Access nested map

Getting Help
1

hello folks,
I have a json file and I am accessing the same and trying to convert to struct using json.Unmarshal while doing so I have nested key value pairs in the json. How do I access nested map specifically the “tables” the non nested is straight forward. Please help

My json looks like
cat http1.json
{
“deviceGroup”: “none”,
“fullPath”: “/Common/top”,
“inheritedDevicegroup”: “true”,
“inheritedTrafficGroup”: “true”,
“tables”: [
{
“name”: “basic__snatpool_members”
},
{
“name”: “net__snatpool_members”
},
{
“name”: “optimizations__hosts”
},
{
“columnNames”: [
“name”
],

}

========function here

func dataToIapp(name string, d *schema.ResourceData) bigip.Iapp {
var p bigip.Iapp

var obj map[string]interface{}

jsonblob := []byte(d.Get("jsonfile").(string))
err := json.Unmarshal(jsonblob, &obj)
if err != nil {
	fmt.Println("error", err)
}

log.Printf("value of +++++++++++++++++++++++++++++all objects %+v\n p ", obj)
p.Name = obj[“name”].(string)
p.Partition = obj[“partition”].(string)
p.Devicegroup = obj[“deviceGroup”].(string)
p.InheritedDevicegroup = obj[“inheritedDevicegroup”].(string)
p.Tables = obj[“tables”].(string)

when I compile I get this error
go build

bigip/resource_bigip_sys_iapp.go:319:11: cannot use obj[“tables”].(string) (type string) as type []bigip.Tablesrecord in assignment

my struct is as below

package bigip

import (
“encoding/json”
//“log”
)

// LIC contains device license for BIG-IP system.

type Iapps struct {
Iapps []Iapp json:"items"
}

type Iapp struct {
Name string
Partition string
Description string
Devicegroup string
ExecuteAction string
InheritedDevicegroup string
StrictUpdates string
Template string
TemplateModified string
TemplatePrerequisiteErrors string
TrafficGroup string
InheritedTrafficGroup string
Lists []Listsrecord
Metadata []Metadatarecord
Tables []Tablesrecord
Variables []Variablesrecord
Jsonfile string
}
type iappDTO struct {
Name string json:"name,omitempty"
Partition string json:"partition,omitempty"
Description string json:"description,omitempty"
Devicegroup string json:"deviceGroup,omitempty"
ExecuteAction string json:"executeAction,omitempty"
InheritedDevicegroup string json:"inheritedDevicegroup,omitempty"
InheritedTrafficGroup string json:"inheritedTrafficGroup,omitempty"
StrictUpdates string json:"strictUpdates,omitempty"
Template string json:"template,omitempty"
TemplateModified string json:"templateModified,omitempty"
TemplatePrerequisiteErrors string json:"templatePrerequisiteErrors,omitempty"
TrafficGroup string json:"trafficGroup,omitempty"
Jsonfile string json:"apiAnonymous,omitempty"

Lists                      struct {
	Items []Listsrecord `json:"items,omitempty"`
} `json:"listsReference,omitempty"`
Metadata struct {
	Items []Metadatarecord `json:"items,omitempty"`
} `json:"metadataReference,omitempty"`
Tables struct {
	Items []Tablesrecord `json:"items,omitempty"`
} `json:"tablesReference,omitempty"`
Variables struct {
	Items []Variablesrecord `json:"items,omitempty"`
} `json:"variablesReference,omitempty"`

}

type Listsrecord struct {
Encrypted string json:"encrypted"
Value string json:"value"
}

type Metadatarecord struct {
Persist string json:"persist"
Value string json:"value"
}

type Tablesrecord struct {
ColumnNames string json:"columnNames"
Name string json:"name"
EncryptedColumns string json:"encryptedColumns"
Rows string json:"rows"
}

type Variablesrecord struct {
Encrypted string json:"encrypted"
Name string json:"name"
Value string json:"value"
}

2

I’m new to Go, so I don’t know if this is a good practice. I would make 3 structs, 2 for your two tables, and 1 that contains your two tables.

type metaData struct{
deviceGroup string json:“deviceGroup”
…
table1 Table1 json:"table1"
table2 Table2 json:“table2”
}

type table1 struct{
key string json:“key”
…
}

type table2 struct{
key string json:“key”
…
}

3

Hi @scshitole, For me, You can parse the JSON into an interface{} instead of a struct. In your JSON it contains a variety of structure situations. here is my code example.

var your_json = []byte(`{"name":"Miracle","project":[{"another":"assignment"}]}`)

func main() {

var obj interface{} // Parse json into an interface{}

err := json.Unmarshal(your_json,&obj)
if err != nil {
	fmt.Println(err)
}

m := obj.(map[string]interface{}) // Important: to access property
fmt.Println(m["name"])
fmt.Println(m["project"])

}

// Output:
// Miracle
// [map[another:assignment]]

Take note, You we’ll get an error “invalid character ‘:’ after array element” if your project contains like this “project: [“another”:“assignment”]”, you should add your data into a map “project: [{“another”:“assignment”}]”.

4

@adriel

Thanks Its giving me assertion type message when I compile.

go build

bigip/resource_bigip_sys_iapp.go:316:10: cannot use m[“name”] (type interface {}) as type string in assignment: need type assertion
bigip/resource_bigip_sys_iapp.go:317:14: cannot use m[“partition”] (type interface {}) as type string in assignment: need type assertion
bigip/resource_bigip_sys_iapp.go:320:11: cannot use m[“tables”] (type interface {}) as type []bigip.Tablesrecord in assignment: need type assertion

func dataToIapp(name string, d *schema.ResourceData) bigip.Iapp {
var p bigip.Iapp

var obj interface{}

jsonblob := []byte(d.Get("jsonfile").(string))
err := json.Unmarshal(jsonblob, &obj)
if err != nil {
	fmt.Println("error", err)
}

log.Printf("value of +++++++++++++++++++++++++++++all objects %+v\n p ", obj)
m := obj.(map[string]interface{}) // Important: to access property
p.Name = m[“name”]
p.Partition = m[“partition”]
//p.Devicegroup = obj[“deviceGroup”].(string)
//p.InheritedDevicegroup = obj[“inheritedDevicegroup”].(string)
p.Tables = m[“tables”]

5

@adriel

I updated with assertion
m := obj.(map[string]interface{}) // Important: to access property
p.Name = m[“name”].(string)
p.Partition = m[“partition”].(string)
//p.Devicegroup = obj[“deviceGroup”].(string)
//p.InheritedDevicegroup = obj[“inheritedDevicegroup”].(string)
p.Tables = m[“tables”].(string)

go build
bigip/resource_bigip_sys_iapp.go:320:11: cannot use m[“tables”].(string) (type string) as type []bigip.Tablesrecord in assignment

The error has gone for “name” and “partition” however but I cannot use m[“tables”].(string)

6

@adriel
I want to populate the struct Iapp with the JSON so I am trying to read the key values and assign it to stuct fields like p.Tables, p. Partition, p.Tables and so on … where p is bigip.Iapp and Iapp is as below

type Iapp struct {
Name string
Partition string
Description string
Devicegroup string
ExecuteAction string
InheritedDevicegroup string
StrictUpdates string
Template string
TemplateModified string
TemplatePrerequisiteErrors string
TrafficGroup string
InheritedTrafficGroup string
Lists []Listsrecord
Metadata []Metadatarecord
Tables []Tablesrecord
Variables []Variablesrecord
Jsonfile string
}
type iappDTO struct {
Name string json:"name,omitempty"
Partition string json:"partition,omitempty"
Description string json:"description,omitempty"
Devicegroup string json:"deviceGroup,omitempty"
ExecuteAction string json:"executeAction,omitempty"
InheritedDevicegroup string json:"inheritedDevicegroup,omitempty"
InheritedTrafficGroup string json:"inheritedTrafficGroup,omitempty"
StrictUpdates string json:"strictUpdates,omitempty"
Template string json:"template,omitempty"
TemplateModified string json:"templateModified,omitempty"
TemplatePrerequisiteErrors string json:"templatePrerequisiteErrors,omitempty"
TrafficGroup string json:"trafficGroup,omitempty"
Jsonfile string json:"apiAnonymous,omitempty"

Lists                      struct {
	Items []Listsrecord `json:"items,omitempty"`
} `json:"listsReference,omitempty"`
Metadata struct {
	Items []Metadatarecord `json:"items,omitempty"`
} `json:"metadataReference,omitempty"`
Tables struct {
	Items []Tablesrecord `json:"items,omitempty"`
} `json:"tablesReference,omitempty"`
Variables struct {
	Items []Variablesrecord `json:"items,omitempty"`
} `json:"variablesReference,omitempty"`

}

type Listsrecord struct {
Encrypted string json:"encrypted"
Value string json:"value"
}

type Metadatarecord struct {
Persist string json:"persist"
Value string json:"value"
}

type Tablesrecord struct {
ColumnNames string json:"columnNames"
Name string json:"name"
EncryptedColumns string json:"encryptedColumns"
Rows string json:"rows"
}

type Variablesrecord struct {
Encrypted string json:"encrypted"
Name string json:"name"
Value string json:"value"
}

func (p *Iapp) MarshalJSON() ([]byte, error) {
return json.Marshal(iappDTO{
Name: p.Name,
Partition: p.Partition,
Description: p.Description,
Devicegroup: p.Devicegroup,
ExecuteAction: p.ExecuteAction,
InheritedDevicegroup: p.InheritedDevicegroup,
StrictUpdates: p.StrictUpdates,
Template: p.Template,
TemplateModified: p.TemplateModified,
TemplatePrerequisiteErrors: p.TemplatePrerequisiteErrors,
TrafficGroup: p.TrafficGroup,
InheritedTrafficGroup: p.InheritedTrafficGroup,
Lists: struct {
Items []Listsrecord json:"items,omitempty"
}{Items: p.Lists},
Metadata: struct {
Items []Metadatarecord json:"items,omitempty"
}{Items: p.Metadata},
Tables: struct {
Items []Tablesrecord json:"items,omitempty"
}{Items: p.Tables},
Variables: struct {
Items []Variablesrecord json:"items,omitempty"
}{Items: p.Variables},
})
}

func (p *Iapp) UnmarshalJSON(b []byte) error {
var dto iappDTO
err := json.Unmarshal(b, &dto)
if err != nil {
return err
}

p.Name = dto.Name
p.Partition = dto.Partition
p.Description = dto.Description
p.Devicegroup = dto.Devicegroup
p.ExecuteAction = dto.ExecuteAction
p.InheritedDevicegroup = dto.InheritedDevicegroup
p.StrictUpdates = dto.StrictUpdates
p.Template = dto.Template
p.TemplateModified = dto.TemplateModified
p.TemplatePrerequisiteErrors = dto.TemplatePrerequisiteErrors
p.TrafficGroup = dto.TrafficGroup
p.InheritedTrafficGroup = dto.InheritedTrafficGroup
p.Lists = dto.Lists.Items
p.Metadata = dto.Metadata.Items
p.Tables = dto.Tables.Items
p.Variables = dto.Variables.Items

return nil

}

7

When the JSON unmarshaled, the values in JSON are converted into the following Go types: string, bool, float64 or map[string]interface{}, nil etc…, so I suggest to do a function that recursively walking the parsed JSON.

func printjson(your_json interface{}) {
	switch json_type := your_json.(type) {
		case string:
			//... You can print the value here, or return it as value.
		case float64:
			//...
		case []interface{}:
			//...
		case map[string]interface{}:
			for index, json_value := range json_type {
				printjson(json_value)
			} 
		default:
			fmt.Println("Unknown type.")
	}
}

With this function, you can do another assertion to get the value, but you need to add return type in printjson. Hope this will help to you.

8

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