How to Store Arrays of Integers in a GORM Model Using PostgreSQL?

Adding an Array of Integers to a Gorm Model Using a Custom Data Type

In the Go programming language, GORM is a popular ORM (object-relational mapper) framework for working with databases. When working with a relational database like PostgreSQL, it's often necessary to store collections of values in a single field, known as an array.

Problem: Panicking When Adding an Array of Integers

When attempting to add an array of integers []int64 to a Gorm model field, one might encounter the error: "panic: invalid sql type (slice) for postgres." This error occurs because Gorm cannot automatically map a slice to a database field.

Solution: Using a Custom Data Type for Arrays

To resolve this issue, it's necessary to use a custom data type provided by the underlying database library. In the case of PostgreSQL, the pq library offers a way to represent an integer array as a custom type pq.Int64Array for the DeckType field in the Gorm model:

<code class="go">type Game struct {                                           
        gorm.Model                                           
        GameCode    string                                      
        GameName    string                                      
        DeckType    pq.Int64Array `gorm:&quot;type:integer[]&quot;`
        GameEndDate string    
}</code>

In the gorm tag, type:integer[] specifies that this field should be treated as an array of integers in the database.

Example Insertion with an Integer Array

To insert an array of integers into a Gorm model, one can use the following syntax:

<code class="go">dt := []int64{1, 2, 3}   
                                                                                
db.Create(&amp;Game{GameCode: &quot;xxx&quot;, GameName: &quot;xxx&quot;, DeckType: pq.Int64Array(dt), GameEndDate: &quot;xxx&quot;})  </code>

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