88 lines
2.1 KiB
Go
88 lines
2.1 KiB
Go
package analytics
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import (
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"reflect"
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"strings"
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)
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// Imitate what what the JSON package would do when serializing a struct value,
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// the only difference is we we don't serialize zero-value struct fields as well.
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// Note that this function doesn't recursively convert structures to maps, only
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// the value passed as argument is transformed.
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func structToMap(v reflect.Value, m map[string]interface{}) map[string]interface{} {
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t := v.Type()
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n := t.NumField()
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if m == nil {
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m = make(map[string]interface{}, n)
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}
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for i := 0; i != n; i++ {
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field := t.Field(i)
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value := v.Field(i)
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name, omitempty := parseJsonTag(field.Tag.Get("json"), field.Name)
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if name != "-" && !(omitempty && isZeroValue(value)) {
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m[name] = value.Interface()
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}
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}
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return m
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}
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// Parses a JSON tag the way the json package would do it, returing the expected
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// name of the field once serialized and if empty values should be omitted.
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func parseJsonTag(tag string, defName string) (name string, omitempty bool) {
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args := strings.Split(tag, ",")
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if len(args) == 0 || len(args[0]) == 0 {
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name = defName
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} else {
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name = args[0]
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}
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if len(args) > 1 && args[1] == "omitempty" {
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omitempty = true
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}
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return
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}
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// Checks if the value given as argument is a zero-value, it is based on the
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// isEmptyValue function in https://golang.org/src/encoding/json/encode.go
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// but also checks struct types recursively.
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func isZeroValue(v reflect.Value) bool {
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switch v.Kind() {
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case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
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return v.Len() == 0
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case reflect.Bool:
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return !v.Bool()
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return v.Int() == 0
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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return v.Uint() == 0
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case reflect.Float32, reflect.Float64:
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return v.Float() == 0
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case reflect.Interface, reflect.Ptr:
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return v.IsNil()
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case reflect.Struct:
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for i, n := 0, v.NumField(); i != n; i++ {
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if !isZeroValue(v.Field(i)) {
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return false
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}
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}
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return true
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case reflect.Invalid:
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return true
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}
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return false
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}
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