From 43dfd41e5d2a5f6acd1dd75d00db8f04f2ccde1e Mon Sep 17 00:00:00 2001
From: Helmut Merz <helmutm@cy55.de>
Date: Fri, 12 Apr 2024 14:06:58 +0200
Subject: [PATCH] parameterize where clause operators and order by 'desc'
 attribute

---
 storage/tracking/sql_code.go | 13 +++++++-----
 storage/tracking/tracking.go | 41 +++++++++++++++++++++---------------
 2 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/storage/tracking/sql_code.go b/storage/tracking/sql_code.go
index 295d7a3..3f77948 100644
--- a/storage/tracking/sql_code.go
+++ b/storage/tracking/sql_code.go
@@ -44,11 +44,14 @@ insert into {{ $tablename }} (
 select {{ range $j, $c := .Scols -}}
     {{- if ne $j 0 -}}, {{ end }}{{ toLower $c }}{{- end }}
   from {{ .Table }}
-  where {{ range $j, $c := .Qucols -}}
-    {{- if ne $j 0 }} and {{ end }}{{ toLower $c }} = ${{ add1 $j }}{{- end }}
-  {{ with .Ordcols -}}
-  order by {{ range $j, $c := . -}}
-    {{- if ne $j 0 -}}, {{ end }}{{ toLower $c }}{{- end -}}
+  where {{ range $j, $s := .Quspecs -}}
+    {{- if ne $j 0 }} and {{ end -}}
+	{{- toLower $s.Col }} {{ $s.Op }} ${{ add1 $j }}{{ end }}
+  {{ with .Ordspecs -}}
+  order by {{ range $j, $s := . -}}
+    {{- if ne $j 0 -}}, {{ end }}{{ toLower $s.Col }}
+	{{- if $s.Desc }} desc{{ end }}
+	{{- end -}}
   {{- end }}
   {{ with .Limit }}limit {{ . }}{{ end }}
 `
diff --git a/storage/tracking/tracking.go b/storage/tracking/tracking.go
index 4b75798..04592c5 100644
--- a/storage/tracking/tracking.go
+++ b/storage/tracking/tracking.go
@@ -93,7 +93,23 @@ func Tracks(db *sql.Storage) *Container {
 	return &Container{container_definition, db}
 }
 
-func (cont *Container) setupQuerySpec(spec *querySpec) *querySpec {
+type querySpec struct {
+	Table           string
+	Headvals        lib.StrSlice
+	Scols           lib.StrSlice
+	Qucols, Ordcols lib.StrSlice
+	Quspecs         []struct{ Col, Op string }
+	Ordspecs        []ordSpec
+	Limit           int
+	Quvals          []any
+}
+
+type ordSpec struct {
+	Col  string
+	Desc bool
+}
+
+func (spec *querySpec) setup(cont *Container) {
 	if cont.Storage.Schema == "" {
 		spec.Table = cont.TableName
 	} else {
@@ -108,21 +124,12 @@ func (cont *Container) setupQuerySpec(spec *querySpec) *querySpec {
 			spec.Quvals = append(spec.Quvals, v)
 		}
 	}
-	return spec
-}
-
-type querySpec struct {
-	Table           string
-	Headvals        lib.StrSlice
-	Scols           lib.StrSlice
-	Qucols, Ordcols lib.StrSlice
-	Quspecs         []struct{ col, op string }
-	Ordspecs        []struct {
-		Col  string
-		Desc bool
+	for _, c := range spec.Qucols {
+		spec.Quspecs = append(spec.Quspecs, struct{ Col, Op string }{c, "="})
+	}
+	for _, c := range spec.Ordcols {
+		spec.Ordspecs = append(spec.Ordspecs, ordSpec{c, false})
 	}
-	Limit  int
-	Quvals []any
 }
 
 func (cont *Container) Get(id lib.Ident) *Track {
@@ -136,9 +143,9 @@ func (cont *Container) Get(id lib.Ident) *Track {
 func (cont *Container) QueryLast(hv ...string) *Track {
 	quSpec := &querySpec{
 		Headvals: hv,
-		Ordcols:  lib.StrSlice{"timestamp"},
 		Limit:    1,
 	}
+	quSpec.Ordspecs = append(quSpec.Ordspecs, ordSpec{"timestamp", true})
 	return cont.QueryOne(quSpec)
 }
 
@@ -149,7 +156,7 @@ func (cont *Container) QueryOne(quSpec *querySpec) *Track {
 		tr = cont.ItemFactory(cont)
 		return tr.ScanP(r)
 	}
-	cont.setupQuerySpec(quSpec)
+	quSpec.setup(cont)
 	sql := storage.BuildSql(SqlSelect, quSpec)
 	db.Query(proc, sql, quSpec.Quvals...)
 	return tr