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119 lines
2.7 KiB
Go
119 lines
2.7 KiB
Go
package db
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import (
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"crypto/rand"
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"encoding/hex"
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"reflect"
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"strings"
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)
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func randomHex(len int) string {
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buff := make([]byte, len/2+1)
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rand.Read(buff)
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str := hex.EncodeToString(buff)
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return str[:len]
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}
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func fieldInfo(fieldTyp reflect.StructField) (bool, string, reflect.Type, string) {
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fieldName := fieldTyp.Name
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columnName, ok := fieldTyp.Tag.Lookup("db")
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if !ok {
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columnName = strings.ToLower(fieldName)
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}
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if ok && columnName[len(columnName)-1] == '*' {
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return true, fieldName, fieldTyp.Type, columnName[:len(columnName)-1]
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}
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return false, fieldName, fieldTyp.Type, columnName
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}
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func fieldPrimaryKey(fieldTyp reflect.StructField) bool {
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isPK, _, _, _ := fieldInfo(fieldTyp)
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return isPK
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}
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// structDatabaseColumnValues takes a pointer to a struct and returns a pair
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// of slices, one with the column names and the other with pointers to all
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// its exported fields.
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//
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// The column name can be changed using the "db" tag attribute on that field
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func structDatabaseColumnValues(s any) ([]string, []any) {
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v := reflect.ValueOf(s).Elem()
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numFields := v.NumField()
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names := []string{}
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values := []any{}
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for i := 0; i < numFields; i++ {
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fieldTyp := v.Type().Field(i)
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fieldVal := v.Field(i)
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if fieldTyp.IsExported() {
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key := strings.ToLower(fieldTyp.Name)
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if name, ok := fieldTyp.Tag.Lookup("db"); ok {
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key = name
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// primary key has a "*" at the end, exclude from column name
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if key[len(key)-1] == '*' {
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key = key[:len(key)-1]
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}
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}
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names = append(names, key)
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values = append(values, fieldVal.Addr().Interface())
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}
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}
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return names, values
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}
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func structPrimaryKeyPtr(s any) (*string, bool) {
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v := reflect.ValueOf(s).Elem()
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for i := 0; i < v.NumField(); i++ {
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fieldTyp := v.Type().Field(i)
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fieldVal := v.Field(i)
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if fieldTyp.IsExported() {
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if fieldPrimaryKey(fieldTyp) {
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// SAFETY: this is required to cast *Ref[T] to *string, internally
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// they are the same type so this should be safe
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ptr := fieldVal.Addr().UnsafePointer()
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return (*string)(ptr), true
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}
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}
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}
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return nil, false
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}
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// structDatabasePrimaryKeyColumn takes a pointer to a struct and returns the
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// name of the field with the primary key
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func structDatabasePrimaryKeyColumn(s any) (field, column string, ok bool) {
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v := reflect.ValueOf(s).Elem()
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for i := 0; i < v.NumField(); i++ {
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fieldTyp := v.Type().Field(i)
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if fieldTyp.IsExported() {
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key := fieldTyp.Name
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if value, ok := fieldTyp.Tag.Lookup("db"); ok {
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if value[len(value)-1] == '*' {
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return key, value[:len(value)-1], true
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}
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}
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}
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}
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return "", "", false
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}
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func repeatSlice[T any](value T, count int) []T {
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s := make([]T, count)
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for i := 0; i < count; i++ {
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s[i] = value
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}
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return s
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}
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