Parsing JSON is mainly implemented in the Go language through encoding/json package. Common methods include: 1. When parsing JSON to a structure, you need to define the structure that matches the field and use the json.Unmarshal function; 2. For unknown structures, you can parse to map[string]interface{} or interface{}; 3. When processing arrays, you can use structure slices or []map[string]interface{}; 4. You can ignore fields through tags, delay parsing or process missing fields. Mastering these techniques can effectively deal with most JSON parsing scenarios.
Parsing JSON is a common operation in the Go language, especially when handling API requests or configuration files. encoding/json package in Go standard library already provides very convenient tools to complete this task. As long as you master the basic usage, you can easily deal with most scenarios.
Parsing JSON to structure
When you know the specific structure of JSON data, the most common method is to parse it into a structure. This allows easy access to fields and type checking.
The steps for use are as follows:
- Define a structure whose field name and type must correspond to the key in JSON
- Parse byte slices into structure instances using
json.Unmarshalfunction - Note that the field name must start with capital letters, otherwise it cannot be exported (JSON package cannot be assigned)
Sample code:
type User struct {
Name string `json:"name"`
Age int `json:"age"`
}
data := []byte(`{"name":"Alice","age":30}`)
var user User
err := json.Unmarshal(data, &user) If the JSON field name does not match the structure field, you can use json:"xxx" tag to specify the mapping relationship.
Parse unknown structures JSON
If you don't know the specific structure of JSON, or the structure may change, you can use map[string]interface{} or interface{} to receive data.
For example, parse a JSON object with an uncertain structure:
var dataMap map[string]interface{}
err := json.Unmarshal(data, &dataMap)This approach is flexible but requires manual type assertion, such as getting the string value of a certain field:
if name, ok := dataMap["name"].(string); ok {
fmt.Println("Name:", name)
} For nested structures, you can also recursively use map or []interface{} to process arrays.
Processing JSON arrays
If JSON is an array format, for example:
[
{"name": "Alice", "age": 30},
{"name": "Bob", "age": 25}
]You can define a struct slice to receive it:
var users []User err := json.Unmarshal(data, &users)
Similarly, you can also use []map[string]interface{} to handle array contents with unfixed structures.
Tips: Ignore unwanted fields or tolerate errors
In actual development, sometimes JSON will contain some fields that we do not need, or the field types may be inconsistent. At this time, fault tolerance can be improved by the following methods:
Use
_unwanted fields:type User struct { Name string `json:"name"` _ int `json:"-"` }Delayed parsing nested structures using
json.RawMessageUse
omitemptyto control whether the field is empty and not serializedIf the field may be missing, make sure it is of a pointer or a nullable type (such as
*string)
Basically that's it. Although Go's JSON parsing mechanism is not as flexible as dynamic languages, type safety and compile-time checking can help you avoid many runtime errors. Mastering structure mapping, generic parsing and common label usage will be able to deal with most situations.
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