Add relationship "to_one" template.

- Temporarily add some new helper functions, going to clean these all
  up in favor of pipes
- Annotate a couple of super weird methods
- Fix a printf verb for err

strmangle/strmangle.go

@@ -295,7 +295,8 @@ func WherePrimaryKey(pkeyCols []string, start int) string {
 	return output
 }
 
-// AutoIncPrimKey returns the auto-increment primary key column name or an empty string
+// AutoIncPrimaryKey returns the auto-increment primary key column name or an
+// empty string.
 func AutoIncPrimaryKey(cols []dbdrivers.Column, pkey *dbdrivers.PrimaryKey) string {
 	if pkey == nil {
 		return ""
@@ -315,7 +316,7 @@ func AutoIncPrimaryKey(cols []dbdrivers.Column, pkey *dbdrivers.PrimaryKey) stri
 	return ""
 }
 
-// ColumnsToString changes the columns into a list of column names
+// ColumnsToStrings changes the columns into a list of column names
 func ColumnsToStrings(cols []dbdrivers.Column) []string {
 	names := make([]string, len(cols))
 	for i, c := range cols {
@@ -353,8 +354,8 @@ func PrimaryKeyFlagIndex(regularCols []dbdrivers.Column, pkeyCols []string) int
 	return len(regularCols) - len(pkeyCols) + 1
 }
 
-// SupportsResult returns whether the database driver supports the sql.Results
-// interface, i.e. LastReturnId and RowsAffected
+// SupportsResultObject returns whether the database driver supports the
+// sql.Results interface, i.e. LastReturnId and RowsAffected
 func SupportsResultObject(driverName string) bool {
 	switch driverName {
 	case "postgres":
@@ -389,3 +390,19 @@ func FilterColumnsByAutoIncrement(columns []dbdrivers.Column) string {
 
 	return strings.Join(cols, `,`)
 }
+
+// AddID to the end of the string
+func AddID(str string) string {
+	return str + "_id"
+}
+
+// RemoveID from the end of the string
+func RemoveID(str string) string {
+	return strings.TrimSuffix(str, "_id")
+}
+
+// Substring returns a substring of str starting at index start and going
+// to end-1.
+func Substring(start, end int, str string) string {
+	return str[start:end]
+}

strmangle/testmangle.go

@@ -7,10 +7,14 @@ import (
 	"github.com/nullbio/sqlboiler/dbdrivers"
 )
 
+// RandDBStruct does nothing yet
+// TODO(nullbio): What is this?
 func RandDBStruct(varName string, table dbdrivers.Table) string {
 	return ""
 }
 
+// RandDBStructSlice randomizes a struct?
+// TODO(nullbio): What is this?
 func RandDBStructSlice(varName string, num int, table dbdrivers.Table) string {
 	var structs []string
 	for i := 0; i < num; i++ {

templates.go

@@ -84,6 +84,9 @@ func loadTemplate(dir string, filename string) (*template.Template, error) {
 // templates. If you wish to pass a new function into your own template,
 // add a function pointer here.
 var templateFunctions = template.FuncMap{
+	"tolower":                      strings.ToLower,
+	"toupper":                      strings.ToUpper,
+	"substring":                    strmangle.Substring,
 	"singular":                     strmangle.Singular,
 	"plural":                       strmangle.Plural,
 	"titleCase":                    strmangle.TitleCase,
@@ -113,6 +116,8 @@ var templateFunctions = template.FuncMap{
 	"filterColumnsByDefault":       strmangle.FilterColumnsByDefault,
 	"filterColumnsByAutoIncrement": strmangle.FilterColumnsByAutoIncrement,
 	"autoIncPrimaryKey":            strmangle.AutoIncPrimaryKey,
+	"addID":                        strmangle.AddID,
+	"removeID":                     strmangle.RemoveID,
 
 	"randDBStruct":      strmangle.RandDBStruct,
 	"randDBStructSlice": strmangle.RandDBStructSlice,

templates/find.tpl

@@ -21,7 +21,7 @@ func {{$tableNameSingular}}FindX(exec boil.Executor, {{primaryKeyFuncSig .Table.
   err := boil.ExecQueryOne(q).Scan(boil.GetStructPointers({{$varNameSingular}}, selectCols...)...)
 
   if err != nil {
-    return nil, fmt.Errorf("{{.PkgName}}: unable to select from {{.Table.Name}}: %s", err)
+    return nil, fmt.Errorf("{{.PkgName}}: unable to select from {{.Table.Name}}: %v", err)
   }
 
   return {{$varNameSingular}}, nil

templates/relationship_to_one.tpl

@@ -0,0 +1,25 @@
+{{- if .Table.IsJoinTable -}}
+{{- else -}}
+  {{- $pkg := .PkgName -}}
+  {{- $localTable := titleCaseSingular .Table.Name -}}
+  {{- range .Table.FKeys -}}
+    {{- $localColumn := .Column | removeID | titleCaseSingular -}}
+    {{- $foreignColumn := .Column | removeID | titleCaseSingular -}}
+    {{- $foreignTable := titleCaseSingular .ForeignTable -}}
+    {{- $varname := camelCaseSingular .ForeignTable -}}
+    {{- $receiver := $localTable | tolower | substring 0 1 -}}
+// {{$foreignColumn}} fetches the {{$foreignTable}} pointed to by the foreign key.
+func ({{$receiver}} *{{$localTable}}) {{$foreignColumn}}(exec boil.Executor, selectCols ...string) (*{{$foreignTable}}, error) {
+  {{$varname}} := &{{$foreignTable}}{}
+
+  query := fmt.Sprintf(`select %s from {{.ForeignTable}} where id = $1`, strings.Join(selectCols, `,`))
+  err := exec.QueryRow(query, {{$receiver}}.{{titleCase .Column}}).Scan(boil.GetStructPointers({{$varname}}, selectCols...)...)
+  if err != nil {
+    return nil, fmt.Errorf(`{{$pkg}}: unable to select from {{.ForeignTable}}: %v`, err)
+  }
+
+  return {{$varname}}, nil
+}
+
+{{end -}}
+{{- end -}}