type": "string",
                        },
                        "email": map[string]any{
                            "type": "string",
                        },
                    },
                    "required": []string{"name"},
                },
            },
        },
        "required": []string{"contacts"},
    }

    resp, err := model.NewResponses(context.Background(), &responses.Request{
        Instructions: utils.Ptr("You are a data extraction assistant. Extract contact information from the given text."),
        Input: responses.InputUnion{
            OfString: utils.Ptr("Contact John at 555-1234 or john@example.com, and Sarah at 555-5678."),
        },
        Parameters: responses.Parameters{
            Text: &responses.TextFormat{
                Format: map[string]any{
                    "type":   "json_schema",
                    "name":   "structured_output",
                    "strict": false,
                    "schema": contactSchema,
                },
            },
        },
    })
    if err != nil {
        panic(err)
    }

    // Parse the structured output
    for _, output := range resp.Output {
        if output.OfOutputMessage != nil {
            for _, content := range output.OfOutputMessage.Content {
                if content.OfOutputText != nil {
                    var result map[string]any
                    if err := json.Unmarshal([]byte(content.OfOutputText.Text), &result); err == nil {
                        fmt.Printf("Extracted data: %+v\n", result)
                    }
                }
            }
        }
    }
}

​
Schema Format

The schema follows the JSON Schema specification. Key components:

​
Basic Types

// String
"name": map[string]any{
    "type": "string",
}

// Integer
"age": map[string]any{
    "type": "integer",
}

// Number (float)
"price": map[string]any{
    "type": "number",
}

// Boolean
"active": map[string]any{
    "type": "boolean",
}

// Array
"tags": map[string]any{
    "type": "array",
    "items": map[string]any{
        "type": "string",
    },
}

​
Nested Objects

schema := map[string]any{
    "type": "object",
    "properties": map[string]any{
        "address": map[string]any{
            "type": "object",
            "properties": map[string]any{
                "street": map[string]any{
                    "type": "string",
                },
                "city": map[string]any{
                    "type": "string",
                },
                "zip": map[string]any{
                    "type": "string",
                },
            },
        },
    },
}

​
Enumerations

"status": map[string]any{
    "type": "string",
    "enum": []string{"pending", "approved", "rejected"},
}

​
Strict vs Non-Strict Mode

The strict parameter controls how strictly the model adheres to the schema:
  • strict: false (default): The model can be more flexible and may include additional fields or slightly deviate from the schema if it helps generate better responses.
  • strict: true: The model must strictly follow the schema with no deviations.
Text: &responses.TextFormat{
    Format: map[string]any{
        "type":   "json_schema",
        "name":   "structured_output",
        "strict": true,  // Enforce strict adherence
        "schema": schema,
    },
}

​
Streaming with Structured Output

Structured output also works with streaming responses. The model will stream the JSON structure incrementally: 
stream, err := model.NewStreamingResponses(ctx, &responses.Request{
    Input: responses.InputUnion{
        OfString: utils.Ptr("Extract information from: John Doe, 30 years old"),
    },
    Parameters: responses.Parameters{
        Stream: utils.Ptr(true),
        Text: &responses.TextFormat{
            Format: map[string]any{
                "type":   "json_schema",
                "name":   "structured_output",
                "strict": false,
                "schema": schema,
            },
        },
    },
})
if err != nil {
    panic(err)
}

var fullText strings.Builder
for chunk := range stream {
    if chunk.OfOutputTextDelta != nil {
        fullText.WriteString(chunk.OfOutputTextDelta.Delta)
    }
}

// Parse the complete JSON after streaming
var result map[string]any
json.Unmarshal([]byte(fullText.String()), &result)