Forcing a conformant format

codescan derives a JSON-Schema type and format from each Go type. For the unsized and large integer kinds it emits Go-specific vendor formats — uint64 → {type: integer, format: uint64}, uint32 → {integer, uint32}, and so on. These round-trip cleanly back to Go, but they are not part of the Swagger 2.0 format set, and a uint64 value can exceed what a JSON number safely represents.

When you need conformant, precision-safe output, place a field-level swagger:strfmt on the field to override just that property’s format. Overriding to int64 publishes the value as a string-encoded {type: string, format: int64}:

model

// Measurement forces a JSON-conformant format on a field. A uint64 field emits
// the Go-specific `{integer, format: uint64}` by default; overriding it with a
// field-level `swagger:strfmt int64` (below) yields a precision-safe,
// string-encoded `{string, format: int64}`.
//
// swagger:model
type Measurement struct {
	// Raw keeps the default Go-derived vendor format (uint64).
	Raw uint64 `json:"raw"`

	// Bounded is forced to a conformant, string-encoded int64.
	//
	// swagger:strfmt int64
	Bounded uint64 `json:"bounded"`
}

Full source: docs/examples/shaping/formats/formats.go

#/definitions/Measurement

{
  "description": "Measurement forces a JSON-conformant format on a field. A uint64 field emits\nthe Go-specific `{integer, format: uint64}` by default; overriding it with a\nfield-level `swagger:strfmt int64` (below) yields a precision-safe,\nstring-encoded `{string, format: int64}`.",
  "type": "object",
  "properties": {
    "bounded": {
      "description": "Bounded is forced to a conformant, string-encoded int64.",
      "type": "string",
      "format": "int64",
      "x-go-name": "Bounded"
    },
    "raw": {
      "description": "Raw keeps the default Go-derived vendor format (uint64).",
      "type": "integer",
      "format": "uint64",
      "x-go-name": "Raw"
    }
  },
  "x-go-package": "github.com/go-openapi/codescan/docs/examples/shaping/formats"
}

Full source: docs/examples/shaping/formats/testdata/measurement.json

Raw keeps the default {integer, uint64} vendor format; Bounded carries swagger:strfmt int64, so it renders as a string-encoded int64. The override is per-field — the underlying Go type is untouched everywhere else.

Info

swagger:strfmt also names a custom string format on a type declaration (e.g. a UUID type → {string, format: uuid}); see Model definitions → swagger:strfmt. The swagger:type annotation is the related tool when you want to override the whole type, not just its format — see Type discovery and the swagger:type reference.