Reputation: 16359
Loop over nested JSON elements in Go
I am receiving a JSON response from an API that contains one or more "entities". The JSON looks like this:
{
"3211": {
"entity_id": "3211",
"status": "complete",
"coupon_code": "COUPON",
"shipping_description": "Shipping - AU Courier",
"customer_id": "2775",
"base_discount_amount": "-50.0000",
"base_grand_total": "149.0000",
"base_shipping_amount": "0.0000",
"base_shipping_tax_amount": "0.0000",
"base_subtotal": "199.0000",
"base_tax_amount": "0.0000",
"base_total_paid": "149.0000",
"base_total_refunded": null,
"discount_amount": "-50.0000",
"grand_total": "149.0000",
"shipping_amount": "0.0000",
"shipping_tax_amount": "0.0000",
"store_to_order_rate": "1.0000",
"subtotal": "199.0000",
"tax_amount": "0.0000",
"total_paid": "149.0000",
"total_refunded": null,
"base_shipping_discount_amount": "0.0000",
"base_subtotal_incl_tax": "199.0000",
"base_total_due": "0.0000",
"shipping_discount_amount": "0.0000",
"subtotal_incl_tax": "199.0000",
"total_due": "0.0000",
"increment_id": "200000423",
"base_currency_code": "AUD",
"discount_description": "COUPON",
"remote_ip": "123.123.123.123",
"store_currency_code": "AUD",
"store_name": "Australia",
"created_at": "2017-07-17 03:07:40",
"shipping_incl_tax": "0.0000",
"payment_method": "ewayrapid_ewayone",
"gift_message_from": null,
"gift_message_to": null,
"gift_message_body": null,
"tax_name": null,
"tax_rate": null,
"addresses": [
{
"region": "South Australia",
"postcode": "5000",
"lastname": "Doe",
"street": "Level 6\n25 Example Street",
"city": "Adelaide",
"email": "example@email.com",
"telephone": "+61 123 456 789",
"country_id": "AU",
"firstname": "John",
"address_type": "billing",
"prefix": null,
"middlename": null,
"suffix": null,
"company": null
},
{
"region": "South Australia",
"postcode": "5000",
"lastname": "Doe",
"street": "Level 6\n25 Example Street",
"city": "Adelaide",
"email": "example@email.com",
"telephone": "+61 123 456 789",
"country_id": "AU",
"firstname": "John",
"address_type": "shipping",
"prefix": null,
"middlename": null,
"suffix": null,
"company": null
}
]
}
}
I have written the following struct types:
type Orders map[string]Order
type Order struct {
EntityID string `json:"entity_id"`
Status string `json:"status"`
CouponCode string `json:"coupon_code"`
ShippingDescription string `json:"shipping_description"`
CustomerID string `json:"customer_id"`
BaseDiscountAmount string `json:"base_discount_amount"`
BaseGrandTotal string `json:"base_grand_total"`
BaseShippingAmount string `json:"base_shipping_amount"`
BaseShippingTaxAmount string `json:"base_shipping_tax_amount"`
BaseSubtotal string `json:"base_subtotal"`
BaseTaxAmount string `json:"base_tax_amount"`
BaseTotalPaid string `json:"base_total_paid"`
BaseTotalRefunded string `json:"base_total_refunded"`
DiscountAmount string `json:"discount_amount"`
GrandTotal string `json:"grand_total"`
ShippingAmount string `json:"shipping_amount"`
ShippingTaxAmount string `json:"shipping_tax_amount"`
StoreToOrderRate string `json:"store_to_order_rate"`
Subtotal string `json:"subtotal"`
TaxAmount string `json:"tax_amount"`
TotalPaid string `json:"total_paid"`
TotalRefunded string `json:"total_refunded"`
BaseShippingDiscountAmount string `json:"base_shipping_discount_amount"`
BaseSubtotalInclTax string `json:"base_subtotal_incl_tax"`
BaseTotalDue string `json:"base_total_due"`
ShippingDiscountAmount string `json:"shipping_discount_amount"`
SubtotalInclTax string `json:"subtotal_incl_tax"`
TotalDue string `json:"total_due"`
IncrementID string `json:"increment_id"`
BaseCurrencyCode string `json:"base_currency_code"`
DiscountDescription string `json:"discount_description"`
RemoteIP string `json:"remote_ip"`
StoreCurrencyCode string `json:"store_currency_code"`
StoreName string `json:"store_name"`
CreatedAt string `json:"created_at"`
ShippingInclTax string `json:"shipping_incl_tax"`
PaymentMethod string `json:"payment_method"`
TaxName string `json:"tax_name"`
TaxRate string `json:"tax_rate"`
Addresses map[string]OrderAddresses `json:"addresses"`
}
type OrderAddresses []struct {
Region string `json:"region"`
Postcode string `json:"postcode"`
Lastname string `json:"lastname"`
Street string `json:"street"`
City string `json:"city"`
Email string `json:"email"`
Telephone string `json:"telephone"`
CountryID string `json:"country_id"`
Firstname string `json:"firstname"`
AddressType string `json:"address_type"`
Prefix *string `json:"prefix"`
Middlename *string `json:"middlename"`
Suffix *string `json:"suffix"`
Company *string `json:"company"`
}
I am then trying to process it like so (the getFromOrdersAPI(page) function returns the JSON mentioned above in the Orders type):
for page := 1; page < 3; page++ {
orders := getFromOrdersAPI(page)
for _, order := range orders {
//Process all the order items except addresses
fmt.Println("Processing entity:", orders.EntityID)
for _, orderaddress := range order.Addresses {
//Trying to access address values - example below
fmt.Println(orderaddress.Region)
}
}
}
When running this, I get the error:
orderaddress.Region undefined (type OrderAddresses has no field or method Region)
Where am I going wrong?
Upvotes: 1
Views: 762
Answers (2)
Reputation: 9288
The reason you are getting the orderaddress.Region undefined error is because the orderaddress in your for loop is an array, based on your OrderAddresses type. Obviously, an array doesn't have fields or methods named Region.
If you want to examine what orderaddress in your for loop looks like, you can range over it like this:
for _, orderaddress := range order.Addresses {
for _, addressData := range orderaddress{
fmt.Printf("%+v\n", addressData)
}
}
I have created an example here.
That said, in your JSON data, the addresses field is an array, not a map. So the Addresses field in your Order struct must be an array too. Then your OrderAddresses should just be a struct, not a slice of struct.
Upvotes: 1
Reputation: 333
The error you are getting is due to the way you are defining your OrderAddresses struct. Instead of
type OrderAddresses []struct {
If you use
type OrderAddresses struct {
without the braces, your compile error should go away.
That being said, I'm not sure if your json will parse as you expect given the blob I'm looking at. It appears that addresses in the json blob is an array. This means that instead of representing it as
Addresses map[string]OrderAddresses `json:"addresses"`
You should simply make it a slice of OrderAddresses
Addresses []OrderAddresses `json:"addresses"`
Upvotes: 2
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