Use graph descent approach to pass tests
- The problem with the old approach is that it was looping over each result, and then recursing in and doing it's loading. But in reality we should only load from a table in a capacity once (tomany, toone).
This commit is contained in:
Aaron L
parent
e625589ed1
commit
718691fc53
1 changed files with 156 additions and 62 deletions
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@ -2,7 +2,6 @@ package queries
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import (
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"database/sql"
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"fmt"
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"reflect"
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"strings"
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@ -45,6 +44,9 @@ func (l loadRelationshipState) buildKey(depth int) string {
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//
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// toLoad should look like:
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// []string{"Relationship", "Relationship.NestedRelationship"} ... etc
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// obj should be one of:
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// *[]*struct or *struct
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// bkind should reflect what kind of thing it is above
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func eagerLoad(exec boil.Executor, toLoad []string, obj interface{}, bkind bindKind) error {
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state := loadRelationshipState{
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exec: exec,
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@ -72,6 +74,18 @@ func eagerLoad(exec boil.Executor, toLoad []string, obj interface{}, bkind bindK
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// - singular is passed in to identify whether or not this was a single object
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// or a slice that must be loaded into.
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// - obj is the object or slice of objects, always of the type *obj or *[]*obj as per bind.
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//
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// We start with a normal select before eager loading anything: select * from a;
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// Then we start eager loading things, it can be represented by a DAG
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// a1, a2 select id, a_id from b where id in (a1, a2)
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// / | \
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// b1 b2 b3 select id, b_id from c where id in (b2, b3, b4)
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// / | \ \
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// c1 c2 c3 c4
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//
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// That's to say that we descend the graph of relationships, and at each level
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// we gather all the things up we want to load into, load them, and then move
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// to the next level of the graph.
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func (l loadRelationshipState) loadRelationships(depth int, obj interface{}, bkind bindKind) error {
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typ := reflect.TypeOf(obj).Elem()
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if bkind == kindPtrSliceStruct {
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@ -82,51 +96,11 @@ func (l loadRelationshipState) loadRelationships(depth int, obj interface{}, bki
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if loadingFrom.IsNil() {
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return nil
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}
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loadingFrom = reflect.Indirect(loadingFrom)
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fmt.Println("load rels", typ.String(), l.toLoad[depth:])
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if !l.hasLoaded(depth) {
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fmt.Println("!loaded", l.toLoad[depth])
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current := l.toLoad[depth]
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ln, found := typ.FieldByName(loaderStructName)
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// It's possible a Loaders struct doesn't exist on the struct.
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if !found {
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return errors.Errorf("attempted to load %s but no L struct was found", current)
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if err := l.callLoadFunction(depth, loadingFrom, typ, bkind); err != nil {
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return err
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}
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// Attempt to find the LoadRelationshipName function
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loadMethod, found := ln.Type.MethodByName(loadMethodPrefix + current)
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if !found {
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return errors.Errorf("could not find %s%s method for eager loading", loadMethodPrefix, current)
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}
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// Hack to allow nil executors
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execArg := reflect.ValueOf(l.exec)
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if !execArg.IsValid() {
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execArg = reflect.ValueOf((*sql.DB)(nil))
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}
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// Get a loader instance from anything we have, *struct, or *[]*struct
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val := reflect.Indirect(loadingFrom)
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if bkind == kindPtrSliceStruct {
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val = reflect.Indirect(val.Index(0))
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}
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methodArgs := []reflect.Value{
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val.FieldByName(loaderStructName),
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execArg,
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reflect.ValueOf(bkind == kindStruct),
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reflect.ValueOf(obj),
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}
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resp := loadMethod.Func.Call(methodArgs)
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if intf := resp[0].Interface(); intf != nil {
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return errors.Wrapf(intf.(error), "failed to eager load %s", current)
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}
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l.setLoaded(depth)
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} else {
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fmt.Println("!loading", l.toLoad[depth])
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}
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// Check if we can stop
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@ -134,45 +108,165 @@ func (l loadRelationshipState) loadRelationships(depth int, obj interface{}, bki
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return nil
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}
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// *[]*struct -> []*struct
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// *struct -> struct
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loadingFrom = reflect.Indirect(loadingFrom)
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// If it's singular we can just immediately call without looping
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if bkind == kindStruct {
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return l.loadRelationshipsRecurse(depth, loadingFrom)
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}
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// Loop over all eager loaded objects
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ln := loadingFrom.Len()
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if ln == 0 {
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// If we were an empty slice to begin with, bail, probably a useless check
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if loadingFrom.Len() == 0 {
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return nil
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}
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for i := 0; i < ln; i++ {
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iter := reflect.Indirect(loadingFrom.Index(i))
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if err := l.loadRelationshipsRecurse(depth, iter); err != nil {
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return err
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}
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// Collect eagerly loaded things to send into next eager load call
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slice, nextBKind, err := collectLoaded(l.toLoad[depth], loadingFrom)
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if err != nil {
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return err
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}
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// If we could collect nothing we're done
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if slice.Len() == 0 {
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return nil
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}
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ptr := reflect.New(slice.Type())
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ptr.Elem().Set(slice)
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return l.loadRelationships(depth+1, ptr.Interface(), nextBKind)
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}
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// callLoadFunction finds the loader struct, finds the method that we need
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// to call and calls it.
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func (l loadRelationshipState) callLoadFunction(depth int, loadingFrom reflect.Value, typ reflect.Type, bkind bindKind) error {
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current := l.toLoad[depth]
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ln, found := typ.FieldByName(loaderStructName)
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// It's possible a Loaders struct doesn't exist on the struct.
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if !found {
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return errors.Errorf("attempted to load %s but no L struct was found", current)
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}
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// Attempt to find the LoadRelationshipName function
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loadMethod, found := ln.Type.MethodByName(loadMethodPrefix + current)
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if !found {
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return errors.Errorf("could not find %s%s method for eager loading", loadMethodPrefix, current)
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}
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// Hack to allow nil executors
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execArg := reflect.ValueOf(l.exec)
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if !execArg.IsValid() {
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execArg = reflect.ValueOf((*sql.DB)(nil))
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}
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// Get a loader instance from anything we have, *struct, or *[]*struct
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val := reflect.Indirect(loadingFrom)
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if bkind == kindPtrSliceStruct {
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val = reflect.Indirect(val.Index(0))
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}
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methodArgs := []reflect.Value{
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val.FieldByName(loaderStructName),
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execArg,
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reflect.ValueOf(bkind == kindStruct),
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loadingFrom,
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}
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ret := loadMethod.Func.Call(methodArgs)
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if intf := ret[0].Interface(); intf != nil {
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return errors.Wrapf(intf.(error), "failed to eager load %s", current)
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}
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l.setLoaded(depth)
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return nil
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}
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// loadRelationshipsRecurse is a helper function for taking a reflect.Value and
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// Basically calls loadRelationships with: obj.R.EagerLoadedObj, and whether it's a string or slice
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// Basically calls loadRelationships with: obj.R.EagerLoadedObj
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// Called with an obj of *struct
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func (l loadRelationshipState) loadRelationshipsRecurse(depth int, obj reflect.Value) error {
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// Get relationship struct, and if it's good to go, grab the value we just loaded.
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relationshipStruct := obj.FieldByName(relationshipStructName)
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if !relationshipStruct.IsValid() || relationshipStruct.IsNil() {
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return errors.Errorf("could not traverse into loaded %s relationship to load more things", l.toLoad[depth])
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key := l.toLoad[depth]
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r, err := findRelationshipStruct(obj)
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if err != nil {
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return errors.Wrapf(err, "failed to append loaded %s", key)
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}
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loadedObject := reflect.Indirect(relationshipStruct).FieldByName(l.toLoad[depth])
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fmt.Println("loadRecurse", l.toLoad[depth])
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// Pop one off the queue
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depth++
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loadedObject := reflect.Indirect(r).FieldByName(key)
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bkind := kindStruct
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if reflect.Indirect(loadedObject).Kind() != reflect.Struct {
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bkind = kindPtrSliceStruct
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loadedObject = loadedObject.Addr()
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}
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return l.loadRelationships(depth, loadedObject.Interface(), bkind)
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return l.loadRelationships(depth+1, loadedObject.Interface(), bkind)
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}
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// collectLoaded traverses the next level of the graph and picks up all
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// the values that we need for the next eager load query.
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//
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// For example when loadingFrom is [parent1, parent2]
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//
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// parent1 -> child1
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// \-> child2
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// parent2 -> child3
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//
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// This should return [child1, child2, child3]
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func collectLoaded(key string, loadingFrom reflect.Value) (reflect.Value, bindKind, error) {
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// Pull the first one so we can get the types out of it in order to
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// create the proper type of slice.
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current := reflect.Indirect(loadingFrom.Index(0))
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lnFrom := loadingFrom.Len()
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r, err := findRelationshipStruct(current)
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if err != nil {
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return reflect.Value{}, 0, errors.Wrapf(err, "failed to collect loaded %s", key)
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}
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loadedObject := reflect.Indirect(r).FieldByName(key)
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loadedType := loadedObject.Type() // Should be *obj or []*obj
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bkind := kindStruct
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if loadedType.Elem().Kind() != reflect.Struct {
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bkind = kindPtrSliceStruct
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}
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collection := reflect.MakeSlice(loadedType, 0, 0)
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i := 0
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for {
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switch bkind {
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case kindStruct:
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collection = reflect.Append(collection, loadedObject)
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case kindPtrSliceStruct:
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collection = reflect.AppendSlice(collection, loadedObject)
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}
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i++
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if i >= lnFrom {
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break
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}
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current = reflect.Indirect(loadingFrom.Index(i))
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r, err = findRelationshipStruct(current)
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if err != nil {
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return reflect.Value{}, 0, errors.Wrapf(err, "failed to collect loaded %s", key)
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}
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loadedObject = reflect.Indirect(r).FieldByName(key)
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}
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return collection, bkind, nil
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}
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func findRelationshipStruct(obj reflect.Value) (reflect.Value, error) {
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relationshipStruct := obj.FieldByName(relationshipStructName)
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if !relationshipStruct.IsValid() {
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return reflect.Value{}, errors.New("relationship struct was invalid")
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} else if relationshipStruct.IsNil() {
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return reflect.Value{}, errors.New("relationship struct was nil")
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}
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return relationshipStruct, nil
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}
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