GORM无法将外键传递给查询

I am usin jinzhu GORM package for connecting to the DB, etc.

This is my code

package pizzas

import (
    "github.com/jinzhu/gorm"
    "github.com/gin-gonic/gin"
    "speedy-gonzales/db"
    "net/http"
)

type Pizza struct {
    gorm.Model
    Name                string `gorm:"not null"`
    Image               string `sql:"type:text"`
    PSizesAndPrices     []PizzaPriceSize
}

type PizzaPriceSize struct {
    gorm.Model
    SizeTitle       string      `gorm:"column:size_title;type:varchar(50);not null'"`
    PriceEur        int         `gorm:"column:price_eur"`
    PriceBam        int         `gorm:"column:price_bam"`
    PizzaID         uint        `gorm:"index"`
}

func (PizzaPriceSize) TableName() string {
    return "pizza_price_sizes"
}

func FetchPizzasWithSizes(c *gin.Context) {
    var pizza_model []Pizza

    var p_sizes_prices_model []PizzaPriceSize


    dB := db.DbConnect()
    dB.Debug().Model(&pizza_model).Related(&p_sizes_prices_model)

    c.JSON(http.StatusOK, gin.H{
        "status": http.StatusOK,
        "message": p_sizes_prices_model,
    })
    return
}

When I run the app this is what I get from debug console: SELECT * FROM pizza_price_sizes WHERE pizza_price_sizes.deleted_at IS NULL AND ((pizza_id = '0'))

My question is how can I pass pizza_id to this query?