Find keys in object hierarchies using wildcard and glob matching and callbacks.
Install with npm:
$ npm install --save object-scan
const objectScan = require('object-scan');
objectScan(['a.*.f'])({ a: { b: { c: 'd' }, e: { f: 'g' } } });
// => [ 'a.e.f' ]
- Object and Array matching with e.g.
key.path
and[1]
- Wildcard matching with
*
and[*]
- Partial Wildcard matching with e.g.
mark*
,m?rk
,[*1]
or[?1]
- Arbitrary depth matching with
**
- Or-clause with e.g.
{a,b}
and[{0,1}]
- Exclusion with e.g.
!key
- Full support for escaping
- Input traversed exactly once during search
- Results returned in "delete-safe" order
- Search syntax is checked for correctness
- Dependency free, small in size and very performant
- Lots of tests to ensure correctness
Signature for all functions is
Fn(key, value, { parents, isMatch, matchedBy, excludedBy, traversedBy })
where:
key
is the key that the function is called for (respectsjoined
option).value
is the value for that key.parents
is array of form[parent, grandparent, ...]
.isMatch
is true if the last targeting needle exists and is non-excluding.matchedBy
are all non-excluding needles targeting the key.excludedBy
are all excluding needles targeting the key.traversedBy
are all needles involved in traversing the key.
Type: function
Default: undefined
If function is defined, it is called for every match. If false
is returned, the current key is excluded from the result.
Can be used as a callback function to do processing as matching keys are traversed.
Called in same order as matches would appear in result.
This method is conceptually similar to the callback function in Array.filter().
Type: function
Default: undefined
If function is defined, it is called for every key that is traversed by
the search. If true
is returned, all keys nested under the current key are
skipped in the search and from the final result.
Note that breakFn
is called before the corresponding filterFn
might be called.
Type: boolean
Default: false
Keys are returned as a string when set to true
instead of as a list.
Setting this option to true
will negatively impact performance.
Note that _.get and _.set fully support lists.
Type: boolean
Default: true
When set to false
, no array selectors should be used in any needles and arrays are automatically traversed.
Note that the results still include the array selectors.
Type: boolean
Default: true
When set to false
, no errors are thrown when:
- the input contains redundant needles
More extensive examples can be found in the tests.
const objectScan = require('object-scan');
const obj = {
a: {
b: {
c: 'd'
},
e: {
f: 'g'
},
h: ['i', 'j']
},
k: 'l'
};
// top level keys
objectScan(['*'], { joined: true })(obj);
// => ["k", "a"]
// nested keys
objectScan(['a.*.f'], { joined: true })(obj);
// => ["a.e.f"]
objectScan(['*.*.*'], { joined: true })(obj);
// => ["a.e.f", "a.b.c"]
// or filter
objectScan(['a.*.{c,f}'], { joined: true })(obj);
// => ["a.e.f", "a.b.c"]
objectScan(['a.*.{c,f}'])(obj);
// => [["a", "e", "f"], ["a", "b", "c"]]
// list filter
objectScan(['*.*[*]'], { joined: true })(obj);
// => ["a.h[1]", "a.h[0]"]
objectScan(['*[*]'], { joined: true })(obj);
// => []
// deep star filter
objectScan(['**'], { joined: true })(obj);
// => ["k", "a.h[1]", "a.h[0]", "a.h", "a.e.f", "a.e", "a.b.c", "a.b", "a"]
objectScan(['**.f'], { joined: true })(obj);
// => ["a.e.f"]
objectScan(['**[*]'], { joined: true })(obj);
// => ["a.h[1]", "a.h[0]"]
// exclusion filter
objectScan(['a.*,!a.e'], { joined: true })(obj);
// => ["a.h", "a.b"]
// value function
objectScan(['**'], { filterFn: (key, value) => typeof value === 'string', joined: true })(obj);
// => ["k", "a.h[1]", "a.h[0]", "a.e.f", "a.b.c"]
objectScan(['**'], { breakFn: (key) => key === 'a.b', joined: true })(obj);
// => ["k", "a.h[1]", "a.h[0]", "a.h", "a.e.f", "a.e", "a.b", "a"]
The top level object(s) are matched by the empty needle ""
.
Useful for matching objects nested in arrays by setting useArraySelector
to false
.
Note that the empty string does not work with _.get and _.set.
The following Characters are considered special and need to
be escaped if they should be matched in a key: [
, ]
, {
, }
, ,
, .
, !
, ?
and *
.
Conceptually this package works as follows:
-
During initialization the needles are parsed and built into a search tree. Various information is pre-computed and stored for every node. Finally the search function is returned.
-
When the search function is called, the input is traversed simultaneously with the relevant nodes of the search tree. Processing multiple search tree branches in parallel allows for a single traversal of the input.
Having a separate initialization stage allows for a performant search and significant speed ups when applying the same search to different input.