CODEWITHSUNDEEP
gogo-map
kokoko
kokoko

Reputation: 3964

golang map not adding element

There is battleFoundmap in my code and i tried the add a element like this:(battle is not nil)

battleFoundMap[battle.ID] = battle.Answers

But when i debug it it returns 1:27: expected '==', found '=' error and not put in it. How to solve it?

Here is map and Card struct

var battleFoundMap map[uint][]models.Card

type Card struct {
    gorm.Model
    UserId             uint      `json:"userid"`
    Name               string    `json:"name"`
    Meaning            string    `json:"meaning"`
}

Upvotes: -1

Views: 2432

Answers (2)

Kamol Hasan
Kamol Hasan

Reputation: 13476

Adding to @ShivaKishore's answer,

When you declare a map like, var name map[KeyType]ValueType. The value of this map is nil and has a length of 0.

A nil map has no key-values nor can be added. It behaves like an empty map for read-operations but causes a runtime panic if you want to write data to it.

var m map[string]string

// reading
m["foo"] == "" // works.

// writing
m["foo"] = "bar" // will panic.

But, initializing a map with make creates an empty map that works with both read and write operations.

// as you can't declare a map globally using shorthands
var m map[string]string
m = make(map[string]string)

or, using shorthands

m := make(map[string]string)

Upvotes: 2

Shiva Kishore
Shiva Kishore

Reputation: 1701

You should initialise a map with make before using it.

change

var battleFoundMap map[uint][]models.Card

to

battleFoundMap := make(map[uint][]models.Card)

That should be enough.

Upvotes: 1

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