129 lines
3.5 KiB
Go
129 lines
3.5 KiB
Go
// A simple Go wrapper around the OpenLibrary.org Books API
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package client
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import (
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"encoding/json"
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"fmt"
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"io"
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"net/http"
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"net/url"
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)
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var (
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defaultAPI = "https://openlibrary.org/api/books"
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)
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var (
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// FormatError marks errors with provided book identifers
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FormatError = fmt.Errorf("identifier in wrong format")
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// NetworkError marks errors with the connection to the OpenLibrary API
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NetworkError = fmt.Errorf("network error")
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// NotFoundError marks an empty response from the OpenLibrary API
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NotFoundError = fmt.Errorf("book not found")
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)
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// Client provides OpenLibrary Books API query methods
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type Client struct {
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httpClient http.Client
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apipath string
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}
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// SetHTTPClient updates the httpClient on the client with a manually-configured one.
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// If unset, the client will fall back to using http.DefaultClient.
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func (c *Client) SetHTTPClient(h http.Client) {
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c.httpClient = h
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}
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// SetAPIPath updates the hostname and path to the API; the default is "https://openlibrary.org/api/books".
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// If APIPath is set to an empty string, the client will fall back to the default option.
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func (c *Client) SetAPIPath(p string) {
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c.apipath = p
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}
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// GetByISBN fetches details for a book based on its ISBN10 or ISBN13.
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func (c *Client) GetByISBN(k string) (*BookDetails, error) {
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if k == "" {
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return nil, fmt.Errorf("%w: ISBN cannot be empty", FormatError)
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} else if len(k) != 10 && len(k) != 13 {
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return nil, fmt.Errorf("%w: ISBN must be either 10 or 13 digits", FormatError)
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}
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key := "ISBN:" + k
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return c.fetch(key)
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}
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// GetByOCLC fetches details for a book based on its WorldCat OCLC number.
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func (c *Client) GetByOCLC(k string) (*BookDetails, error) {
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if k == "" {
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return nil, fmt.Errorf("%w: OCLC cannot be empty", FormatError)
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}
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key := "OCLC:" + k
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return c.fetch(key)
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}
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// GetByLCCN fetches details for a book based on its Library of Congress Control Number.
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func (c *Client) GetByLCCN(k string) (*BookDetails, error) {
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if k == "" {
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return nil, fmt.Errorf("%w: LCCN cannot be empty", FormatError)
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}
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key := "LCCN:" + k
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return c.fetch(key)
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}
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// GetByOLID fetches details for a book based on its OpenLibrary ID number.
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func (c *Client) GetByOLID(k string) (*BookDetails, error) {
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if k == "" {
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return nil, fmt.Errorf("%w: OLID cannot be empty", FormatError)
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}
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key := "OLID:" + k
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return c.fetch(key)
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}
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// GetByRawKey fetches details for a book based on an arbitrary key; this method is provided
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// as a future-proof fallback in case the OpenLibrary API adds more "bibkey" request types in the future.
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// Most users should use one of the other lookup functions.
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func (c *Client) GetByRawKey(k string) (*BookDetails, error) {
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return c.fetch(k)
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}
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func (c *Client) fetch(key string) (*BookDetails, error) {
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h := c.apipath
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if h == "" {
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h = defaultAPI
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}
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u, err := url.Parse(h)
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if err != nil {
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return nil, fmt.Errorf("%w: %v", NetworkError, err)
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}
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u.RawQuery = url.Values{
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"bibkeys": []string{key},
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"jscmd": []string{"data"},
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"format": []string{"json"},
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}.Encode()
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resp, err := c.httpClient.Get(u.String())
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if err != nil {
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return nil, fmt.Errorf("%w: %v", NetworkError, err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("%w: received non-200 status code: %d", NetworkError, resp.StatusCode)
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}
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var result response
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b, err := io.ReadAll(resp.Body)
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if err != nil {
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return nil, fmt.Errorf("%w: %v", NetworkError, err)
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}
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if err = json.Unmarshal(b, &result); err != nil {
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return nil, fmt.Errorf("%w: %v", NetworkError, err)
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}
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details, ok := result[key]
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if !ok {
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return nil, NotFoundError
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}
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return &details, nil
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}
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