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Go struct tags

Go struct tags are metadata annotations attached to struct fields that allow developers to define how the fields are treated by external packages, such as during encoding or decoding operations^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md].

Syntax

Struct tags are defined as string literals placed immediately after the type declaration within a struct definition^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md]. They are typically formatted as key-value pairs, often enclosed in backticks^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md].

type video struct {
    Id          string `json:"id"`
    Title       string `json:"title"`
    Description string `json:"description"`
    Imageurl    string `json:"imageurl"`
    Url         string `json:"url"`
}
^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md]

Mapping Fields

The primary use case for struct tags is to map struct fields to specific keys in data formats like JSON^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md].

By default, Go's standard library packages (like encoding/json) often match struct fields to data keys based on identical naming^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md]. However, when exact matches are not possible or desired—such as when the external keys use different casing (e.g., lowercase id vs. uppercase Id)—struct tags explicitly tell the Go application how to map the data correctly^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md].

For instance, the tag json:"id" ensures that the struct field Id is correctly associated with the JSON key "id", regardless of the casing difference^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md].

  • [[Go structs]]
  • [[JSON marshaling]]
  • [[Data serialization]]

Sources

^[400-devops__09-Scripting-Language__golang__introduction__part-2.json__readme.md]