CSDL JSON¶

Parse OData Common Schema Definition Language (CSDL) JSON v4.01 metadata directly from a JSON endpoint or byte slice - no EDMX/XML required.

Quick Start¶

import (
    "context"
    "net/http"
    "github.com/jhonsferg/traverse"
)

// From a JSON byte slice:
data := []byte(`{ "northwind.model": { ... } }`)
meta, err := traverse.ParseCSDLJSON(data)

// From an io.Reader (e.g. HTTP response body):
resp, _ := http.Get("https://api.example.com/odata/$metadata")
defer resp.Body.Close()
meta, err := traverse.ParseCSDLJSONReader(resp.Body)

Auto-detection by Content-Type¶

When fetching $metadata, traverse automatically selects the parser based on the Content-Type of the response:

Content-Type	Parser
`application/xml`, `text/xml`	EDMX (XML)
`application/json`, `application/csdl+json`	CSDL JSON (`ParseCSDLJSONReader`)

If you download the metadata file manually, pick the right function based on the file contents.

API Reference¶

`ParseCSDLJSON`¶

func ParseCSDLJSON(data []byte) (*Metadata, error)

Parses a CSDL JSON document from a byte slice. Returns ErrMetadataInvalid (wrapped) if the input is empty or not valid JSON.

`ParseCSDLJSONReader`¶

func ParseCSDLJSONReader(r io.Reader) (*Metadata, error)

Streaming variant that reads from any io.Reader. Returns ErrMetadataInvalid (wrapped) if the reader is nil or the JSON is malformed.

`*Metadata`¶

Both functions return the same *Metadata type as the EDMX parser, so all subsequent API calls (query building, code generation, OpenAPI export) work identically regardless of the source format.

type Metadata struct {
    EntityTypes  []EntityType
    EntitySets   []EntitySetInfo
    Associations []Association
    Actions      []ActionInfo
    Functions    []FunctionInfo
    ComplexTypes []ComplexType
    EnumTypes    []EnumType
}

CSDL JSON vs EDMX¶

Aspect	EDMX (XML)	CSDL JSON
Format	XML	JSON
OData version	v2 and v4	v4.01 only
Content-Type	`application/xml`	`application/json`
Typical endpoint	`$metadata`	`$metadata` with `Accept: application/json`
File extension	`.xml`	`.json`

Loading metadata from a live service¶

req, _ := http.NewRequestWithContext(ctx, http.MethodGet,
    "https://api.example.com/odata/$metadata", nil)
req.Header.Set("Accept", "application/csdl+json")

resp, err := http.DefaultClient.Do(req)
// resp.Body is CSDL JSON → use ParseCSDLJSONReader
meta, err := traverse.ParseCSDLJSONReader(resp.Body)

Notes / Limitations¶

CSDL JSON v4.01 is supported. OData v2 services expose EDMX only.
Schema annotations beyond basic type information (vocabulary terms, etc.) are parsed where present; see the Vocabulary guide for details.
ErrMetadataInvalid is a sentinel that can be checked with errors.Is.