jsonq

jsonq

• A json query library written in golang

Function

• Select object and array by tokens
• Select by selectors (jsonq version)
• Return a multi-layers object (only support to return an array now)

Install

# use go get
go get github.com/Aoi-hosizora/jsonq

# use go mod
# import "github.com/Aoi-hosizora/jsonq"
go mod tidy

Usage

• see jsonq_test.go and types_test.go for details

doc, err := jsonq.NewJsonDocument(objDoc)
if err != nil {
    log.Fatalln(err)
}
jq := jsonq.NewJsonQuery(doc)

// m[1]
val, err := jq.Select(1)
// m[:]
val, err := jq.Strings(jsonq.All()) // *
// m[len(m)-2][0]
val, err := jq.Int64(-2, 0)
// m["a"]["0"]["b"]
val, err := jq.Select("a", "0", "b")
// m["a"][0]["b"][0:2]
val, err := jq.Select("a", 0, "b", jsonq.Multi(0, 1)) // #0+#1
// m[1]["*"]["a"]["2"][0/2][:]
val, err := jq.SelectBySelector("#1 \\* a 2 #0+#2 *")

Selector

• A convenient language to select json
• Grammar definition

selector := mtok        // multi token

mtok     := mtok mtok   // the next layer
mtok     := *           // all fields in the current layer
mtok     := mtok+stok   // multiple fields in the current layer
mtok     := stok        // single token
stok     := token       // string or number

token    := #numbers    // array index
token    := strings     // map key

• Rules: (WS means whitespace)
  • use WS to split layers
  • use + to split fields
  • use * to represent all fields (could not use with +)
  • use \ to escape all tokens (especially for WS + # *)
  • use #numbers as an array index (token start with #)
  • use raw number and other string as a map field name
  • if a field name starts with # or *, use \# and \* (if # and * is inside string, it is not necessary to escape)
  • if a field name includes a WS or +, use \WS and \+
• Example

token1 #2 token3+token4 #5+#6 token7\ \+\ 8 9 #10 \#0# #-1
-> "token1", 2, {"token3", "token4"}, {5, 6}, "token7 + 8", "9", 10, "#0#", -1

123123 #000 \\456 \789 \##### * \* \\**\\*+\**\\*+\*+\#+\##\#
-> "123123", 0, "\456", "789", "#####", *, "*", {"*\*", "**\*", "*", "#", "###"}

0 #1 #2+#3 #4+#5+#6 \#+#0+\###\++\#+\+##
-> "0", 1, {2, 3}, {4, 5, 6}, {"#", 0, "###+", "#", "+##"}

References

• jmoiron/jsonq
• Handwritten Parsers & Lexers in Go