Defaults Deep

Defaults Deep | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Data Processing
Input types: textarea
Output type: text
Sample coverage: 4
API ready: Yes

Overview

Defaults Deep allows you to recursively merge default values into your JSON objects using the lodash _.defaultsDeep method, ensuring your data structures are complete without overwriting existing defined properties.

When to use

When you need to populate missing configuration settings in a nested JSON object.
When merging user-provided input with a set of required system defaults.
When you want to ensure specific keys exist in a data structure while preserving current values.

How it works

1Input your primary target object containing your current data.
2Provide one or more source objects containing the default values you wish to apply.
3The tool recursively traverses the objects, assigning values from the sources only where the target property is undefined.
4Receive the merged JSON object with all missing nested properties filled in.

Use cases

Standardizing API request payloads by injecting missing default parameters.
Merging user-defined application settings with factory-default configurations.
Preparing complex data structures for database insertion by ensuring all required fields are present.

Examples

1. Merging Application Settings

Frontend Developer

Background

An application has a user-defined theme object that might be missing certain nested color or spacing properties.

Problem

The UI breaks when expected nested properties are missing from the user's saved configuration.

How to use

Paste the user's partial configuration into the Target Object field and the full theme schema into Source 1.

Target: {"theme": {"primary": "blue"}} | Source 1: {"theme": {"primary": "red", "spacing": "10px"}}

Outcome

The result is {"theme": {"primary": "blue", "spacing": "10px"}}, preserving the user's primary color while adding the missing spacing.

2. API Payload Normalization

Backend Engineer

Background

Incoming requests from a client are missing several optional fields that the backend service requires to function correctly.

Problem

The service logic fails because it expects a complete object structure.

How to use

Use the incoming request as the Target Object and a template of default values as Source 1.

FAQ

Does this tool overwrite existing values?

No, it only assigns values to properties that are currently undefined in the target object.

Can it handle deeply nested objects?

Yes, the tool uses lodash _.defaultsDeep, which performs a recursive merge across all levels of the object hierarchy.

What happens if a property is null?

Since null is a defined value, the tool will not overwrite it with the default value.

How many source objects can I provide?

You can provide up to three source objects to merge into your target object.

Is the output valid JSON?

Yes, the tool returns a clean, valid JSON string representing the merged object.

Target: {"settings": {"notifications": true}} | Source 1: {"settings": {"notifications": false, "theme": "dark"}}

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Inputs

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Merging Application Settings

2. API Payload Normalization

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