blob: d54e5027c799c5ea3fc84ef987acb970b1a3e6d0 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
# Generators {#sec-generators}
Generators are functions that create file formats from nix data structures, e. g. for configuration files. There are generators available for: `INI`, `JSON` and `YAML`
All generators follow a similar call interface: `generatorName configFunctions data`, where `configFunctions` is an attrset of user-defined functions that format nested parts of the content. They each have common defaults, so often they do not need to be set manually. An example is `mkSectionName ? (name: libStr.escape [ "[" "]" ] name)` from the `INI` generator. It receives the name of a section and sanitizes it. The default `mkSectionName` escapes `[` and `]` with a backslash.
Generators can be fine-tuned to produce exactly the file format required by your application/service. One example is an INI-file format which uses `: ` as separator, the strings `"yes"`/`"no"` as boolean values and requires all string values to be quoted:
```nix
with lib;
let
customToINI = generators.toINI {
# specifies how to format a key/value pair
mkKeyValue = generators.mkKeyValueDefault {
# specifies the generated string for a subset of nix values
mkValueString = v:
if v == true then ''"yes"''
else if v == false then ''"no"''
else if isString v then ''"${v}"''
# and delegats all other values to the default generator
else generators.mkValueStringDefault {} v;
} ":";
};
# the INI file can now be given as plain old nix values
in customToINI {
main = {
pushinfo = true;
autopush = false;
host = "localhost";
port = 42;
};
mergetool = {
merge = "diff3";
};
}
```
This will produce the following INI file as nix string:
```INI
[main]
autopush:"no"
host:"localhost"
port:42
pushinfo:"yes"
str\:ange:"very::strange"
[mergetool]
merge:"diff3"
```
::: {.note}
Nix store paths can be converted to strings by enclosing a derivation attribute like so: `"${drv}"`.
:::
Detailed documentation for each generator can be found in `lib/generators.nix`.
|