FlexObj makes storing the nested objects as easy as PHP associative array and it maintains the insertion order. It is most useful when handling the SQL database result set in golang.
I wanted to store the SQL database result set as a list of the nested objects in golang while maintaining the insertion order (especially when generating the reports). Then, outputs the data as a JSON string to the browser (JavaScript). Go's built-in hashmap does not keep the insertion order and require type assertion when retrieving the nested objects (which makes the codes look more verbose). So, I builded this tool to resolve my needs.
- Maintain the insertion order
- Output a FlexObj instance as a JSON string (MarshalJSON implements Marshaler)
- Decode from a FlexObj instance to a struct (could be used to ensure the correct data type is used)
- Deep clone from a FlexObj instance
- Insertion-order iteration over the FlexObj instance
- No type assertion is required when retrieving a nested object
- Go 1.11 Modules support
- Download and install FlexObj:
$ go get -u github.com/junxie6/flexobj- Import FlexObj in your code:
import (
"github.com/junxie6/flexobj"
)exampleSetPrimitiveType.go:
package main
import (
"fmt"
)
import (
"github.com/junxie6/flexobj"
)
func main() {
data := flexobj.New()
data.Set("ExamID", 1)
data.Set("ExamName", "this is a 2018 exam")
data.Set("IsDone", false)
// Print data in JSON format
fmt.Printf("Output: %s\n", data.JSONPretty())
}JSON output:
{
"ExamID": 1,
"ExamName": "this is a 2018 exam",
"IsDone": false
}exampleSetHashMap.go:
package main
import (
"fmt"
)
import (
"github.com/junxie6/flexobj"
)
func main() {
data := flexobj.New()
user := flexobj.New()
user.Set("UserID", 5)
user.Set("UserName", "Bot 1")
data.SetObj("User", user)
// Print data in JSON format
fmt.Printf("Output: %s\n", data.JSONPretty())
}JSON output:
{
"User": {
"UserID": 5,
"UserName": "Bot 1"
}
}exampleSetOrderedMap.go:
package main
import (
"fmt"
)
import (
"github.com/junxie6/flexobj"
)
func main() {
data := flexobj.New()
questionArr := flexobj.New()
data.SetArr("QuestionArr", questionArr)
q1 := flexobj.New()
q1.Set("QuestionID", 1)
q1.Set("QuestionName", "What is the best programming language?")
questionArr.SetObj("1", q1)
q2 := flexobj.New()
q2.Set("QuestionID", 2)
q2.Set("QuestionName", "What is the best editor?")
questionArr.SetObj("2", q2)
// Print data in JSON format
fmt.Printf("Output: %s\n", data.JSONPretty())
}JSON output:
{
"QuestionArr": [
{
"QuestionID": 1,
"QuestionName": "What is the best programming language?"
},
{
"QuestionID": 2,
"QuestionName": "What is the best editor?"
}
]
}exampleDatabaseResultSet.go:
package main
import (
"fmt"
)
import (
"github.com/junxie6/flexobj"
)
func main() {
// Simulating a database result set
sqlRow := []struct {
ExamID uint32
ExamName string
QuestionID uint32
QuestionName string
ChoiceID uint32
ChoiceName string
IsSelected uint8
}{
{
ExamID: 1,
ExamName: "this is a 2018 exam",
QuestionID: 1,
QuestionName: "What is the best programming language?",
ChoiceID: 1,
ChoiceName: "Go",
IsSelected: 1,
},
{
ExamID: 1,
ExamName: "this is a 2018 exam",
QuestionID: 1,
QuestionName: "What is the best programming language?",
ChoiceID: 2,
ChoiceName: "PHP",
IsSelected: 0,
},
{
ExamID: 1,
ExamName: "this is a 2018 exam",
QuestionID: 2,
QuestionName: "What is the best editor?",
ChoiceID: 3,
ChoiceName: "Vim",
IsSelected: 1,
},
{
ExamID: 1,
ExamName: "this is a 2018 exam",
QuestionID: 2,
QuestionName: "What is the best editor?",
ChoiceID: 4,
ChoiceName: "Visual Studio Code",
IsSelected: 0,
},
}
//
flexobj.IsDebug = true
data := flexobj.New()
examID := ""
questionID := ""
choiceID := ""
for _, row := range sqlRow {
examID = flexobj.Uint32ToStr(row.ExamID)
questionID = flexobj.Uint32ToStr(row.QuestionID)
choiceID = flexobj.Uint32ToStr(row.ChoiceID)
if data.IsSet(examID) != true {
// Initialize an exam object
exam := flexobj.New()
exam.Set("ExamID", row.ExamID)
exam.Set("ExamName", row.ExamName)
exam.SetArr("QuestionArr", flexobj.New())
data.SetObj(examID, exam)
}
if questionArr := data.GetObj(examID).GetArr("QuestionArr"); questionArr.IsSet(questionID) != true {
// Initialize a question object
question := flexobj.New()
question.Set("QuestionID", row.QuestionID)
question.Set("QuestionName", row.QuestionName)
question.SetArr("ChoiceArr", flexobj.New())
questionArr.SetObj(questionID, question)
}
if choiceArr := data.GetObj(examID).GetArr("QuestionArr").GetObj(questionID).GetArr("ChoiceArr"); choiceArr.IsSet(choiceID) != true {
// Initialize a choice object
choice := flexobj.New()
choice.Set("ChoiceID", row.ChoiceID)
choice.Set("ChoiceName", row.ChoiceName)
choice.Set("IsSelected", row.IsSelected)
choiceArr.SetObj(choiceID, choice)
}
}
// Print data in JSON format
fmt.Printf("Output: %s\n", data.JSONPretty())
}JSON output:
{
"1": {
"ExamID": 1,
"ExamName": "this is a 2018 exam",
"QuestionArr": [
{
"QuestionID": 1,
"QuestionName": "What is the best programming language?",
"ChoiceArr": [
{
"ChoiceID": 1,
"ChoiceName": "Go",
"IsSelected": 1
},
{
"ChoiceID": 2,
"ChoiceName": "PHP",
"IsSelected": 0
}
]
},
{
"QuestionID": 2,
"QuestionName": "What is the best editor?",
"ChoiceArr": [
{
"ChoiceID": 3,
"ChoiceName": "Vim",
"IsSelected": 1
},
{
"ChoiceID": 4,
"ChoiceName": "Visual Studio Code",
"IsSelected": 0
}
]
}
]
}
}exampleNestedObject.go:
package main
import (
"fmt"
)
import (
"github.com/junxie6/flexobj"
)
func main() {
//
exam_ExamID := "1"
exam := flexobj.New()
exam.Set("ExamID", flexobj.StrToUint32(exam_ExamID))
exam.Set("ExamName", "this is a 2018 exam")
// QuestionArr
questionArr := flexobj.New()
exam.SetArr("QuestionArr", questionArr)
// Question 1
q1_QuestionID := "1"
q1 := flexobj.New()
questionArr.SetObj(q1_QuestionID, q1)
q1.Set("QuestionID", flexobj.StrToUint32(q1_QuestionID))
q1.Set("QuestionName", "What is the best programming language?")
// Question 1 - ChoiceArr
q1_ChoiceArr := flexobj.New()
q1.SetArr("ChoiceArr", q1_ChoiceArr)
// Question 1 - Choice 1
q1c1_ChoiceID := "1"
q1c1 := flexobj.New()
q1_ChoiceArr.SetObj(q1c1_ChoiceID, q1c1)
q1c1.Set("ChoiceID", flexobj.StrToUint32(q1c1_ChoiceID))
q1c1.Set("ChoiceName", "Go")
q1c1.Set("IsSelected", 1)
// Question 1 - Choice 2
q1c2_ChoiceID := "2"
q1c2 := flexobj.New()
q1_ChoiceArr.SetObj(q1c2_ChoiceID, q1c2)
q1c2.Set("ChoiceID", flexobj.StrToUint32(q1c2_ChoiceID))
q1c2.Set("ChoiceName", "PHP")
q1c2.Set("IsSelected", 0)
// Print exam data in JSON format
fmt.Printf("Output: %s\n", exam.JSONPretty())
}JSON output:
{
"ExamID": 1,
"ExamName": "this is a 2018 exam",
"QuestionArr": [
{
"QuestionID": 1,
"QuestionName": "What is the best programming language?",
"ChoiceArr": [
{
"ChoiceID": 1,
"ChoiceName": "Go",
"IsSelected": 1
},
{
"ChoiceID": 2,
"ChoiceName": "PHP",
"IsSelected": 0
}
]
}
]
}exampleClone.go:
package main
import (
"fmt"
)
import (
"github.com/junxie6/flexobj"
)
func main() {
// Exam
exam := flexobj.New()
exam.Set("ExamID", 123456)
exam.Set("ExamName", "this is a 2018 exam")
// Clone data
examCloned := flexobj.Clone(exam)
// Set some value
exam.Set("ExamName", "this is a 2019 exam")
// Print exam data in JSON format
fmt.Printf("exam: %s\n", exam.JSONPretty())
fmt.Printf("examCloned: %s\n", examCloned.JSONPretty())
}Output:
exam: {
"ExamID": 123456,
"ExamName": "this is a 2019 exam"
}
examCloned: {
"ExamID": 123456,
"ExamName": "this is a 2018 exam"
}
exampleIteration.go:
package main
import (
"fmt"
)
import (
"github.com/junxie6/flexobj"
)
func main() {
// Exam
exam := flexobj.New()
exam.Set("ExamID", 123456)
exam.Set("ExamName", "this is a 2018 exam")
// Interation
for ; exam.Next(); exam.Increase() {
fmt.Printf("%v: %v\n", exam.Key(), exam.Value())
}
}Output:
ExamID: 123456
ExamName: this is a 2018 exam