'sort' template function used to accept only each element's struct field
name, method name and map key name as its second argument. This extends
it to accept a field/method/key chaining key string like
'Params.foo.bar' as the argument. It evaluates sub elements of each
array or map elements and sorts by them.
Typical use case would be sorting pages by user defined front matter
value. For example, sorting pages by 'Params.foo.bar' is possible by
writing the following template code
{{ range sort .Data.Pages "Params.foo.bar" }}
{{ .Content }}
{{ end }}
It ignores all leading and trailing dots so "Params.foo.bar" can be
written in ".Params.foo.bar"
This also fixes the issue that 'sort' cannot evaluate a pointer value.
Fix#1330
sort template function returns `[]interface{}` type slice value
regardless of its original element type.
This fixes it to keep the original element type. For example, if it
sorts `map[string]int` type value, it returns `[]int` slice value
instead of `[]interface{}` slice value.
`where` template function's internal condition check function always
returns `false` when a target value doesn't exist or it's nil value but
this behavior makes it difficult to filter values which doesn't have a
particular parameter.
To solve it, this adds nil value comparison to the function.
`where Values ".Param.key" nil` like clause can be used for the case
above.
Only "=", "==", "eq", "!=", "<>", "ne" operators are allowed to be used
with `nil`. If an other operator is passed with `nil`, the condition
check function returns `false` like before.
Fix#1232
Where `first` will return the first N items of a rangeable list,
`after` will return all items after the Nth item.
This allows the user to do something with the first N items and
something different with the remaining items after N.
`substr` template function takes one or two range arguments. Both
arguments must be int type values but if it is used with a calclation
function e.g. `add`, `len` etc, it causes a wrong type error.
This fixes the issue to allow the function to take other integer type
variant like `int64` etc.
This also includes a small fix on no range argument case.
Fix#1190
`where` tpl function doesn't support `time.Time` type so if people want
to compare such values, it's required that these values are converted
into `int` and compare them.
This improves it. If `time.Time` values are passed to `where`, it
converts them into `int` internally, compares them and returns the
result.
See also
http://discuss.gohugo.io/t/future-posts-and-past-posts/1229/3
