trim |
The `trim` function removes space from either side of a string:
```
trim " hello "
```
The above produces `hello`
|
trimAll |
Remove given characters from the front or back of a string:
```
trimAll "$" "$5.00"
```
The above returns `5.00` (as a string).
|
trimSuffix |
Trim just the suffix from a string:
```
trimSuffix "-" "hello-"
```
The above returns `hello`
|
trimPrefix |
Trim just the prefix from a string:
```
trimPrefix "-" "-hello"
```
The above returns `hello`
|
upper |
Convert the entire string to uppercase:
```
upper "hello"
```
The above returns `HELLO`
|
lower |
Convert the entire string to lowercase:
```
lower "HELLO"
```
The above returns `hello`
|
title |
Convert to title case:
```
title "hello world"
```
The above returns `Hello World`
|
repeat |
Repeat a string multiple times:
```
repeat 3 "hello"
```
The above returns `hellohellohello`
|
substr |
Get a substring from a string. It takes three parameters:
- start (int)
- end (int)
- string (string)
```
substr 0 5 "hello world"
```
The above returns `hello`
|
trunc |
Truncate a string (and add no suffix)
```
trunc 5 "hello world"
```
The above produces `hello`.
```
trunc -5 "hello world"
```
The above produces `world`.
|
contains |
Test to see if one string is contained inside of another:
```
contains "cat" "catch"
```
The above returns `true` because `catch` contains `cat`.
|
hasPrefix and hasSuffix |
The `hasPrefix` and `hasSuffix` functions test whether a string has a given
prefix or suffix:
```
hasPrefix "cat" "catch"
```
The above returns `true` because `catch` has the prefix `cat`.
|
quote and squote |
These functions wrap a string in double quotes (`quote`) or single quotes
(`squote`).
|
cat |
The `cat` function concatenates multiple strings together into one, separating
them with spaces:
```
cat "hello" "beautiful" "world"
```
The above produces `hello beautiful world`
|
indent |
The `indent` function indents every line in a given string to the specified
indent width. This is useful when aligning multi-line strings:
```
indent 4 $lots_of_text
```
The above will indent every line of text by 4 space characters.
|
nindent |
The `nindent` function is the same as the indent function, but prepends a new
line to the beginning of the string.
```
nindent 4 $lots_of_text
```
The above will indent every line of text by 4 space characters and add a new
line to the beginning.
|
replace |
Perform simple string replacement.
It takes three arguments:
- string to replace
- string to replace with
- source string
```
"I Am Henry VIII" | replace " " "-"
```
The above will produce `I-Am-Henry-VIII`
|
plural |
Pluralize a string.
```
len $fish | plural "one anchovy" "many anchovies"
```
In the above, if the length of the string is 1, the first argument will be
printed (`one anchovy`). Otherwise, the second argument will be printed
(`many anchovies`).
The arguments are:
- singular string
- plural string
- length integer
NOTE: Sprig does not currently support languages with more complex pluralization
rules. And `0` is considered a plural because the English language treats it
as such (`zero anchovies`). The Sprig developers are working on a solution for
better internationalization.
|
regexMatch, mustRegexMatch |
Returns true if the input string contains any match of the regular expression.
```
regexMatch "^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$" "test@acme.com"
```
The above produces `true`
`regexMatch` panics if there is a problem and `mustRegexMatch` returns an error to the
template engine if there is a problem.
|
regexFindAll, mustRegexFindAll |
Returns a slice of all matches of the regular expression in the input string.
The last parameter n determines the number of substrings to return, where -1 means return all matches
```
regexFindAll "[2,4,6,8]" "123456789" -1
```
The above produces `[2 4 6 8]`
`regexFindAll` panics if there is a problem and `mustRegexFindAll` returns an error to the
template engine if there is a problem.
|
regexFind, mustRegexFind |
Return the first (left most) match of the regular expression in the input string
```
regexFind "[a-zA-Z][1-9]" "abcd1234"
```
The above produces `d1`
`regexFind` panics if there is a problem and `mustRegexFind` returns an error to the
template engine if there is a problem.
|
regexReplaceAll, mustRegexReplaceAll |
Returns a copy of the input string, replacing matches of the Regexp with the replacement string replacement.
Inside string replacement, $ signs are interpreted as in Expand, so for instance $1 represents the text of the first submatch
```
regexReplaceAll "a(x*)b" "-ab-axxb-" "${1}W"
```
The above produces `-W-xxW-`
`regexReplaceAll` panics if there is a problem and `mustRegexReplaceAll` returns an error to the
template engine if there is a problem.
|
regexReplaceAllLiteral, mustRegexReplaceAllLiteral |
Returns a copy of the input string, replacing matches of the Regexp with the replacement string replacement
The replacement string is substituted directly, without using Expand
```
regexReplaceAllLiteral "a(x*)b" "-ab-axxb-" "${1}"
```
The above produces `-${1}-${1}-`
`regexReplaceAllLiteral` panics if there is a problem and `mustRegexReplaceAllLiteral` returns an error to the
template engine if there is a problem.
|
regexSplit, mustRegexSplit |
Slices the input string into substrings separated by the expression and returns a slice of the substrings between those expression matches. The last parameter `n` determines the number of substrings to return, where `-1` means return all matches
```
regexSplit "z+" "pizza" -1
```
The above produces `[pi a]`
`regexSplit` panics if there is a problem and `mustRegexSplit` returns an error to the
template engine if there is a problem.
|
regexQuoteMeta |
Returns a string that escapes all regular expression metacharacters inside the argument text;
the returned string is a regular expression matching the literal text.
```
regexQuoteMeta "1.2.3"
```
The above produces `1\.2\.3`
|
The [Conversion Functions](conversion.md) contain functions for converting strings. The [String List Functions](string_slice.md) contains
functions for working with an array of strings.
## String List Functions
These function operate on or generate slices of strings. In Go, a slice is a
growable array. In Sprig, it's a special case of a `list`.
add |
Sum numbers with `add`. Accepts two or more inputs.
```
add 1 2 3
```
|
add1 |
To increment by 1, use `add1`
|
sub |
To subtract, use `sub`
|
div |
Perform integer division with `div`
|
mod |
Modulo with `mod`
|
mul |
Multiply with `mul`. Accepts two or more inputs.
```
mul 1 2 3
```
|
max |
Return the largest of a series of integers:
This will return `3`:
```
max 1 2 3
```
|
min |
Return the smallest of a series of integers.
`min 1 2 3` will return `1`
|
floor |
Returns the greatest float value less than or equal to input value
`floor 123.9999` will return `123.0`
|
ceil |
Returns the greatest float value greater than or equal to input value
`ceil 123.001` will return `124.0`
|
round |
Returns a float value with the remainder rounded to the given number to digits after the decimal point.
`round 123.555555 3` will return `123.556`
|
randInt |
Returns a random integer value from min (inclusive) to max (exclusive).
```
randInt 12 30
```
The above will produce a random number in the range [12,30].
|
## Integer List Functions
now |
The current date/time. Use this in conjunction with other date functions.
|
ago |
The `ago` function returns duration from time.Now in seconds resolution.
```
ago .CreatedAt
```
returns in `time.Duration` String() format
```
2h34m7s
```
|
date |
The `date` function formats a date.
Format the date to YEAR-MONTH-DAY:
```
now | date "2006-01-02"
```
Date formatting in Go is a [little bit different](https://pauladamsmith.com/blog/2011/05/go_time.html).
In short, take this as the base date:
```
Mon Jan 2 15:04:05 MST 2006
```
Write it in the format you want. Above, `2006-01-02` is the same date, but
in the format we want.
|
dateInZone |
Same as `date`, but with a timezone.
```
dateInZone "2006-01-02" (now) "UTC"
```
|
duration |
Formats a given amount of seconds as a `time.Duration`.
This returns 1m35s
```
duration "95"
```
|
durationRound |
Rounds a given duration to the most significant unit. Strings and `time.Duration`
gets parsed as a duration, while a `time.Time` is calculated as the duration since.
This return 2h
```
durationRound "2h10m5s"
```
This returns 3mo
```
durationRound "2400h10m5s"
```
|
unixEpoch |
Returns the seconds since the unix epoch for a `time.Time`.
```
now | unixEpoch
```
|
dateModify, mustDateModify |
The `dateModify` takes a modification and a date and returns the timestamp.
Subtract an hour and thirty minutes from the current time:
```
now | date_modify "-1.5h"
```
If the modification format is wrong `dateModify` will return the date unmodified. `mustDateModify` will return an error otherwise.
|
htmlDate |
The `htmlDate` function formats a date for inserting into an HTML date picker
input field.
```
now | htmlDate
```
|
htmlDateInZone |
Same as htmlDate, but with a timezone.
```
htmlDateInZone (now) "UTC"
```
|
toDate, mustToDate |
`toDate` converts a string to a date. The first argument is the date layout and
the second the date string. If the string can't be convert it returns the zero
value.
`mustToDate` will return an error in case the string cannot be converted.
This is useful when you want to convert a string date to another format
(using pipe). The example below converts "2017-12-31" to "31/12/2017".
```
toDate "2006-01-02" "2017-12-31" | date "02/01/2006"
```
|
## Default Functions
Sprig provides tools for setting default values for templates.
default |
To set a simple default value, use `default`:
```
default "foo" .Bar
```
In the above, if `.Bar` evaluates to a non-empty value, it will be used. But if
it is empty, `foo` will be returned instead.
The definition of "empty" depends on type:
- Numeric: 0
- String: ""
- Lists: `[]`
- Dicts: `{}`
- Boolean: `false`
- And always `nil` (aka null)
For structs, there is no definition of empty, so a struct will never return the
default.
|
empty |
The `empty` function returns `true` if the given value is considered empty, and
`false` otherwise. The empty values are listed in the `default` section.
```
empty .Foo
```
Note that in Go template conditionals, emptiness is calculated for you. Thus,
you rarely need `if empty .Foo`. Instead, just use `if .Foo`.
|
coalesce |
The `coalesce` function takes a list of values and returns the first non-empty
one.
```
coalesce 0 1 2
```
The above returns `1`.
This function is useful for scanning through multiple variables or values:
```
coalesce .name .parent.name "Matt"
```
The above will first check to see if `.name` is empty. If it is not, it will return
that value. If it _is_ empty, `coalesce` will evaluate `.parent.name` for emptiness.
Finally, if both `.name` and `.parent.name` are empty, it will return `Matt`.
|
all |
The `all` function takes a list of values and returns true if all values are non-empty.
```
all 0 1 2
```
The above returns `false`.
This function is useful for evaluating multiple conditions of variables or values:
```
all (eq .Request.TLS.Version 0x0304) (.Request.ProtoAtLeast 2 0) (eq .Request.Method "POST")
```
The above will check http.Request is POST with tls 1.3 and http/2.
|
any |
The `any` function takes a list of values and returns true if any value is non-empty.
```
any 0 1 2
```
The above returns `true`.
This function is useful for evaluating multiple conditions of variables or values:
```
any (eq .Request.Method "GET") (eq .Request.Method "POST") (eq .Request.Method "OPTIONS")
```
The above will check http.Request method is one of GET/POST/OPTIONS.
|
fromJSON, mustFromJSON |
`fromJSON` decodes a JSON document into a structure. If the input cannot be decoded as JSON the function will return an empty string.
`mustFromJSON` will return an error in case the JSON is invalid.
```
fromJSON "{\"foo\": 55}"
```
|
toJSON, mustToJSON |
The `toJSON` function encodes an item into a JSON string. If the item cannot be converted to JSON the function will return an empty string.
`mustToJSON` will return an error in case the item cannot be encoded in JSON.
```
toJSON .Item
```
The above returns JSON string representation of `.Item`.
|
toPrettyJSON, mustToPrettyJSON |
The `toPrettyJSON` function encodes an item into a pretty (indented) JSON string.
```
toPrettyJSON .Item
```
The above returns indented JSON string representation of `.Item`.
|
toRawJSON, mustToRawJSON |
The `toRawJSON` function encodes an item into JSON string with HTML characters unescaped.
```
toRawJSON .Item
```
The above returns unescaped JSON string representation of `.Item`.
|
ternary |
The `ternary` function takes two values, and a test value. If the test value is
true, the first value will be returned. If the test value is empty, the second
value will be returned. This is similar to the c ternary operator.
### true test value
```
ternary "foo" "bar" true
```
or
```
true | ternary "foo" "bar"
```
The above returns `"foo"`.
### false test value
```
ternary "foo" "bar" false
```
or
```
false | ternary "foo" "bar"
```
The above returns `"bar"`.
|
## Encoding Functions
Sprig has the following encoding and decoding functions:
first, mustFirst |
To get the head item on a list, use `first`.
`first $myList` returns `1`
`first` panics if there is a problem while `mustFirst` returns an error to the
template engine if there is a problem.
|
rest, mustRest |
To get the tail of the list (everything but the first item), use `rest`.
`rest $myList` returns `[2 3 4 5]`
`rest` panics if there is a problem while `mustRest` returns an error to the
template engine if there is a problem.
|
last, mustLast |
To get the last item on a list, use `last`:
`last $myList` returns `5`. This is roughly analogous to reversing a list and
then calling `first`.
`last` panics if there is a problem while `mustLast` returns an error to the
template engine if there is a problem.
|
initial, mustInitial |
This compliments `last` by returning all _but_ the last element.
`initial $myList` returns `[1 2 3 4]`.
`initial` panics if there is a problem while `mustInitial` returns an error to the
template engine if there is a problem.
|
append, mustAppend |
Append a new item to an existing list, creating a new list.
```
$new = append $myList 6
```
The above would set `$new` to `[1 2 3 4 5 6]`. `$myList` would remain unaltered.
`append` panics if there is a problem while `mustAppend` returns an error to the
template engine if there is a problem.
|
prepend, mustPrepend |
Push an element onto the front of a list, creating a new list.
```
prepend $myList 0
```
The above would produce `[0 1 2 3 4 5]`. `$myList` would remain unaltered.
`prepend` panics if there is a problem while `mustPrepend` returns an error to the
template engine if there is a problem.
|
concat |
Concatenate arbitrary number of lists into one.
```
concat $myList ( list 6 7 ) ( list 8 )
```
The above would produce `[1 2 3 4 5 6 7 8]`. `$myList` would remain unaltered.
|
reverse, mustReverse |
Produce a new list with the reversed elements of the given list.
```
reverse $myList
```
The above would generate the list `[5 4 3 2 1]`.
`reverse` panics if there is a problem while `mustReverse` returns an error to the
template engine if there is a problem.
|
uniq, mustUniq |
Generate a list with all of the duplicates removed.
```
list 1 1 1 2 | uniq
```
The above would produce `[1 2]`
`uniq` panics if there is a problem while `mustUniq` returns an error to the
template engine if there is a problem.
|
without, mustWithout |
The `without` function filters items out of a list.
```
without $myList 3
```
The above would produce `[1 2 4 5]`
Without can take more than one filter:
```
without $myList 1 3 5
```
That would produce `[2 4]`
`without` panics if there is a problem while `mustWithout` returns an error to the
template engine if there is a problem.
|
has, mustHas |
Test to see if a list has a particular element.
```
has 4 $myList
```
The above would return `true`, while `has "hello" $myList` would return false.
`has` panics if there is a problem while `mustHas` returns an error to the
template engine if there is a problem.
|
compact, mustCompact |
Accepts a list and removes entries with empty values.
```
$list := list 1 "a" "foo" ""
$copy := compact $list
```
`compact` will return a new list with the empty (i.e., "") item removed.
`compact` panics if there is a problem and `mustCompact` returns an error to the
template engine if there is a problem.
|
slice, mustSlice |
To get partial elements of a list, use `slice list [n] [m]`. It is
equivalent of `list[n:m]`.
- `slice $myList` returns `[1 2 3 4 5]`. It is same as `myList[:]`.
- `slice $myList 3` returns `[4 5]`. It is same as `myList[3:]`.
- `slice $myList 1 3` returns `[2 3]`. It is same as `myList[1:3]`.
- `slice $myList 0 3` returns `[1 2 3]`. It is same as `myList[:3]`.
`slice` panics if there is a problem while `mustSlice` returns an error to the
template engine if there is a problem.
|
chunk |
To split a list into chunks of given size, use `chunk size list`. This is useful for pagination.
```
chunk 3 (list 1 2 3 4 5 6 7 8)
```
This produces list of lists `[ [ 1 2 3 ] [ 4 5 6 ] [ 7 8 ] ]`.
|
### A Note on List Internals
A list is implemented in Go as a `[]interface{}`. For Go developers embedding
Sprig, you may pass `[]interface{}` items into your template context and be
able to use all of the `list` functions on those items.
## Dictionaries and Dict Functions
Sprig provides a key/value storage type called a `dict` (short for "dictionary",
as in Python). A `dict` is an _unorder_ type.
The key to a dictionary **must be a string**. However, the value can be any
type, even another `dict` or `list`.
Unlike `list`s, `dict`s are not immutable. The `set` and `unset` functions will
modify the contents of a dictionary.
dict |
Creating dictionaries is done by calling the `dict` function and passing it a
list of pairs.
The following creates a dictionary with three items:
```
$myDict := dict "name1" "value1" "name2" "value2" "name3" "value 3"
```
|
get |
Given a map and a key, get the value from the map.
```
get $myDict "name1"
```
The above returns `"value1"`
Note that if the key is not found, this operation will simply return `""`. No error
will be generated.
|
set |
Use `set` to add a new key/value pair to a dictionary.
```
$_ := set $myDict "name4" "value4"
```
Note that `set` _returns the dictionary_ (a requirement of Go template functions),
so you may need to trap the value as done above with the `$_` assignment.
|
unset |
Given a map and a key, delete the key from the map.
```
$_ := unset $myDict "name4"
```
As with `set`, this returns the dictionary.
Note that if the key is not found, this operation will simply return. No error
will be generated.
|
hasKey |
The `hasKey` function returns `true` if the given dict contains the given key.
```
hasKey $myDict "name1"
```
If the key is not found, this returns `false`.
|
pluck |
The `pluck` function makes it possible to give one key and multiple maps, and
get a list of all of the matches:
```
pluck "name1" $myDict $myOtherDict
```
The above will return a `list` containing every found value (`[value1 otherValue1]`).
If the give key is _not found_ in a map, that map will not have an item in the
list (and the length of the returned list will be less than the number of dicts
in the call to `pluck`.
If the key is _found_ but the value is an empty value, that value will be
inserted.
A common idiom in Sprig templates is to uses `pluck... | first` to get the first
matching key out of a collection of dictionaries.
|
dig |
The `dig` function traverses a nested set of dicts, selecting keys from a list
of values. It returns a default value if any of the keys are not found at the
associated dict.
```
dig "user" "role" "humanName" "guest" $dict
```
Given a dict structured like
```
{
user: {
role: {
humanName: "curator"
}
}
}
```
the above would return `"curator"`. If the dict lacked even a `user` field,
the result would be `"guest"`.
Dig can be very useful in cases where you'd like to avoid guard clauses,
especially since Go's template package's `and` doesn't shortcut. For instance
`and a.maybeNil a.maybeNil.iNeedThis` will always evaluate
`a.maybeNil.iNeedThis`, and panic if `a` lacks a `maybeNil` field.)
`dig` accepts its dict argument last in order to support pipelining.
|
keys |
The `keys` function will return a `list` of all of the keys in one or more `dict`
types. Since a dictionary is _unordered_, the keys will not be in a predictable order.
They can be sorted with `sortAlpha`.
```
keys $myDict | sortAlpha
```
When supplying multiple dictionaries, the keys will be concatenated. Use the `uniq`
function along with `sortAlpha` to get a unqiue, sorted list of keys.
```
keys $myDict $myOtherDict | uniq | sortAlpha
```
|
pick |
The `pick` function selects just the given keys out of a dictionary, creating a
new `dict`.
```
$new := pick $myDict "name1" "name2"
```
The above returns `{name1: value1, name2: value2}`
|
omit |
The `omit` function is similar to `pick`, except it returns a new `dict` with all
the keys that _do not_ match the given keys.
```
$new := omit $myDict "name1" "name3"
```
The above returns `{name2: value2}`
|
values |
The `values` function is similar to `keys`, except it returns a new `list` with
all the values of the source `dict` (only one dictionary is supported).
```
$vals := values $myDict
```
The above returns `list["value1", "value2", "value 3"]`. Note that the `values`
function gives no guarantees about the result ordering- if you care about this,
then use `sortAlpha`.
|
## Type Conversion Functions
The following type conversion functions are provided by Sprig: