esqb

README

esqb

Build elasticsearch query with C-style boolean expression.

How to use

1. Use the expression to be parsed and a query factory to instanciate a queryBuilder (The queryBuilder will be instanciated only if the expression can be parsed without any problems)
2. The query factory is a 2-level map, which maps field-alias & comparator combinations to queryGenerator (a closure function). When queryGenerator is called, it will return a sub-query for the certain field with the given value.
3. Call the Build() function to finally build the query

Try it yourself

check ./query_builder_test.go

How it works

When an expression is given, it will:

1. Scan the expression and extract all tokens from it.
2. Use shunting-yard algorithm to convert these tokens to a suffix expression.
3. Parse the expression and return the final query
   • If the operator is a comparing operator and one of the operands is a field-alias, calls the queryGenerator to build a query.
   • If the operator is a logical operator and both of the operands are elastic.Query, use elastic.BoolQuery to group the sub queries.

Thanks to

1. Lexer from govaluate
2. Shunting-yard algorithm from go-shunting-yard

Documentation

Index

• Constants
• func NewQueryBuilder(expr string, queryFactory map[string]map[operator]queryGenerator) (*queryBuilder, error)
• func RangeQueryGenerators(getBaseQuery func() *elastic.RangeQuery) map[operator]queryGenerator

Constants

const (
	EQ operator
	NEQ
	GT
	LT
	GTE
	LTE
)

Functions

func NewQueryBuilder

func NewQueryBuilder(expr string, queryFactory map[string]map[operator]queryGenerator) (*queryBuilder, error)

func RangeQueryGenerators

func RangeQueryGenerators(getBaseQuery func() *elastic.RangeQuery) map[operator]queryGenerator