I cracked my brain trying to make my code shorter and cleaner. The problem is in one function, that is working with different structs, that implements one interface.
In some cases I need the model variable to implement the structure (slice of rowModel's) ([]rowModel) and some times I need to use methods from interface.
The code is not short, sorry for that. So I put main comments in the code below.
Here is interface:
type StatModel interface {
FilterData(Filter)
ClusterData(Filter)
CountDataForChart(string)[]ChartElement
GroupByTreeGroups(Filter)[]OrgPack
}
type StatRow interface {
Count( name string) float64
}
This interfaces are created for methods calls, and to make code shorter. But Interface cannot have fields or structure as Abstruct class in OOP. One of the models is here:
type NoaggModel []NoaggRow
type NoaggRow struct {
Date string
Hour int
Id_user int
Id_line float64
Id_region int
Id_tree_devision int
N_inb float64
N_out float64
N_hold float64
N_abandon float64
N_transfer float64
T_inb float64
T_out float64
T_hold float64
T_ring float64
T_acw float64
T_wait float64
}
type FcrModel []FcrRow
type FcrRow struct {
Date string
Hour int
Id_user int
Id_line float64
Id_region int
Id_tree_devision int
N_irr float64
N_inb float64
}
So , I'm reading from channel, and getting different structures, and trying to calculate everything correctly. How to make type assertion and method calls correctly in this case?
func receiveLightWork(org <-chan models.OrgPack, request ChartOptions) interface{} {
modelClusters := make(map[string][]models.OrgPack)
// here I fill data into modelClusters
output := make(map[string][]OrgStat)
// here I begin loop over clusters of different model types
for modelName, slice := range modelClusters {
//here I can't choose what to write
// model must be convertable to NoaggModel, that is []NoaggRow{}
// as others AcsiModel, FcrModel ...etc.
// Also model.ClusterData(customFilter) must be callable as it is in interface of common model
var model []interface{}
var rowModel interface{}
switch modelName {
case "noagg":
model = model.(models.NoaggModel)
rowModel = rowModel.(models.NoaggRow{})
case "acsi":
model = model.(models.AcsiModel)
rowModel = rowModel.(models.AcsiRow)
case "fcr24":
model = model.(models.FcrModel)
rowModel = rowModel.(models.FcrRow)
case "aic":
model = model.(models.AicModel)
rowModel = rowModel.(models.AicRow)
}
for _, el := range slice {
modelFields := reflect.ValueOf(&rowModel).Elem()
sliceFields := reflect.ValueOf(&el.SummorisedData).Elem()
fieldsTypes := modelFields.Type()
for i := 6; i < modelFields.NumField(); i++ {
fmt.Println(" model_field ", fieldsTypes.Field(i).Name )
modelField := modelFields.Field(i);
sliceField := sliceFields.Index(i-6) ;
modelField.Set(reflect.Value(sliceField));
}
id_line := sliceFields.Index(len(el.SummorisedData) - 1) ;
date := sliceFields.FieldByName("PackName");
modelFields.FieldByName("Id_line").Set(id_line)
modelFields.FieldByName("Date").Set(date)
// here append not works, because model is []interface{} and not []NoaggRow or others.
// Writes [non-interface type []interface {} on left]
model = append(model, rowModel)
}
// here I need to call interface method for model
model.ClusterData(customFilter) // now here is unresolved Reference 'ClusterData'
for _, mod := range model {
// here some common logick for creating data for chart output
}
}
return output
}
All help is very highly appreciated. I'll answer to each question on this topic if necessary.
Update 1:
Have modified few things for generating struct's on the fly. Now all is compiling correctly until the place, where I need to get instance of struct. It sees only interface.. The comments and code update is here:
func typeSwitch(model string) (interface{}, interface{}){
switch model{
case "noagg":
fmt.Println("Model type:", model)
return &models.NoaggModel{}, &models.NoaggRow{}
case "acsi":
fmt.Println("Model type:", model)
return &models.AcsiModel{}, &models.AcsiRow{}
case "fcr24":
fmt.Println("Model type:", model)
return &models.FcrModel{}, &models.FcrRow{}
case "aic":
fmt.Println("Model type:", model)
return &models.AicModel{}, &models.AicRow{}
default:
fmt.Println("Unknown")
return false,false
}
}
func receiveLightWork(org <-chan models.OrgPack, request ChartOptions) interface{} {
modelClusters := make(map[string][]models.OrgPack)
for orgPack := range org {
// here I fill data into clusters
}
output := make(map[string][]OrgStat)
// here I need common code to put data from clusters in correct structures and call interface methods
for modelName, slice := range modelClusters {
model, rowModel := typeSwitch(modelName)
var data_slice []interface{}
for _, el := range slice {
modelFields := reflect.ValueOf(rowModel).Elem()
fieldsCounter := modelFields.NumField()
sliceFields := reflect.ValueOf(&el.SummorisedData).Elem()
sliceObjFields := reflect.ValueOf(&el).Elem()
fieldsTypes := modelFields.Type()
for i := 6; i < fieldsCounter; i++ {
fmt.Println(" model_field ", fieldsTypes.Field(i).Name )
modelField := modelFields.Field(i);
sliceField := sliceFields.Index(i-6) ;
modelField.Set(reflect.Value(sliceField));
}
id_line := sliceFields.Index(len(el.SummorisedData) - 1) ;
date := sliceObjFields.FieldByName("PackName");
modelFields.FieldByName("Id_line").Set(id_line)
modelFields.FieldByName("Date").Set(date)
fmt.Println("row_data : ", rowModel)
data_slice = append(data_slice, rowModel)
}
// here comes : invalid type assertion: data_slice.(model) (non-interface type []interface {} on left
dataModel := data_slice.(model)
// here I need correctly created instance of model
// (NoaggModel or FcrModel) with data inside its struct
// to work with it and call interface methods that are shown in interface above
}
return output
}
[]interface{}is a concrete type. It's a slice; you can't do type assertions directly on it. But if you were to loop overrange data_slice, you would get aninterface{}value in each loop iteration, which you could attempt type assertions on. This should at least address the compile-time error you're seeing. – Nighttime