support basic json filtering and selection

weed/query/json/query_json.go

@@ -1,5 +1,107 @@
 package json
 
-func QueryJson(jsonLine string, query string) (jsonOutput string) {
-	return jsonLine
+import (
+	"strconv"
+
+	"github.com/chrislusf/seaweedfs/weed/query/sqltypes"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/match"
+)
+
+type Query struct {
+	Field string
+	Op    string
+	Value string
+}
+
+func QueryJson(jsonLine string, projections []string, query Query) (passedFilter bool, values []sqltypes.Value) {
+	if filterJson(jsonLine, query) {
+		passedFilter = true
+		fields := gjson.GetMany(jsonLine, projections...)
+		for _, f := range fields {
+			values = append(values, sqltypes.MakeTrusted(sqltypes.Type(f.Type), sqltypes.StringToBytes(f.Raw)))
+		}
+		return
+	}
+	return false, nil
+}
+
+func filterJson(jsonLine string, query Query) bool{
+
+	value := gjson.Get(jsonLine, query.Field)
+
+	// copied from gjson.go queryMatches() function
+	rpv := query.Value
+
+	if !value.Exists() {
+		return false
+	}
+	if query.Op == "" {
+		// the query is only looking for existence, such as:
+		//   friends.#(name)
+		// which makes sure that the array "friends" has an element of
+		// "name" that exists
+		return true
+	}
+	switch value.Type {
+	case gjson.String:
+		switch query.Op {
+		case "=":
+			return value.Str == rpv
+		case "!=":
+			return value.Str != rpv
+		case "<":
+			return value.Str < rpv
+		case "<=":
+			return value.Str <= rpv
+		case ">":
+			return value.Str > rpv
+		case ">=":
+			return value.Str >= rpv
+		case "%":
+			return match.Match(value.Str, rpv)
+		case "!%":
+			return !match.Match(value.Str, rpv)
+		}
+	case gjson.Number:
+		rpvn, _ := strconv.ParseFloat(rpv, 64)
+		switch query.Op {
+		case "=":
+			return value.Num == rpvn
+		case "!=":
+			return value.Num != rpvn
+		case "<":
+			return value.Num < rpvn
+		case "<=":
+			return value.Num <= rpvn
+		case ">":
+			return value.Num > rpvn
+		case ">=":
+			return value.Num >= rpvn
+		}
+	case gjson.True:
+		switch query.Op {
+		case "=":
+			return rpv == "true"
+		case "!=":
+			return rpv != "true"
+		case ">":
+			return rpv == "false"
+		case ">=":
+			return true
+		}
+	case gjson.False:
+		switch query.Op {
+		case "=":
+			return rpv == "false"
+		case "!=":
+			return rpv != "false"
+		case "<":
+			return rpv == "true"
+		case "<=":
+			return true
+		}
+	}
+	return false
+
 }