Query String

LiteJS data layer comes with powerful quering features. Same queries can be used with http requests to backend and with cached model in UI.

Typical URL containing a query string is as follows:

http://example.com/items?name=ferret
                         └┬─┘│└──┬─┘
               field ─────┘  │   └───── value
            operator ────────┘

Query strings can be combined and grouped, eg. ?name=1&(a>1|b<2)

Field

A field is also usable in getter and can be a pointer:

• to direct or nested object property, eg. name or deep.nest.obj
• with type check for array or object, eg. arr[] or map{}
• to array member by id, eg arr[0] or arr[-5] from the end
• to array or object first member that matches subfilter, eg arr[id=123].name or map{id=123}.name
• to array or object length, eg arr[@] or map{@}
• to object keys, eg map{*}

Operator

List of operators:

• = - loose comparisons (==)
  a=1 matches to number 1, string "1" and boolean true, a=[ab] case insensitive glob
• == - strict comparisons (===)
  a==1 matches to number 1, a=="1" matches to string "1", a==true matches to boolean true, a==[ab] case sensitive glob
• !=, !==, >, >=, <, <=

Value

A value can be:

• loose value, eg. 1,ab,true,null
• a string, eg. "ab","true","null"
• a glob, eg a[bc]*?
  • * matches 0 or more characters
  • ? matches 1 character
  • […] matches a range of characters. If the first character of the range is ! or ^ then it matches any character not in the range.
  • in strict comparison glob is case sensitive
• a subfilter, eg, {type=x}
• a pointer to another value, eg. @other.nested.value

Multiple values can be combined with a comma ,, eg. i=1,2. A strict comparisons with a glob is case sensitive, a loose comparisons is case insensitive.

Examples

• ?field - is Truthy
• ?!field - is Falsy
• ?field=1,"a b" - number 1 or string a b
• ?field=*[bc]* - containt b or c
• ?field="*[bc]*" - is a string *[bc]*
• ?x.temp>@x.maxTemp - x.temp is greater than x.maxTemp on same object
• ?x={temp>@maxTemp} - same as previous with subfilter
• ?arr[] - have array arr
• ?arr[0]=="1" - array first element is "1"
• ?arr[@]<=3 - have array arr with 3 or less members
• ?arr[]=1 - have array that contains 1 or "1"
• ?arr[]==1 - .. contains 1
• ?arr[]={a=1|b=2} - .. contains object with a=1 or b=2
• ?arr[id=123].code==1 - first object in array with id 123 have code 1
• ?map{} - have object map
• ?map{@}>5 - have object map with more than 5 keys