safing-portbase/database/query/README.md

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# Query
## Control Flow
- Grouping with `(` and `)`
- Chaining with `and` and `or`
- _NO_ mixing! Be explicit and use grouping.
- Negation with `not`
- in front of expression for group: `not (...)`
- inside expression for clause: `name not matches "^King "`
## Selectors
Supported by all feeders:
- root level field: `field`
- sub level field: `field.sub`
- array/slice/map access: `map.0`
- array/slice/map length: `map.#`
Please note that some feeders may have other special characters. It is advised to only use alphanumeric characters for keys.
## Operators
| Name | Textual | Req. Type | Internal Type | Compared with |
|-------------------------|--------------------|-----------|---------------|---------------------------|
| Equals | `==` | int | int64 | `==` |
| GreaterThan | `>` | int | int64 | `>` |
| GreaterThanOrEqual | `>=` | int | int64 | `>=` |
| LessThan | `<` | int | int64 | `<` |
| LessThanOrEqual | `<=` | int | int64 | `<=` |
| FloatEquals | `f==` | float | float64 | `==` |
| FloatGreaterThan | `f>` | float | float64 | `>` |
| FloatGreaterThanOrEqual | `f>=` | float | float64 | `>=` |
| FloatLessThan | `f<` | float | float64 | `<` |
| FloatLessThanOrEqual | `f<=` | float | float64 | `<=` |
| SameAs | `sameas`, `s==` | string | string | `==` |
| Contains | `contains`, `co` | string | string | `strings.Contains()` |
| StartsWith | `startswith`, `sw` | string | string | `strings.HasPrefix()` |
| EndsWith | `endswith`, `ew` | string | string | `strings.HasSuffix()` |
| In | `in` | string | string | for loop with `==` |
| Matches | `matches`, `re` | string | string | `regexp.Regexp.Matches()` |
| Is | `is` | bool* | bool | `==` |
| Exists | `exists`, `ex` | any | n/a | n/a |
\*accepts strings: 1, t, T, true, True, TRUE, 0, f, F, false, False, FALSE
## Escaping
If you need to use a control character within a value (ie. not for controlling), escape it with `\`.
It is recommended to wrap a word into parenthesis instead of escaping control characters, when possible.
| Location | Characters to be escaped |
|---|---|
| Within parenthesis (`"`) | `"`, `\` |
| Everywhere else | `(`, `)`, `"`, `\`, `\t`, `\r`, `\n`, ` ` (space) |