70 lines
1.8 KiB
Go
70 lines
1.8 KiB
Go
package cassandra
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import (
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"fmt"
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"reflect"
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"github.com/scylladb/gocqlx/v3/table"
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)
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// GenerateTableMetadata 根據傳入的 struct 產生 table.Metadata
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func GenerateTableMetadata(document any, keyspace string) (table.Metadata, error) {
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// 取得型別資訊，若是指標則取 Elem
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t := reflect.TypeOf(document)
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if t.Kind() == reflect.Ptr {
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t = t.Elem()
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}
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// 取得表名稱：若 model 有實作 TableName() 則使用該方法，否則轉換型別名稱為 snake_case
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var tableName string
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if tm, ok := document.(interface{ TableName() string }); ok {
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tableName = fmt.Sprintf("%s.%s", keyspace, tm.TableName())
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} else {
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return table.Metadata{}, fmt.Errorf("failed to get table func")
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}
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columns := make([]string, 0, t.NumField())
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partKeys := make([]string, 0, t.NumField())
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sortKeys := make([]string, 0, t.NumField())
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// 遍歷所有 exported 欄位
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for i := 0; i < t.NumField(); i++ {
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field := t.Field(i)
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// 跳過 unexported 欄位
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if field.PkgPath != "" {
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continue
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}
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// 如果欄位有標記 db:"-" 則跳過
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if tag := field.Tag.Get("db"); tag == "-" {
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continue
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}
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// 取得欄位名稱
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colName := field.Tag.Get("db")
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if colName == "" {
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colName = toSnakeCase(field.Name)
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}
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columns = append(columns, colName)
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// 若有 partition:"true" 標記，加入 PartKey
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if field.Tag.Get("partition_key") == "true" {
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partKeys = append(partKeys, colName)
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}
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// 若有 sort:"true" 標記，加入 SortKey
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if field.Tag.Get("clustering_key") == "true" {
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sortKeys = append(sortKeys, colName)
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}
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}
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if len(partKeys) == 0 {
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return table.Metadata{}, fmt.Errorf("no partition key defined in struct")
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}
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// 組合 Metadata
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meta := table.Metadata{
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Name: tableName,
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Columns: columns,
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PartKey: partKeys,
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SortKey: sortKeys,
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}
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return meta, nil
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}
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