68 lines
1.8 KiB
Go
68 lines
1.8 KiB
Go
package pagination
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import "fmt"
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// LinkedPageBase may be embedded to implement a page that provides navigational "Next" and "Previous" links within its result.
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type LinkedPageBase struct {
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PageResult
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// LinkPath lists the keys that should be traversed within a response to arrive at the "next" pointer.
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// If any link along the path is missing, an empty URL will be returned.
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// If any link results in an unexpected value type, an error will be returned.
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// When left as "nil", []string{"links", "next"} will be used as a default.
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LinkPath []string
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}
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// NextPageURL extracts the pagination structure from a JSON response and returns the "next" link, if one is present.
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// It assumes that the links are available in a "links" element of the top-level response object.
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// If this is not the case, override NextPageURL on your result type.
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func (current LinkedPageBase) NextPageURL() (string, error) {
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var path []string
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var key string
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if current.LinkPath == nil {
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path = []string{"links", "next"}
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} else {
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path = current.LinkPath
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}
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submap, ok := current.Body.(map[string]interface{})
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if !ok {
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return "", fmt.Errorf("Expected an object, but was %#v", current.Body)
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}
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for {
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key, path = path[0], path[1:len(path)]
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value, ok := submap[key]
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if !ok {
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return "", nil
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}
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if len(path) > 0 {
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submap, ok = value.(map[string]interface{})
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if !ok {
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return "", fmt.Errorf("Expected an object, but was %#v", value)
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}
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} else {
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if value == nil {
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// Actual null element.
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return "", nil
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}
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url, ok := value.(string)
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if !ok {
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return "", fmt.Errorf("Expected a string, but was %#v", value)
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}
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return url, nil
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}
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}
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}
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// GetBody returns the linked page's body. This method is needed to satisfy the
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// Page interface.
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func (current LinkedPageBase) GetBody() interface{} {
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return current.Body
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}
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