How to marshal a golang struct to JSON with custom field names?
Jun 30, 2025 am 01:59 AMIn Go, if you want the structure field to use a custom field name when converting to JSON, you can implement it through the json tag of the structure field. 1. Use the json: "custom_name" tag to specify the key name of the field in JSON. For example, Name string json: "username"" will make the Name field output as "username"; 2. Add, omitempty can control the omitted output when the field is empty. For example, Email string json: "email,omitempty"" will not display the field when the Email is an empty string. Note that the "empty" judgment criteria for pointer type and numeric type are different; 3. For nested structures or anonymous fields, you can also use json tags to name it, such as structure field Address json:"address_info``` will output the content of the Address with "address_info" as the key, and the anonymous field can also be renamed through the tag. These methods cover most of the requirements of JSON serialization scenarios.
In Go, if you want the structure field to be converted to JSON, you only need to specify it using the json
tag in the structure tag. This method is simple and direct, but there are several details that need attention.

Custom field names using json
tag
Go's standard library encoding/json
will automatically read the field's json
tag when serializing the structure to determine the output key name. For example:

type User struct { Name string `json:"username"` Age int `json:"user_age"` }
In the example above, Name
field will be named "username"
when outputting JSON, and Age
will be named "user_age"
.
If you do not set the json
tag, then by default, the JSON key name is the structure field name and is in lowercase the initial letter. For example, if the field is named Email
, then the JSON output is "email"
.

Control whether to omit empty value
Sometimes you may want certain fields not to be displayed in JSON when they are empty (such as empty strings, 0, nil, etc.). At this time, you can add ,omitempty
to the json
tag:
type User struct { Name string `json:"username,omitempty"` Email string `json:"email,omitempty"` }
This way, if Email
is an empty string, it will not appear in the final JSON result.
Pay attention to the following points:
- If the field type is a pointer,
omitempty
is also supported. - For numeric types (such as
int
), a value of0
will also be ignored by omitempty, so be careful. - The criteria for "empty" judgment of different data types are slightly different, and it is necessary to judge whether it is applicable based on the actual situation.
Handle nested structures and anonymous fields
If your structure contains other structures or anonymous fields, you can also control the output field name through the tag.
For example:
type Address struct { City string `json:"city"` Zip string `json:"zip_code"` } type User struct { Name string `json:"username"` Address `json:"address_info"` }
In this example, the JSON name corresponding to Addr
field is address_info
, and the output effect is as follows:
{ "username": "tom", "address_info": { "city": "Shanghai", "zip_code": "200000" } }
If it is an anonymous structure field, the field name will be promoted to the outer structure by default. If you want to rename this embedded field, you can also use the json
tag to specify the name.
summary
Basically that's it. Just remember a few key points: use json
tags to customize the field name, combine omitempty
to control the null value output, and pay attention to the handling of nested structures. These techniques can cover most of the needs in real scenarios.
The above is the detailed content of How to marshal a golang struct to JSON with custom field names?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Golang is mainly used for back-end development, but it can also play an indirect role in the front-end field. Its design goals focus on high-performance, concurrent processing and system-level programming, and are suitable for building back-end applications such as API servers, microservices, distributed systems, database operations and CLI tools. Although Golang is not the mainstream language for web front-end, it can be compiled into JavaScript through GopherJS, run on WebAssembly through TinyGo, or generate HTML pages with a template engine to participate in front-end development. However, modern front-end development still needs to rely on JavaScript/TypeScript and its ecosystem. Therefore, Golang is more suitable for the technology stack selection with high-performance backend as the core.

The key to installing Go is to select the correct version, configure environment variables, and verify the installation. 1. Go to the official website to download the installation package of the corresponding system. Windows uses .msi files, macOS uses .pkg files, Linux uses .tar.gz files and unzip them to /usr/local directory; 2. Configure environment variables, edit ~/.bashrc or ~/.zshrc in Linux/macOS to add PATH and GOPATH, and Windows set PATH to Go in the system properties; 3. Use the government command to verify the installation, and run the test program hello.go to confirm that the compilation and execution are normal. PATH settings and loops throughout the process

To build a GraphQLAPI in Go, it is recommended to use the gqlgen library to improve development efficiency. 1. First select the appropriate library, such as gqlgen, which supports automatic code generation based on schema; 2. Then define GraphQLschema, describe the API structure and query portal, such as defining Post types and query methods; 3. Then initialize the project and generate basic code to implement business logic in resolver; 4. Finally, connect GraphQLhandler to HTTPserver and test the API through the built-in Playground. Notes include field naming specifications, error handling, performance optimization and security settings to ensure project maintenance

sync.WaitGroup is used to wait for a group of goroutines to complete the task. Its core is to work together through three methods: Add, Done, and Wait. 1.Add(n) Set the number of goroutines to wait; 2.Done() is called at the end of each goroutine, and the count is reduced by one; 3.Wait() blocks the main coroutine until all tasks are completed. When using it, please note: Add should be called outside the goroutine, avoid duplicate Wait, and be sure to ensure that Don is called. It is recommended to use it with defer. It is common in concurrent crawling of web pages, batch data processing and other scenarios, and can effectively control the concurrency process.

Using Go's embed package can easily embed static resources into binary, suitable for web services to package HTML, CSS, pictures and other files. 1. Declare the embedded resource to add //go:embed comment before the variable, such as embedding a single file hello.txt; 2. It can be embedded in the entire directory such as static/*, and realize multi-file packaging through embed.FS; 3. It is recommended to switch the disk loading mode through buildtag or environment variables to improve efficiency; 4. Pay attention to path accuracy, file size limitations and read-only characteristics of embedded resources. Rational use of embed can simplify deployment and optimize project structure.

The core of audio and video processing lies in understanding the basic process and optimization methods. 1. The basic process includes acquisition, encoding, transmission, decoding and playback, and each link has technical difficulties; 2. Common problems such as audio and video aberration, lag delay, sound noise, blurred picture, etc. can be solved through synchronous adjustment, coding optimization, noise reduction module, parameter adjustment, etc.; 3. It is recommended to use FFmpeg, OpenCV, WebRTC, GStreamer and other tools to achieve functions; 4. In terms of performance management, we should pay attention to hardware acceleration, reasonable setting of resolution frame rates, control concurrency and memory leakage problems. Mastering these key points will help improve development efficiency and user experience.

It is not difficult to build a web server written in Go. The core lies in using the net/http package to implement basic services. 1. Use net/http to start the simplest server: register processing functions and listen to ports through a few lines of code; 2. Routing management: Use ServeMux to organize multiple interface paths for easy structured management; 3. Common practices: group routing by functional modules, and use third-party libraries to support complex matching; 4. Static file service: provide HTML, CSS and JS files through http.FileServer; 5. Performance and security: enable HTTPS, limit the size of the request body, and set timeout to improve security and performance. After mastering these key points, it will be easier to expand functionality.

The purpose of select plus default is to allow select to perform default behavior when no other branches are ready to avoid program blocking. 1. When receiving data from the channel without blocking, if the channel is empty, it will directly enter the default branch; 2. In combination with time. After or ticker, try to send data regularly. If the channel is full, it will not block and skip; 3. Prevent deadlocks, avoid program stuck when uncertain whether the channel is closed; when using it, please note that the default branch will be executed immediately and cannot be abused, and default and case are mutually exclusive and will not be executed at the same time.
