74 lines
1.7 KiB
Go
74 lines
1.7 KiB
Go
package multiconfig
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import (
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"fmt"
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"reflect"
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"github.com/fatih/structs"
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)
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// Validator validates the config against any predefined rules, those predefined
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// rules should be given to this package. The implementer will be responsible
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// for the logic.
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type Validator interface {
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// Validate validates the config struct
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Validate(s interface{}) error
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}
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// RequiredValidator validates the struct against zero values.
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type RequiredValidator struct {
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// TagName holds the validator tag name. The default is "required"
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TagName string
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// TagValue holds the expected value of the validator. The default is "true"
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TagValue string
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}
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// Validate validates the given struct agaist field's zero values. If
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// intentionaly, the value of a field is `zero-valued`(e.g false, 0, "")
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// required tag should not be set for that field.
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func (e *RequiredValidator) Validate(s interface{}) error {
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if e.TagName == "" {
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e.TagName = "required"
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}
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if e.TagValue == "" {
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e.TagValue = "true"
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}
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for _, field := range structs.Fields(s) {
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if err := e.processField("", field); err != nil {
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return err
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}
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}
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return nil
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}
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func (e *RequiredValidator) processField(fieldName string, field *structs.Field) error {
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fieldName += field.Name()
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switch field.Kind() {
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case reflect.Struct:
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// this is used for error messages below, when we have an error at the
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// child properties add parent properties into the error message as well
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fieldName += "."
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for _, f := range field.Fields() {
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if err := e.processField(fieldName, f); err != nil {
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return err
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}
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}
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default:
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val := field.Tag(e.TagName)
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if val != e.TagValue {
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return nil
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}
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if field.IsZero() {
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return fmt.Errorf("multiconfig: field '%s' is required", fieldName)
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}
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}
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return nil
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}
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