/* Package validator implements value validations for structs and individual fields based on tags. It can also handle Cross-Field and Cross-Struct validation for nested structs and has the ability to dive into arrays and maps of any type. see more examples https://github.com/go-playground/validator/tree/master/_examples Singleton Validator is designed to be thread-safe and used as a singleton instance. It caches information about your struct and validations, in essence only parsing your validation tags once per struct type. Using multiple instances neglects the benefit of caching. The not thread-safe functions are explicitly marked as such in the documentation. Validation Functions Return Type error Doing things this way is actually the way the standard library does, see the file.Open method here: https://golang.org/pkg/os/#Open. The authors return type "error" to avoid the issue discussed in the following, where err is always != nil: http://stackoverflow.com/a/29138676/3158232 https://github.com/go-playground/validator/issues/134 Validator only InvalidValidationError for bad validation input, nil or ValidationErrors as type error; so, in your code all you need to do is check if the error returned is not nil, and if it's not check if error is InvalidValidationError ( if necessary, most of the time it isn't ) type cast it to type ValidationErrors like so err.(validator.ValidationErrors). Custom Validation Functions Custom Validation functions can be added. Example: // Structure func customFunc(fl validator.FieldLevel) bool { if fl.Field().String() == "invalid" { return false } return true } validate.RegisterValidation("custom tag name", customFunc) // NOTES: using the same tag name as an existing function // will overwrite the existing one Cross-Field Validation Cross-Field Validation can be done via the following tags: - eqfield - nefield - gtfield - gtefield - ltfield - ltefield - eqcsfield - necsfield - gtcsfield - gtecsfield - ltcsfield - ltecsfield If, however, some custom cross-field validation is required, it can be done using a custom validation. Why not just have cross-fields validation tags (i.e. only eqcsfield and not eqfield)? The reason is efficiency. If you want to check a field within the same struct "eqfield" only has to find the field on the same struct (1 level). But, if we used "eqcsfield" it could be multiple levels down. Example: type Inner struct { StartDate time.Time } type Outer struct { InnerStructField *Inner CreatedAt time.Time `validate:"ltecsfield=InnerStructField.StartDate"` } now := time.Now() inner := &Inner{ StartDate: now, } outer := &Outer{ InnerStructField: inner, CreatedAt: now, } errs := validate.Struct(outer) // NOTE: when calling validate.Struct(val) topStruct will be the top level struct passed // into the function // when calling validate.VarWithValue(val, field, tag) val will be // whatever you pass, struct, field... // when calling validate.Field(field, tag) val will be nil Multiple Validators Multiple validators on a field will process in the order defined. Example: type Test struct { Field `validate:"max=10,min=1"` } // max will be checked then min Bad Validator definitions are not handled by the library. Example: type Test struct { Field `validate:"min=10,max=0"` } // this definition of min max will never succeed Using Validator Tags Baked In Cross-Field validation only compares fields on the same struct. If Cross-Field + Cross-Struct validation is needed you should implement your own custom validator. Comma (",") is the default separator of validation tags. If you wish to have a comma included within the parameter (i.e. excludesall=,) you will need to use the UTF-8 hex representation 0x2C, which is replaced in the code as a comma, so the above will become excludesall=0x2C. type Test struct { Field `validate:"excludesall=,"` // BAD! Do not include a comma. Field `validate:"excludesall=0x2C"` // GOOD! Use the UTF-8 hex representation. } Pipe ("|") is the 'or' validation tags deparator. If you wish to have a pipe included within the parameter i.e. excludesall=| you will need to use the UTF-8 hex representation 0x7C, which is replaced in the code as a pipe, so the above will become excludesall=0x7C type Test struct { Field `validate:"excludesall=|"` // BAD! Do not include a a pipe! Field `validate:"excludesall=0x7C"` // GOOD! Use the UTF-8 hex representation. } Baked In Validators and Tags Here is a list of the current built in validators: Skip Field Tells the validation to skip this struct field; this is particularly handy in ignoring embedded structs from being validated. (Usage: -) Usage: - Or Operator This is the 'or' operator allowing multiple validators to be used and accepted. (Usage: rgb|rgba) <-- this would allow either rgb or rgba colors to be accepted. This can also be combined with 'and' for example ( Usage: omitempty,rgb|rgba) Usage: | StructOnly When a field that is a nested struct is encountered, and contains this flag any validation on the nested struct will be run, but none of the nested struct fields will be validated. This is useful if inside of your program you know the struct will be valid, but need to verify it has been assigned. NOTE: only "required" and "omitempty" can be used on a struct itself. Usage: structonly NoStructLevel Same as structonly tag except that any struct level validations will not run. Usage: nostructlevel Omit Empty Allows conditional validation, for example if a field is not set with a value (Determined by the "required" validator) then other validation such as min or max won't run, but if a value is set validation will run. Usage: omitempty Dive This tells the validator to dive into a slice, array or map and validate that level of the slice, array or map with the validation tags that follow. Multidimensional nesting is also supported, each level you wish to dive will require another dive tag. dive has some sub-tags, 'keys' & 'endkeys', please see the Keys & EndKeys section just below. Usage: dive Example #1 [][]string with validation tag "gt=0,dive,len=1,dive,required" // gt=0 will be applied to [] // len=1 will be applied to []string // required will be applied to string Example #2 [][]string with validation tag "gt=0,dive,dive,required" // gt=0 will be applied to [] // []string will be spared validation // required will be applied to string Keys & EndKeys These are to be used together directly after the dive tag and tells the validator that anything between 'keys' and 'endkeys' applies to the keys of a map and not the values; think of it like the 'dive' tag, but for map keys instead of values. Multidimensional nesting is also supported, each level you wish to validate will require another 'keys' and 'endkeys' tag. These tags are only valid for maps. Usage: dive,keys,othertagvalidation(s),endkeys,valuevalidationtags Example #1 map[string]string with validation tag "gt=0,dive,keys,eg=1|eq=2,endkeys,required" // gt=0 will be applied to the map itself // eg=1|eq=2 will be applied to the map keys // required will be applied to map values Example #2 map[[2]string]string with validation tag "gt=0,dive,keys,dive,eq=1|eq=2,endkeys,required" // gt=0 will be applied to the map itself // eg=1|eq=2 will be applied to each array element in the the map keys // required will be applied to map values Required This validates that the value is not the data types default zero value. For numbers ensures value is not zero. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: required Required If The field under validation must be present and not empty only if all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: required_if Examples: // require the field if the Field1 is equal to the parameter given: Usage: required_if=Field1 foobar // require the field if the Field1 and Field2 is equal to the value respectively: Usage: required_if=Field1 foo Field2 bar Required Unless The field under validation must be present and not empty unless all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: required_unless Examples: // require the field unless the Field1 is equal to the parameter given: Usage: required_unless=Field1 foobar // require the field unless the Field1 and Field2 is equal to the value respectively: Usage: required_unless=Field1 foo Field2 bar Required With The field under validation must be present and not empty only if any of the other specified fields are present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: required_with Examples: // require the field if the Field1 is present: Usage: required_with=Field1 // require the field if the Field1 or Field2 is present: Usage: required_with=Field1 Field2 Required With All The field under validation must be present and not empty only if all of the other specified fields are present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: required_with_all Example: // require the field if the Field1 and Field2 is present: Usage: required_with_all=Field1 Field2 Required Without The field under validation must be present and not empty only when any of the other specified fields are not present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: required_without Examples: // require the field if the Field1 is not present: Usage: required_without=Field1 // require the field if the Field1 or Field2 is not present: Usage: required_without=Field1 Field2 Required Without All The field under validation must be present and not empty only when all of the other specified fields are not present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: required_without_all Example: // require the field if the Field1 and Field2 is not present: Usage: required_without_all=Field1 Field2 Excluded If The field under validation must not be present or not empty only if all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: excluded_if Examples: // exclude the field if the Field1 is equal to the parameter given: Usage: excluded_if=Field1 foobar // exclude the field if the Field1 and Field2 is equal to the value respectively: Usage: excluded_if=Field1 foo Field2 bar Excluded Unless The field under validation must not be present or empty unless all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Usage: excluded_unless Examples: // exclude the field unless the Field1 is equal to the parameter given: Usage: excluded_unless=Field1 foobar // exclude the field unless the Field1 and Field2 is equal to the value respectively: Usage: excluded_unless=Field1 foo Field2 bar Is Default This validates that the value is the default value and is almost the opposite of required. Usage: isdefault Length For numbers, length will ensure that the value is equal to the parameter given. For strings, it checks that the string length is exactly that number of characters. For slices, arrays, and maps, validates the number of items. Example #1 Usage: len=10 Example #2 (time.Duration) For time.Duration, len will ensure that the value is equal to the duration given in the parameter. Usage: len=1h30m Maximum For numbers, max will ensure that the value is less than or equal to the parameter given. For strings, it checks that the string length is at most that number of characters. For slices, arrays, and maps, validates the number of items. Example #1 Usage: max=10 Example #2 (time.Duration) For time.Duration, max will ensure that the value is less than or equal to the duration given in the parameter. Usage: max=1h30m Minimum For numbers, min will ensure that the value is greater or equal to the parameter given. For strings, it checks that the string length is at least that number of characters. For slices, arrays, and maps, validates the number of items. Example #1 Usage: min=10 Example #2 (time.Duration) For time.Duration, min will ensure that the value is greater than or equal to the duration given in the parameter. Usage: min=1h30m Equals For strings & numbers, eq will ensure that the value is equal to the parameter given. For slices, arrays, and maps, validates the number of items. Example #1 Usage: eq=10 Example #2 (time.Duration) For time.Duration, eq will ensure that the value is equal to the duration given in the parameter. Usage: eq=1h30m Not Equal For strings & numbers, ne will ensure that the value is not equal to the parameter given. For slices, arrays, and maps, validates the number of items. Example #1 Usage: ne=10 Example #2 (time.Duration) For time.Duration, ne will ensure that the value is not equal to the duration given in the parameter. Usage: ne=1h30m One Of For strings, ints, and uints, oneof will ensure that the value is one of the values in the parameter. The parameter should be a list of values separated by whitespace. Values may be strings or numbers. To match strings with spaces in them, include the target string between single quotes. Usage: oneof=red green oneof='red green' 'blue yellow' oneof=5 7 9 Greater Than For numbers, this will ensure that the value is greater than the parameter given. For strings, it checks that the string length is greater than that number of characters. For slices, arrays and maps it validates the number of items. Example #1 Usage: gt=10 Example #2 (time.Time) For time.Time ensures the time value is greater than time.Now.UTC(). Usage: gt Example #3 (time.Duration) For time.Duration, gt will ensure that the value is greater than the duration given in the parameter. Usage: gt=1h30m Greater Than or Equal Same as 'min' above. Kept both to make terminology with 'len' easier. Example #1 Usage: gte=10 Example #2 (time.Time) For time.Time ensures the time value is greater than or equal to time.Now.UTC(). Usage: gte Example #3 (time.Duration) For time.Duration, gte will ensure that the value is greater than or equal to the duration given in the parameter. Usage: gte=1h30m Less Than For numbers, this will ensure that the value is less than the parameter given. For strings, it checks that the string length is less than that number of characters. For slices, arrays, and maps it validates the number of items. Example #1 Usage: lt=10 Example #2 (time.Time) For time.Time ensures the time value is less than time.Now.UTC(). Usage: lt Example #3 (time.Duration) For time.Duration, lt will ensure that the value is less than the duration given in the parameter. Usage: lt=1h30m Less Than or Equal Same as 'max' above. Kept both to make terminology with 'len' easier. Example #1 Usage: lte=10 Example #2 (time.Time) For time.Time ensures the time value is less than or equal to time.Now.UTC(). Usage: lte Example #3 (time.Duration) For time.Duration, lte will ensure that the value is less than or equal to the duration given in the parameter. Usage: lte=1h30m Field Equals Another Field This will validate the field value against another fields value either within a struct or passed in field. Example #1: // Validation on Password field using: Usage: eqfield=ConfirmPassword Example #2: // Validating by field: validate.VarWithValue(password, confirmpassword, "eqfield") Field Equals Another Field (relative) This does the same as eqfield except that it validates the field provided relative to the top level struct. Usage: eqcsfield=InnerStructField.Field) Field Does Not Equal Another Field This will validate the field value against another fields value either within a struct or passed in field. Examples: // Confirm two colors are not the same: // // Validation on Color field: Usage: nefield=Color2 // Validating by field: validate.VarWithValue(color1, color2, "nefield") Field Does Not Equal Another Field (relative) This does the same as nefield except that it validates the field provided relative to the top level struct. Usage: necsfield=InnerStructField.Field Field Greater Than Another Field Only valid for Numbers, time.Duration and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: // Validation on End field using: validate.Struct Usage(gtfield=Start) Example #2: // Validating by field: validate.VarWithValue(start, end, "gtfield") Field Greater Than Another Relative Field This does the same as gtfield except that it validates the field provided relative to the top level struct. Usage: gtcsfield=InnerStructField.Field Field Greater Than or Equal To Another Field Only valid for Numbers, time.Duration and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: // Validation on End field using: validate.Struct Usage(gtefield=Start) Example #2: // Validating by field: validate.VarWithValue(start, end, "gtefield") Field Greater Than or Equal To Another Relative Field This does the same as gtefield except that it validates the field provided relative to the top level struct. Usage: gtecsfield=InnerStructField.Field Less Than Another Field Only valid for Numbers, time.Duration and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: // Validation on End field using: validate.Struct Usage(ltfield=Start) Example #2: // Validating by field: validate.VarWithValue(start, end, "ltfield") Less Than Another Relative Field This does the same as ltfield except that it validates the field provided relative to the top level struct. Usage: ltcsfield=InnerStructField.Field Less Than or Equal To Another Field Only valid for Numbers, time.Duration and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: // Validation on End field using: validate.Struct Usage(ltefield=Start) Example #2: // Validating by field: validate.VarWithValue(start, end, "ltefield") Less Than or Equal To Another Relative Field This does the same as ltefield except that it validates the field provided relative to the top level struct. Usage: ltecsfield=InnerStructField.Field Field Contains Another Field This does the same as contains except for struct fields. It should only be used with string types. See the behavior of reflect.Value.String() for behavior on other types. Usage: containsfield=InnerStructField.Field Field Excludes Another Field This does the same as excludes except for struct fields. It should only be used with string types. See the behavior of reflect.Value.String() for behavior on other types. Usage: excludesfield=InnerStructField.Field Unique For arrays & slices, unique will ensure that there are no duplicates. For maps, unique will ensure that there are no duplicate values. For slices of struct, unique will ensure that there are no duplicate values in a field of the struct specified via a parameter. // For arrays, slices, and maps: Usage: unique // For slices of struct: Usage: unique=field Alpha Only This validates that a string value contains ASCII alpha characters only Usage: alpha Alphanumeric This validates that a string value contains ASCII alphanumeric characters only Usage: alphanum Alpha Unicode This validates that a string value contains unicode alpha characters only Usage: alphaunicode Alphanumeric Unicode This validates that a string value contains unicode alphanumeric characters only Usage: alphanumunicode Boolean This validates that a string value can successfully be parsed into a boolean with strconv.ParseBool Usage: boolean Number This validates that a string value contains number values only. For integers or float it returns true. Usage: number Numeric This validates that a string value contains a basic numeric value. basic excludes exponents etc... for integers or float it returns true. Usage: numeric Hexadecimal String This validates that a string value contains a valid hexadecimal. Usage: hexadecimal Hexcolor String This validates that a string value contains a valid hex color including hashtag (#) Usage: hexcolor Lowercase String This validates that a string value contains only lowercase characters. An empty string is not a valid lowercase string. Usage: lowercase Uppercase String This validates that a string value contains only uppercase characters. An empty string is not a valid uppercase string. Usage: uppercase RGB String This validates that a string value contains a valid rgb color Usage: rgb RGBA String This validates that a string value contains a valid rgba color Usage: rgba HSL String This validates that a string value contains a valid hsl color Usage: hsl HSLA String This validates that a string value contains a valid hsla color Usage: hsla E.164 Phone Number String This validates that a string value contains a valid E.164 Phone number https://en.wikipedia.org/wiki/E.164 (ex. +1123456789) Usage: e164 E-mail String This validates that a string value contains a valid email This may not conform to all possibilities of any rfc standard, but neither does any email provider accept all possibilities. Usage: email JSON String This validates that a string value is valid JSON Usage: json JWT String This validates that a string value is a valid JWT Usage: jwt File path This validates that a string value contains a valid file path and that the file exists on the machine. This is done using os.Stat, which is a platform independent function. Usage: file URL String This validates that a string value contains a valid url This will accept any url the golang request uri accepts but must contain a schema for example http:// or rtmp:// Usage: url URI String This validates that a string value contains a valid uri This will accept any uri the golang request uri accepts Usage: uri Urn RFC 2141 String This validataes that a string value contains a valid URN according to the RFC 2141 spec. Usage: urn_rfc2141 Base64 String This validates that a string value contains a valid base64 value. Although an empty string is valid base64 this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag. Usage: base64 Base64URL String This validates that a string value contains a valid base64 URL safe value according the the RFC4648 spec. Although an empty string is a valid base64 URL safe value, this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag. Usage: base64url Bitcoin Address This validates that a string value contains a valid bitcoin address. The format of the string is checked to ensure it matches one of the three formats P2PKH, P2SH and performs checksum validation. Usage: btc_addr Bitcoin Bech32 Address (segwit) This validates that a string value contains a valid bitcoin Bech32 address as defined by bip-0173 (https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) Special thanks to Pieter Wuille for providng reference implementations. Usage: btc_addr_bech32 Ethereum Address This validates that a string value contains a valid ethereum address. The format of the string is checked to ensure it matches the standard Ethereum address format. Usage: eth_addr Contains This validates that a string value contains the substring value. Usage: contains=@ Contains Any This validates that a string value contains any Unicode code points in the substring value. Usage: containsany=!@#? Contains Rune This validates that a string value contains the supplied rune value. Usage: containsrune=@ Excludes This validates that a string value does not contain the substring value. Usage: excludes=@ Excludes All This validates that a string value does not contain any Unicode code points in the substring value. Usage: excludesall=!@#? Excludes Rune This validates that a string value does not contain the supplied rune value. Usage: excludesrune=@ Starts With This validates that a string value starts with the supplied string value Usage: startswith=hello Ends With This validates that a string value ends with the supplied string value Usage: endswith=goodbye Does Not Start With This validates that a string value does not start with the supplied string value Usage: startsnotwith=hello Does Not End With This validates that a string value does not end with the supplied string value Usage: endsnotwith=goodbye International Standard Book Number This validates that a string value contains a valid isbn10 or isbn13 value. Usage: isbn International Standard Book Number 10 This validates that a string value contains a valid isbn10 value. Usage: isbn10 International Standard Book Number 13 This validates that a string value contains a valid isbn13 value. Usage: isbn13 Universally Unique Identifier UUID This validates that a string value contains a valid UUID. Uppercase UUID values will not pass - use `uuid_rfc4122` instead. Usage: uuid Universally Unique Identifier UUID v3 This validates that a string value contains a valid version 3 UUID. Uppercase UUID values will not pass - use `uuid3_rfc4122` instead. Usage: uuid3 Universally Unique Identifier UUID v4 This validates that a string value contains a valid version 4 UUID. Uppercase UUID values will not pass - use `uuid4_rfc4122` instead. Usage: uuid4 Universally Unique Identifier UUID v5 This validates that a string value contains a valid version 5 UUID. Uppercase UUID values will not pass - use `uuid5_rfc4122` instead. Usage: uuid5 Universally Unique Lexicographically Sortable Identifier ULID This validates that a string value contains a valid ULID value. Usage: ulid ASCII This validates that a string value contains only ASCII characters. NOTE: if the string is blank, this validates as true. Usage: ascii Printable ASCII This validates that a string value contains only printable ASCII characters. NOTE: if the string is blank, this validates as true. Usage: printascii Multi-Byte Characters This validates that a string value contains one or more multibyte characters. NOTE: if the string is blank, this validates as true. Usage: multibyte Data URL This validates that a string value contains a valid DataURI. NOTE: this will also validate that the data portion is valid base64 Usage: datauri Latitude This validates that a string value contains a valid latitude. Usage: latitude Longitude This validates that a string value contains a valid longitude. Usage: longitude Social Security Number SSN This validates that a string value contains a valid U.S. Social Security Number. Usage: ssn Internet Protocol Address IP This validates that a string value contains a valid IP Address. Usage: ip Internet Protocol Address IPv4 This validates that a string value contains a valid v4 IP Address. Usage: ipv4 Internet Protocol Address IPv6 This validates that a string value contains a valid v6 IP Address. Usage: ipv6 Classless Inter-Domain Routing CIDR This validates that a string value contains a valid CIDR Address. Usage: cidr Classless Inter-Domain Routing CIDRv4 This validates that a string value contains a valid v4 CIDR Address. Usage: cidrv4 Classless Inter-Domain Routing CIDRv6 This validates that a string value contains a valid v6 CIDR Address. Usage: cidrv6 Transmission Control Protocol Address TCP This validates that a string value contains a valid resolvable TCP Address. Usage: tcp_addr Transmission Control Protocol Address TCPv4 This validates that a string value contains a valid resolvable v4 TCP Address. Usage: tcp4_addr Transmission Control Protocol Address TCPv6 This validates that a string value contains a valid resolvable v6 TCP Address. Usage: tcp6_addr User Datagram Protocol Address UDP This validates that a string value contains a valid resolvable UDP Address. Usage: udp_addr User Datagram Protocol Address UDPv4 This validates that a string value contains a valid resolvable v4 UDP Address. Usage: udp4_addr User Datagram Protocol Address UDPv6 This validates that a string value contains a valid resolvable v6 UDP Address. Usage: udp6_addr Internet Protocol Address IP This validates that a string value contains a valid resolvable IP Address. Usage: ip_addr Internet Protocol Address IPv4 This validates that a string value contains a valid resolvable v4 IP Address. Usage: ip4_addr Internet Protocol Address IPv6 This validates that a string value contains a valid resolvable v6 IP Address. Usage: ip6_addr Unix domain socket end point Address This validates that a string value contains a valid Unix Address. Usage: unix_addr Media Access Control Address MAC This validates that a string value contains a valid MAC Address. Usage: mac Note: See Go's ParseMAC for accepted formats and types: http://golang.org/src/net/mac.go?s=866:918#L29 Hostname RFC 952 This validates that a string value is a valid Hostname according to RFC 952 https://tools.ietf.org/html/rfc952 Usage: hostname Hostname RFC 1123 This validates that a string value is a valid Hostname according to RFC 1123 https://tools.ietf.org/html/rfc1123 Usage: hostname_rfc1123 or if you want to continue to use 'hostname' in your tags, create an alias. Full Qualified Domain Name (FQDN) This validates that a string value contains a valid FQDN. Usage: fqdn HTML Tags This validates that a string value appears to be an HTML element tag including those described at https://developer.mozilla.org/en-US/docs/Web/HTML/Element Usage: html HTML Encoded This validates that a string value is a proper character reference in decimal or hexadecimal format Usage: html_encoded URL Encoded This validates that a string value is percent-encoded (URL encoded) according to https://tools.ietf.org/html/rfc3986#section-2.1 Usage: url_encoded Directory This validates that a string value contains a valid directory and that it exists on the machine. This is done using os.Stat, which is a platform independent function. Usage: dir HostPort This validates that a string value contains a valid DNS hostname and port that can be used to valiate fields typically passed to sockets and connections. Usage: hostname_port Datetime This validates that a string value is a valid datetime based on the supplied datetime format. Supplied format must match the official Go time format layout as documented in https://golang.org/pkg/time/ Usage: datetime=2006-01-02 Iso3166-1 alpha-2 This validates that a string value is a valid country code based on iso3166-1 alpha-2 standard. see: https://www.iso.org/iso-3166-country-codes.html Usage: iso3166_1_alpha2 Iso3166-1 alpha-3 This validates that a string value is a valid country code based on iso3166-1 alpha-3 standard. see: https://www.iso.org/iso-3166-country-codes.html Usage: iso3166_1_alpha3 Iso3166-1 alpha-numeric This validates that a string value is a valid country code based on iso3166-1 alpha-numeric standard. see: https://www.iso.org/iso-3166-country-codes.html Usage: iso3166_1_alpha3 BCP 47 Language Tag This validates that a string value is a valid BCP 47 language tag, as parsed by language.Parse. More information on https://pkg.go.dev/golang.org/x/text/language Usage: bcp47_language_tag BIC (SWIFT code) This validates that a string value is a valid Business Identifier Code (SWIFT code), defined in ISO 9362. More information on https://www.iso.org/standard/60390.html Usage: bic RFC 1035 label This validates that a string value is a valid dns RFC 1035 label, defined in RFC 1035. More information on https://datatracker.ietf.org/doc/html/rfc1035 Usage: dns_rfc1035_label TimeZone This validates that a string value is a valid time zone based on the time zone database present on the system. Although empty value and Local value are allowed by time.LoadLocation golang function, they are not allowed by this validator. More information on https://golang.org/pkg/time/#LoadLocation Usage: timezone Semantic Version This validates that a string value is a valid semver version, defined in Semantic Versioning 2.0.0. More information on https://semver.org/ Usage: semver Credit Card This validates that a string value contains a valid credit card number using Luhn algoritm. Usage: credit_card Alias Validators and Tags NOTE: When returning an error, the tag returned in "FieldError" will be the alias tag unless the dive tag is part of the alias. Everything after the dive tag is not reported as the alias tag. Also, the "ActualTag" in the before case will be the actual tag within the alias that failed. Here is a list of the current built in alias tags: "iscolor" alias is "hexcolor|rgb|rgba|hsl|hsla" (Usage: iscolor) "country_code" alias is "iso3166_1_alpha2|iso3166_1_alpha3|iso3166_1_alpha_numeric" (Usage: country_code) Validator notes: regex a regex validator won't be added because commas and = signs can be part of a regex which conflict with the validation definitions. Although workarounds can be made, they take away from using pure regex's. Furthermore it's quick and dirty but the regex's become harder to maintain and are not reusable, so it's as much a programming philosophy as anything. In place of this new validator functions should be created; a regex can be used within the validator function and even be precompiled for better efficiency within regexes.go. And the best reason, you can submit a pull request and we can keep on adding to the validation library of this package! Non standard validators A collection of validation rules that are frequently needed but are more complex than the ones found in the baked in validators. A non standard validator must be registered manually like you would with your own custom validation functions. Example of registration and use: type Test struct { TestField string `validate:"yourtag"` } t := &Test{ TestField: "Test" } validate := validator.New() validate.RegisterValidation("yourtag", validators.NotBlank) Here is a list of the current non standard validators: NotBlank This validates that the value is not blank or with length zero. For strings ensures they do not contain only spaces. For channels, maps, slices and arrays ensures they don't have zero length. For others, a non empty value is required. Usage: notblank Panics This package panics when bad input is provided, this is by design, bad code like that should not make it to production. type Test struct { TestField string `validate:"nonexistantfunction=1"` } t := &Test{ TestField: "Test" } validate.Struct(t) // this will panic */ package validator