[GitHub] [trafficcontrol] rob05c opened a new issue #3494: Change TO Large Selects to Embed Non-Struct Fields for Sqlx

[GitBox <gi...@apache.org>]

rob05c opened a new issue #3494: Change TO Large Selects to Embed Non-Struct Fields for Sqlx
URL: https://github.com/apache/trafficcontrol/issues/3494
 
 
   So, we went through all this debate about adding the massive `sqlx` library for its one `StructScan` function, to avoid things like:
   
   ```
   	resultRows, err := tx.Query(insertQuery(), &ds.Active, &ds.AnonymousBlockingEnabled, &ds.CacheURL, &ds.CCRDNSTTL, &ds.CDNID, &ds.CheckPath, &ds.ConsistentHashRegex, &deepCachingType, &ds.DisplayName, &ds.DNSBypassCNAME, &ds.DNSBypassIP, &ds.DNSBypassIP6, &ds.DNSBypassTTL, &ds.DSCP, &ds.EdgeHeaderRewrite, &ds.GeoLimitRedirectURL, &ds.GeoLimit, &ds.GeoLimitCountries, &ds.GeoProvider, &ds.GlobalMaxMBPS, &ds.GlobalMaxTPS, &ds.FQPacingRate, &ds.HTTPBypassFQDN, &ds.InfoURL, &ds.InitialDispersion, &ds.IPV6RoutingEnabled, &ds.LogsEnabled, &ds.LongDesc, &ds.LongDesc1, &ds.LongDesc2, &ds.MaxDNSAnswers, &ds.MidHeaderRewrite, &ds.MissLat, &ds.MissLong, &ds.MultiSiteOrigin, &ds.OriginShield, &ds.ProfileID, &ds.Protocol, &ds.QStringIgnore, &ds.RangeRequestHandling, &ds.RegexRemap, &ds.RegionalGeoBlocking, &ds.RemapText, &ds.RoutingName, &ds.SigningAlgorithm, &ds.SSLKeyVersion, &ds.TenantID, &ds.TRRequestHeaders, &ds.TRResponseHeaders, &ds.TypeID, &ds.XMLID)
   ```
   
   And we're not even avoiding them. The worse ones are still using the standard library:
   
   https://github.com/apache/trafficcontrol/blob/master/traffic_ops/traffic_ops_golang/deliveryservice/deliveryservicesv13.go#L143
   
   Because we need fields not in the struct, and `sqlx` isn't capable of that. Note the `&deepCachingType` in the above query.
   
   But this is possible, and not even that difficult. All we have to do is create a new struct, which anonymously embeds the real struct. Like so:
   
   ```
   type CreateDS struct {
     tc.DeliveryServiceNullable
     DeepCachingType string
   }
   createDS := &CreateDS{DeliveryServiceNullable: ds, DeepCachingType: deepCachingType}
   resultRows, err := tx.StructScan(insertQuery(), createDS)
   ds = &updateDS.DeliveryServiceNullable
   ```
   
   As well as updating `insertQuery()` to use `sqlx` `active=:active` syntax rather than standard SQL `active=$1`.
   
   In this particular case, it's also possible to solve the problem by making `tc.DeliveryService.DeepCachingType` implement `sql.Valuer` and `sql.Scanner`; but the above solution works universally.
   
   In fact, it would probably take less time to do, than it took me to make this issue.

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