diff --git a/.test/event.json b/.test/event.json
new file mode 100644
index 0000000..755b2c7
--- /dev/null
+++ b/.test/event.json
@@ -0,0 +1,28 @@
+{
+  "_group": "system_collections",
+  "_name": "event",
+  "_version": "202507",
+  "singular": "event",
+  "plural": "events",
+  "idPrefix": "e",
+  "indexSpecs": [],
+  "timeseries": {
+    "timeField": "createdAt",
+    "metaField": "name",
+    "granularity": "minutes"
+  },
+  "schema": {
+    "type": "object",
+    "properties": {
+      "_id": {
+        "bsonType": "string"
+      },
+      "name": {
+        "bsonType": "string"
+      },
+      "createdAt": {
+        "bsonType": "timestamp"
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/.test/offer.json b/.test/offer.json
new file mode 100644
index 0000000..4b778e2
--- /dev/null
+++ b/.test/offer.json
@@ -0,0 +1,35 @@
+{
+  "_group": "system_collections",
+  "_name": "offer",
+  "_version": "202507",
+  "singular": "offer",
+  "plural": "offers",
+  "idPrefix": "ofr",
+  "indexSpecs": [{
+    "name": "name_1",
+    "keys": { "name": 1 },
+    "unique": true
+  }],
+  "discriminator": {
+    "field": "store",
+    "ctxField": "store",
+    "collection": "store"
+  },
+  "schema": {
+    "type": "object",
+    "properties": {
+      "_id": {
+        "bsonType": "string"
+      },
+      "name": {
+        "bsonType": "string"
+      },
+      "store": {
+        "bsonType": "string"
+      },
+      "createdAt": {
+        "bsonType": "date"
+      }
+    }
+  }
+}
diff --git a/.test/store.json b/.test/store.json
new file mode 100644
index 0000000..028c9f0
--- /dev/null
+++ b/.test/store.json
@@ -0,0 +1,36 @@
+{
+  "_group": "system_collections",
+  "_name": "store",
+  "_version": "202507",
+  "singular": "store",
+  "plural": "stores",
+  "idPrefix": "str",
+  "indexSpecs": [{
+    "name": "code_1",
+    "keys": { "code": 1 },
+    "unique": true
+  }],
+  "schema": {
+    "type": "object",
+    "properties": {
+      "_id": {
+        "bsonType": "string"
+      },
+      "code": {
+        "bsonType": "string"
+      },
+      "name": {
+        "bsonType": "string"
+      },
+      "created_at": {
+        "bsonType": "date"
+      },
+      "updated_at": {
+        "bsonType": "date"
+      },
+      "archived_at": {
+        "bsonType": "date"
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/discrimination.go b/discrimination.go
new file mode 100644
index 0000000..97d6adc
--- /dev/null
+++ b/discrimination.go
@@ -0,0 +1,47 @@
+package mongo
+
+import (
+	"log"
+	"fmt"
+	"context"
+
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+func (c *MongoClient) DiscriminatorCheckAndApplyToData(ctx context.Context, name string, data map[string]any) error {
+	cdef, ok := c.Registry[name]
+	if ok && cdef.Discriminator != nil {
+		log.Printf("Discriminator found for %s; will use it", name)
+
+		// get from context
+		vAny := ctx.Value(cdef.Discriminator.CtxField)
+		if vAny == nil {
+			return fmt.Errorf("discriminator field required for %s", name)
+		}
+
+		// update payload
+		v := vAny.(string)
+		data[cdef.Discriminator.Field] = v
+	}
+
+	return nil
+}
+
+func (c *MongoClient) DiscriminatorCheckAndApplyToFilter(ctx context.Context, name string, filter bson.M) error {
+	cdef, ok := c.Registry[name]
+	if ok && cdef.Discriminator != nil {
+		log.Printf("Discriminator found for %s; will use it", name)
+
+		// get from context
+		vAny := ctx.Value(cdef.Discriminator.CtxField)
+		if vAny == nil {
+			return fmt.Errorf("discriminator field required for %s", name)
+		}
+
+		// update payload
+		v := vAny.(string)
+		filter[cdef.Discriminator.Field] = bson.M{"$eq": v}
+	}
+
+	return nil
+}
diff --git a/ensure.go b/ensure.go
new file mode 100644
index 0000000..653b0b4
--- /dev/null
+++ b/ensure.go
@@ -0,0 +1,72 @@
+package mongo
+
+import (
+	"time"
+	"fmt"
+
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"github.com/matoous/go-nanoid/v2"
+)
+
+const alphabet = "0123456789abcdefghijclmnopqrstuvwxyz"
+
+const maxLen = 10
+
+// ensureId adds the id property when missing or when it's an empty string.
+func ensureId(data bson.M, idPrefix string) string {
+	maybeId, hasId := data["_id"]
+
+	var id, finalId string
+	if !hasId || maybeId == "" {
+		id, _ = gonanoid.Generate(alphabet, maxLen)
+		if idPrefix != "" {
+			finalId = fmt.Sprintf("%s_%s", idPrefix, id)
+		} else {
+			finalId = id
+		}
+
+		data["_id"] = finalId
+	}
+
+	return finalId
+}
+
+func ensureNoId(data bson.M) {
+	if _, ok := data["_id"]; ok {
+		delete(data, "_id")
+	}
+}
+
+func ensureExistingCreatedAt(data bson.M, old bson.M) time.Time {
+	var cAt time.Time
+	cAtAny, ok := old["createdAt"]
+	if ok {
+		switch cAtAny.(type) {
+		case bson.DateTime:
+			cAtBson := cAtAny.(bson.DateTime)
+			cAt = cAtBson.Time()
+		default:
+			cAt = cAtAny.(time.Time)
+		}
+		
+		data["createdAt"] = cAt
+	}
+
+	return cAt
+}
+
+func ensureCreatedAt(data bson.M) time.Time {
+	now := time.Now().UTC().Truncate(time.Millisecond)
+
+	data["createdAt"] = now
+
+	return now
+}
+
+func ensureUpdatedAt(data bson.M) time.Time {
+	now := time.Now().UTC().Truncate(time.Millisecond)
+
+	data["updatedAt"] = now
+
+	return now
+}
\ No newline at end of file
diff --git a/ensure_test.go b/ensure_test.go
new file mode 100644
index 0000000..c53e0bc
--- /dev/null
+++ b/ensure_test.go
@@ -0,0 +1,90 @@
+package mongo
+
+import (
+	"testing"
+	"time"
+	"testing/synctest"
+
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+func TestEnsureId(t *testing.T) {
+	data := map[string]any {
+		"Name": "My Name Is",
+	}
+
+	ensureId(data, "")
+
+	if id, okid := data["_id"]; !okid || id == "" {
+		t.Fatal("Failed to add Id")
+	}
+}
+
+func TestEnsureId_EmptyId(t *testing.T) {
+	data := map[string]any {
+		"_id": "myidxxxxxx",
+		"name": "My Name Is",
+	}
+
+	ensureId(data, "")
+
+	if data["_id"] == "" {
+		t.Fatal("Id was updated")
+	}
+}
+
+func TestEnsureId_ExistingId(t *testing.T) {
+	data := map[string]any {
+		"_id": "",
+		"name": "My Name Is",
+	}
+
+	ensureId(data, "")
+
+	if id, okid := data["_id"]; !okid || id == "" {
+		t.Fatal("Failed to add Id")
+	}
+}
+
+func TestEnsureCreatedAt(t *testing.T) {
+	data := map[string]any {
+		"name": "My Name Is",
+	}
+
+	synctest.Test(t, func(t *testing.T) {
+		now := ensureCreatedAt(data)
+
+		if createdAt, _ := data["createdAt"]; createdAt != now {
+			t.Fatal("Failed to add CreatedAt")
+		}
+	})
+}
+
+func TestEnsureExistingCreatedAt(t *testing.T) {
+	tm, err := time.Parse(time.RFC3339, "2025-12-24T13:00:11Z")
+	if err != nil { t.Fatal(err) }
+
+	// t.Fatalf("==> %T", tm)
+
+	old := bson.M{"createdAt": tm}
+
+	data := bson.M{}
+
+	ensureExistingCreatedAt(data, old)
+
+	if data["createdAt"] != tm {
+		t.Fatal("wrong date")
+	}
+}
+
+func TestEnsureExistingCreatedAt_NoField(t *testing.T) {
+	old := bson.M{"name": "I have no created at"}
+
+	data := bson.M{}
+
+	ensureExistingCreatedAt(data, old)
+
+	if _, ok := data["createdAt"]; ok {
+		t.Fatal("Should had no createdAt")
+	}
+}
\ No newline at end of file
diff --git a/find.go b/find.go
index 40e03ee..32c76b1 100644
--- a/find.go
+++ b/find.go
@@ -16,6 +16,10 @@ func (c *MongoClient) Find(ctx context.Context, database, name string, filter bs
 
 	sort := bson.M{"_id": 1}
 
+	if err := c.DiscriminatorCheckAndApplyToFilter(ctx, name, filter); err != nil {
+		return nil, err
+	}
+
 	pipeline := BuildPaginationPipeline(0, pageSize + 1, filter, sort)
 
 	// 2. Query
diff --git a/find_test.go b/find_test.go
index d468e36..1223100 100644
--- a/find_test.go
+++ b/find_test.go
@@ -1,10 +1,14 @@
 package mongo
 
 import (
+	"os"
 	"context"
 	"testing"
+	"encoding/json"
 
 	"go.mongodb.org/mongo-driver/v2/bson"
+
+	"git.gsuntres.com/general/commons"
 )
 
 func TestFind_Default(t *testing.T) {
@@ -49,3 +53,69 @@ func TestFind_Default(t *testing.T) {
 		t.Fatalf("Expected total to be 1 but found %d", total)
 	}
 }
+
+func TestFind_Discriminator(t *testing.T) {
+	// 1. Register schemas
+	schemaStore, err := os.ReadFile("./.test/store.json")
+	if err != nil { t.Fatal(err) }
+
+	schemaOffer, err := os.ReadFile("./.test/offer.json")
+	if err != nil { t.Fatal(err) }
+
+	var store bson.M
+	if err := json.Unmarshal(schemaStore, &store); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaStore), schemaStore[:4])
+	}
+
+	var offer bson.M
+	if err := json.Unmarshal(schemaOffer, &offer); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaOffer), schemaOffer[:4])
+	}
+
+	client := GetMongoClient()
+	client.AddDefinition(store)
+	client.AddDefinition(offer)
+
+	// Save two offers with the similar name in different stores each.
+	ctx1 := context.Background()
+	ctx1 = context.WithValue(ctx1, "account", "xxxxxx")
+	ctx1 = context.WithValue(ctx1, "store", "str_1234")
+
+	// One offer in str_1234
+  offer1 := map[string]any { "name": "OSRAM 1" }
+  _, err = client.InsertOne(ctx1, "mydb", "offer", offer1)
+  if err != nil { t.Fatalf("Failed to insertOne %#v", err) }
+
+  // The other in str_4321
+  ctx2 := context.Background()
+	ctx2 = context.WithValue(ctx2, "account", "xxxxxx")
+	ctx2 = context.WithValue(ctx2, "store", "str_4321")
+	offer2 := map[string]any { "name": "OSRAM 2" }
+  _, err = client.InsertOne(ctx2, "mydb", "offer", offer2)
+  if err != nil { t.Fatalf("Failed to insertOne %#v", err) }
+	
+	// Now searching in store str_1234 for OSRAM should return only one
+
+	filter := bson.M{"name": bson.M{"$regex": "OSRAM*"}}
+	findResult, err := client.Find(ctx1, "mydb", "offer", filter, 0)
+	if err != nil { t.Fatalf("Failed to find %#v", err) }
+
+	dataAny, hasData := findResult["data"]
+	if !hasData { t.Fatal("no data") }
+
+	data := dataAny.(bson.A)
+
+	if len(data) != 1 {
+		t.Fatalf("Expected to return 1 document but got %d", len(data))
+	}
+
+	arr, _ := commons.BsonAToSlice(data)
+
+	o := arr[0]
+
+	name := o["name"]
+
+	if name != "OSRAM 1" {
+	 	t.Fatalf("Expected OSRAM 1 not %s", name)
+	}
+}
diff --git a/go.mod b/go.mod
index 7f8e869..7083fad 100644
--- a/go.mod
+++ b/go.mod
@@ -3,14 +3,14 @@ module git.gsuntres.com/general/mongo
 go 1.25.0
 
 require (
-	git.gsuntres.com/general/commons v0.0.0-20260329160148-434ecef67a94
+	git.gsuntres.com/general/commons v0.0.0-20260416141603-7a6c5b6c3c8c
 	git.gsuntres.com/general/sys v0.0.0-20260329160429-49966ca31027
 	github.com/go-viper/mapstructure/v2 v2.5.0
 	github.com/google/go-cmp v0.7.0
 	github.com/matoous/go-nanoid/v2 v2.1.0
 	github.com/testcontainers/testcontainers-go v0.41.0
 	github.com/testcontainers/testcontainers-go/modules/mongodb v0.41.0
-	go.mongodb.org/mongo-driver/v2 v2.5.0
+	go.mongodb.org/mongo-driver/v2 v2.5.1
 )
 
 require (
@@ -69,9 +69,9 @@ require (
 	go.opentelemetry.io/otel/metric v1.41.0 // indirect
 	go.opentelemetry.io/otel/trace v1.41.0 // indirect
 	golang.org/x/crypto v0.48.0 // indirect
-	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/sync v0.20.0 // indirect
 	golang.org/x/sys v0.41.0 // indirect
-	golang.org/x/text v0.34.0 // indirect
+	golang.org/x/text v0.36.0 // indirect
 	google.golang.org/grpc v1.79.1 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
diff --git a/go.sum b/go.sum
index 89a8a51..020a1de 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,7 @@
 dario.cat/mergo v1.0.2 h1:85+piFYR1tMbRrLcDwR18y4UKJ3aH1Tbzi24VRW1TK8=
 dario.cat/mergo v1.0.2/go.mod h1:E/hbnu0NxMFBjpMIE34DRGLWqDy0g5FuKDhCb31ngxA=
-git.gsuntres.com/general/commons v0.0.0-20260329160148-434ecef67a94 h1:U0R2Mg00oC9dWNkXWZMRCBj8Fx6out3HHNIR24srWJ8=
-git.gsuntres.com/general/commons v0.0.0-20260329160148-434ecef67a94/go.mod h1:gVqoj8oD7D81CnU7vWZbv2jbSYXQDtHBcXs4t6E3rWM=
+git.gsuntres.com/general/commons v0.0.0-20260416141603-7a6c5b6c3c8c h1:3jh+CfW0j4JQOa1tRN7UFWcbv5LxBRdHAeM8SoPDbJM=
+git.gsuntres.com/general/commons v0.0.0-20260416141603-7a6c5b6c3c8c/go.mod h1:ZawSPCI/Irjx7P83qJRcknKGuLLJ9c7hhP4OXgILnCY=
 git.gsuntres.com/general/sys v0.0.0-20260329160429-49966ca31027 h1:4pmcjxEDM4rzv+iimQ7wTgCAQ1VnAoeGiHLuf6wC6Fw=
 git.gsuntres.com/general/sys v0.0.0-20260329160429-49966ca31027/go.mod h1:OVs7w4/tJO1GT7cLIeEsb90LuZqH2xYIVQODI5P1GJs=
 github.com/AdaLogics/go-fuzz-headers v0.0.0-20240806141605-e8a1dd7889d6 h1:He8afgbRMd7mFxO99hRNu+6tazq8nFF9lIwo9JFroBk=
@@ -132,8 +132,8 @@ github.com/youmark/pkcs8 v0.0.0-20240726163527-a2c0da244d78/go.mod h1:aL8wCCfTfS
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 github.com/yusufpapurcu/wmi v1.2.4 h1:zFUKzehAFReQwLys1b/iSMl+JQGSCSjtVqQn9bBrPo0=
 github.com/yusufpapurcu/wmi v1.2.4/go.mod h1:SBZ9tNy3G9/m5Oi98Zks0QjeHVDvuK0qfxQmPyzfmi0=
-go.mongodb.org/mongo-driver/v2 v2.5.0 h1:yXUhImUjjAInNcpTcAlPHiT7bIXhshCTL3jVBkF3xaE=
-go.mongodb.org/mongo-driver/v2 v2.5.0/go.mod h1:yOI9kBsufol30iFsl1slpdq1I0eHPzybRWdyYUs8K/0=
+go.mongodb.org/mongo-driver/v2 v2.5.1 h1:j2U/Qp+wvueSpqitLCSZPT/+ZpVc1xzuwdHWwl7d8ro=
+go.mongodb.org/mongo-driver/v2 v2.5.1/go.mod h1:yOI9kBsufol30iFsl1slpdq1I0eHPzybRWdyYUs8K/0=
 go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
 go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.49.0 h1:jq9TW8u3so/bN+JPT166wjOI6/vQPF6Xe7nMNIltagk=
@@ -164,8 +164,8 @@ golang.org/x/net v0.49.0 h1:eeHFmOGUTtaaPSGNmjBKpbng9MulQsJURQUAfUwY++o=
 golang.org/x/net v0.49.0/go.mod h1:/ysNB2EvaqvesRkuLAyjI1ycPZlQHM3q01F02UY/MV8=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
-golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
+golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190916202348-b4ddaad3f8a3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -185,8 +185,8 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
-golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
-golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
+golang.org/x/text v0.36.0 h1:JfKh3XmcRPqZPKevfXVpI1wXPTqbkE5f7JA92a55Yxg=
+golang.org/x/text v0.36.0/go.mod h1:NIdBknypM8iqVmPiuco0Dh6P5Jcdk8lJL0CUebqK164=
 golang.org/x/time v0.0.0-20220210224613-90d013bbcef8 h1:vVKdlvoWBphwdxWKrFZEuM0kGgGLxUOYcY4U/2Vjg44=
 golang.org/x/time v0.0.0-20220210224613-90d013bbcef8/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/insert.go b/insert.go
index fbcec36..8f37740 100644
--- a/insert.go
+++ b/insert.go
@@ -2,18 +2,10 @@ package mongo
 
 import (
 	"context"
-	"time"
-	"fmt"
-
+	
 	"go.mongodb.org/mongo-driver/v2/bson"
-	"github.com/matoous/go-nanoid/v2"
-
-	// "git.gsuntres.com/boxtep/boxtep/core"
 )
 
-const alphabet = "0123456789abcdefghijclmnopqrstuvwxyz"
-
-const maxLen = 10
 
 // InsertOneWithStruct can be used to insert defined structs.
 func (c *MongoClient) InsertOneFromStruct(ctx context.Context, database, name string, data any) (bson.M, error) {
@@ -31,6 +23,10 @@ func (c *MongoClient) InsertOne(ctx context.Context, database, name string, data
 
 	prepareForInsert(data, c.GetIdPrefix(name))
 
+	if err := c.DiscriminatorCheckAndApplyToData(ctx, name, data); err != nil {
+		return nil, err
+	}
+
 	if _, err := collection.InsertOne(ctx, data); err != nil {
 		return nil, err
 	}
@@ -47,37 +43,4 @@ func prepareForInsert(data bson.M, idPrefix string) {
 	ensureUpdatedAt(data)
 }
 
-// ensureId adds the id property when missing or when it's an empty string.
-func ensureId(data bson.M, idPrefix string) string {
-	maybeId, hasId := data["_id"]
 
-	var id, finalId string
-	if !hasId || maybeId == "" {
-		id, _ = gonanoid.Generate(alphabet, maxLen)
-		if idPrefix != "" {
-			finalId = fmt.Sprintf("%s_%s", idPrefix, id)
-		} else {
-			finalId = id
-		}
-
-		data["_id"] = finalId
-	}
-
-	return finalId
-}
-
-func ensureCreatedAt(data bson.M) time.Time {
-	now := time.Now().UTC().Truncate(time.Millisecond)
-
-	data["created_at"] = now
-
-	return now
-}
-
-func ensureUpdatedAt(data bson.M) time.Time {
-	now := time.Now().UTC().Truncate(time.Millisecond)
-
-	data["updated_at"] = now
-
-	return now
-}
diff --git a/insert_test.go b/insert_test.go
index 465fa8f..8440f5e 100644
--- a/insert_test.go
+++ b/insert_test.go
@@ -5,7 +5,6 @@ import (
 	"context"
 	"strings"
 	"testing"
-	"testing/synctest"
 	"encoding/json"
 
 	"go.mongodb.org/mongo-driver/v2/bson"
@@ -122,54 +121,118 @@ func TestPrepareForInsert_ExistingId(t *testing.T) {
 	}
 }
 
-func TestEnsureId(t *testing.T) {
-	data := map[string]any {
-		"Name": "My Name Is",
+func TestInsertOne_Discriminate(t *testing.T) {
+	// 1. Register schemas
+	schemaStore, err := os.ReadFile("./.test/store.json")
+	if err != nil { t.Fatal(err) }
+
+	schemaOffer, err := os.ReadFile("./.test/offer.json")
+	if err != nil { t.Fatal(err) }
+
+	var store bson.M
+	if err := json.Unmarshal(schemaStore, &store); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaStore), schemaStore[:4])
 	}
 
-	ensureId(data, "")
-
-	if id, okid := data["_id"]; !okid || id == "" {
-		t.Fatal("Failed to add Id")
+	var offer bson.M
+	if err := json.Unmarshal(schemaOffer, &offer); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaOffer), schemaOffer[:4])
 	}
+
+	client := GetMongoClient()
+	client.AddDefinition(store)
+	client.AddDefinition(offer)
+
+	// Test
+	ctx := context.Background()
+	ctx = context.WithValue(ctx, "account", "xxxxxx")
+	ctx = context.WithValue(ctx, "store", "str_1234")
+
+	// 2. Insert data
+  offer1 := map[string]any {
+    "name": "Offer 1",
+  }
+
+  saved, err := client.InsertOne(ctx, "mydb", "offer", offer1)
+  if err != nil { t.Fatalf("Failed to insertOne %#v", err) }
+
+  v, ok := saved["store"]
+  if !ok || v != "str_1234" {
+  	t.Fatalf("Should have set store not %s", v)
+  }
 }
 
-func TestEnsureId_EmptyId(t *testing.T) {
-	data := map[string]any {
-		"_id": "myidxxxxxx",
-		"name": "My Name Is",
+func TestInsertOne_Discriminate_NoStore(t *testing.T) {
+	// 1. Register schemas
+	schemaStore, err := os.ReadFile("./.test/store.json")
+	if err != nil { t.Fatal(err) }
+
+	schemaOffer, err := os.ReadFile("./.test/offer.json")
+	if err != nil { t.Fatal(err) }
+
+	var store bson.M
+	if err := json.Unmarshal(schemaStore, &store); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaStore), schemaStore[:4])
 	}
 
-	ensureId(data, "")
-
-	if data["_id"] == "" {
-		t.Fatal("Id was updated")
+	var offer bson.M
+	if err := json.Unmarshal(schemaOffer, &offer); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaOffer), schemaOffer[:4])
 	}
+
+	client := GetMongoClient()
+	client.AddDefinition(store)
+	client.AddDefinition(offer)
+
+	// Test
+	ctx := context.Background()
+
+	// 2. Insert data
+  offer1 := map[string]any {
+    "name": "Offer 1",
+  }
+
+  _, err = client.InsertOne(ctx, "mydb", "offer", offer1)
+  if err == nil {
+  	t.Fatal("Should have required store")
+  }
 }
 
-func TestEnsureId_ExistingId(t *testing.T) {
-	data := map[string]any {
-		"_id": "",
-		"name": "My Name Is",
+func TestInsertOne_Discriminate_EnsureStore(t *testing.T) {
+	// 1. Register schemas
+	schemaStore, err := os.ReadFile("./.test/store.json")
+	if err != nil { t.Fatal(err) }
+
+	schemaOffer, err := os.ReadFile("./.test/offer.json")
+	if err != nil { t.Fatal(err) }
+
+	var store bson.M
+	if err := json.Unmarshal(schemaStore, &store); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaStore), schemaStore[:4])
 	}
 
-	ensureId(data, "")
-
-	if id, okid := data["_id"]; !okid || id == "" {
-		t.Fatal("Failed to add Id")
-	}
-}
-
-func TestEnsureCreatedAt(t *testing.T) {
-	data := map[string]any {
-		"name": "My Name Is",
+	var offer bson.M
+	if err := json.Unmarshal(schemaOffer, &offer); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaOffer), schemaOffer[:4])
 	}
 
-	synctest.Test(t, func(t *testing.T) {
-		now := ensureCreatedAt(data)
+	client := GetMongoClient()
+	client.AddDefinition(store)
+	client.AddDefinition(offer)
 
-		if createdAt, _ := data["created_at"]; createdAt != now {
-			t.Fatal("Failed to add CreatedAt")
-		}
-	})
-}
+	// Test
+	ctx := context.Background()
+	ctx = context.WithValue(ctx, "store", "str_1234")
+
+	// 2. Insert data
+  offer1 := map[string]any {
+    "name": "Offer 100",
+    "store": "str_0000",
+  }
+
+  saved, err := client.InsertOne(ctx, "mydb", "offer", offer1)
+  
+  if saved["store"] != "str_1234" {
+  	t.Fatal("Wrong store")
+  }
+}
\ No newline at end of file
diff --git a/main.go b/main.go
index 50cca1f..76e2f17 100644
--- a/main.go
+++ b/main.go
@@ -19,6 +19,10 @@ import (
 	"git.gsuntres.com/general/sys"
 )
 
+func main() {
+	log.SetFlags(log.LstdFlags | log.Lshortfile)
+}
+
 // WithiSessionFunc will run operations on the database within the same session.
 // If this functions returns an error, the system will rollback the transaction.
 // Sessions require a resplica set.
@@ -38,14 +42,29 @@ type IMongoClient interface {
 	GetCollection(database, name string) *mongo.Collection
 }
 
+type Timeseries struct {
+	TimeField   string `bson:"timeField"`
+	MetaField   string `bson:"metaField"`
+	Granularity string `bson:"granularity"`
+}
+
+type Discriminator struct {
+	Field         string `bson:"field"`
+	CtxField      string `bson:"ctxField"`
+	Collection    string `bson:"collection"`
+	Required      bool   `bson:"required,omitempty"`
+}
+
 type CollectionDefinition struct {
-	Name       string `bson:"_name"`
-	Singular   string `bson:"singular"`
-	Plural     string `bson:"plural"`
-	IdPrefix   string `bson:"idPrefix"`
-	IndexSpecs []map[string]any `bson:"indexSpecs"`
-	Schema     map[string]any `bson:"schema"`
-	Views 	   map[string]any `bson:"views"`
+	Name          string `bson:"_name"`
+	Singular      string `bson:"singular"`
+	Plural        string `bson:"plural"`
+	IdPrefix      string `bson:"idPrefix"`
+	IndexSpecs    []map[string]any `bson:"indexSpecs"`
+	Schema        map[string]any `bson:"schema"`
+	Views 	      map[string]any `bson:"views"`
+	Timeseries    *Timeseries `bson:"timeseries,omitempty"`
+	Discriminator *Discriminator
 }
 
 // func (cd *CollectionDefinition) GetSchema(name string)
@@ -75,34 +94,6 @@ func (c *MongoClient) GetIdPrefix(name string) string {
 	return ""
 }
 
-const ADD_DEFINITION_SCHEMA = `
-{
-	"type": "object",
-	"properties": {
-		"_name": {
-			"type": "string"
-		},
-		"idPrefix": {
-			"type": "string"
-		},
-		"indexSpecs": {
-			"type": "array"
-		},
-		"singular": {
-			"type": "string"
-		},
-		"system": {
-			"type": "boolean"
-		},
-		"plural": {
-			"type": "string"
-		}
-	},
-	"required": ["_name", "singular", "plural"],
-	"additionalProperties": true
-}
-`
-
 func (c *MongoClient) AddDefinition(data map[string]any) {
 	if valid := commons.Validate(ADD_DEFINITION_SCHEMA, data); valid != nil {
 		log.Printf("failed to register data: %v", valid)
@@ -154,6 +145,7 @@ func (c *MongoClient) GetCollection(database, name string) *mongo.Collection {
 		if ok {
 			log.Printf("Schema found for %s; will use it", name)
 
+			ApplyTimeSeries(cdef, opts)
 			ApplySchema(cdef, opts)
 		} else {
 			log.Printf("No schema for %s", name)
@@ -168,16 +160,28 @@ func (c *MongoClient) GetCollection(database, name string) *mongo.Collection {
 		collection := db.Collection(name)
 
 		c.CreateIndexes(collection, cdef)
-
 		c.CreateViews(db, cdef)
 
 		return collection
 	}
 }
 
+func ApplyTimeSeries(cdef *CollectionDefinition, opts *options.CreateCollectionOptionsBuilder) {
+	if cdef.Timeseries != nil {
+		tsOpts := options.TimeSeries().
+			SetTimeField(cdef.Timeseries.TimeField).
+			SetMetaField(cdef.Timeseries.MetaField).
+			SetGranularity(cdef.Timeseries.Granularity)
+
+		opts.SetTimeSeriesOptions(tsOpts)
+	} else {
+		log.Printf("No timeseries")
+	}
+}
+
 func ApplySchema(cdef *CollectionDefinition, opts *options.CreateCollectionOptionsBuilder) {
 	// Add schema validation
-	if cdef.Schema != nil {
+	if cdef.Schema != nil && cdef.Timeseries == nil {
 		schemaBson, err := bson.Marshal(cdef.Schema)
 		if err != nil {
 			log.Printf("failed to parse schema: %v", err)
@@ -191,7 +195,7 @@ func ApplySchema(cdef *CollectionDefinition, opts *options.CreateCollectionOptio
 			opts.SetValidator(validator)
 		}
 	} else {
-		log.Printf("Invalid schema, do nothing.")
+		log.Printf("Validation disabled")
 	}
 }
 
@@ -353,3 +357,70 @@ func MapToBsonD(m map[string]any) (bson.D, error) {
 
     return d, nil
 }
+
+const ADD_DEFINITION_SCHEMA = `
+{
+	"type": "object",
+	"properties": {
+		"_name": {
+			"type": "string"
+		},
+		"idPrefix": {
+			"type": "string"
+		},
+		"indexSpecs": {
+			"type": "array"
+		},
+		"singular": {
+			"type": "string"
+		},
+		"system": {
+			"type": "boolean"
+		},
+		"plural": {
+			"type": "string"
+		},
+		"schema": {
+			"type": "object"
+		},
+		"views": {
+			"type": "object"
+		},
+		"timeseries": {
+			"type": "object",
+			"properties": {
+				"timeField": {
+					"type": "string"
+				},
+				"metaField": {
+					"type": "string"
+				},
+				"granularity": {
+					"enum": [ "seconds", "minutes", "hours"]
+				}
+			},
+			"required": ["timeField", "metaField", "granularity"]
+		},
+		"discriminator": {
+			"type": "object",
+			"properties": {
+				"field": {
+					"type": "string"
+				},
+				"ctxField": {
+					"type": "string"
+				},
+				"collection": {
+	        		"type": "string"
+	        	},
+	        	"required": {
+	        		"type": "boolean"
+	        	}
+			},
+			"required": ["field", "ctxField", "collection"]
+        }
+	},
+	"required": ["_name", "singular", "plural"],
+	"additionalProperties": true
+}
+`
\ No newline at end of file
diff --git a/main_index_test.go b/main_index_test.go
index d9a1f07..b87d416 100644
--- a/main_index_test.go
+++ b/main_index_test.go
@@ -1,9 +1,12 @@
 package mongo
 
 import (
+  "fmt"
+  "os"
   "context"
   "testing"
   "time"
+  "encoding/json"
 
   "go.mongodb.org/mongo-driver/v2/bson"
 )
@@ -54,3 +57,59 @@ func TestCreateIndexes(t *testing.T) {
       t.Fatal("Should have register index idx_1")
   }
 }
+
+func TestCreateTimeSeries(t *testing.T) {
+  // 1. Register schemas
+  schemaEvent, err := os.ReadFile("./.test/event.json")
+  if err != nil { t.Fatal(err) }
+
+  var event bson.M
+  if err := json.Unmarshal(schemaEvent, &event); err != nil {
+    t.Fatalf("Length: %d, First bytes: %x\n", len(schemaEvent), schemaEvent[:4])
+  }
+
+  client := GetMongoClient()
+  client.AddDefinition(event)
+
+  // 2. Insert data
+  event1 := map[string]any {
+    "name": "event1",
+    "createdAt": time.Now(),
+  }
+
+  _, err = client.InsertOne(context.Background(), "mydb", "event", event1)
+  if err != nil { t.Fatalf("Failed to insertOne %#v", err) }
+
+  c := client.GetCollection("mydb", "event")
+  db := c.Database()
+
+  cmd := bson.D{
+    {Key: "listCollections", Value: 1},
+    {Key: "filter", Value: bson.D{
+      {Key: "name", Value: "event"},
+    }},
+  }
+
+  var result struct {
+    Cursor struct {
+      FirstBatch []bson.M `bson:"firstBatch"`
+    } `bson:"cursor"`
+  }
+  err = db.RunCommand(context.Background(), cmd).Decode(&result)
+  if err != nil {
+      t.Fatal(err)
+  }
+
+  coll := result.Cursor.FirstBatch[0]
+
+  if coll["type"] != "timeseries" {
+    fmt.Println("❌ time series collection")
+  }
+
+  if opts, ok := coll["options"].(bson.M); ok {
+    if _, ok := opts["timeseries"]; !ok {
+      t.Fatal("❌ time series collection")
+    }
+  }
+
+}
\ No newline at end of file
diff --git a/main_test.go b/main_test.go
index 4ce6dc1..2a8e0cc 100644
--- a/main_test.go
+++ b/main_test.go
@@ -51,6 +51,7 @@ func TestMain(m *testing.M) {
     MongoUri: endpoint,
     MongoUser: user,
     MongoPass: pass,
+    MongoDebugQuery: false,
   })
 
   // 3. Run tests
diff --git a/main_views.go b/main_views.go
index 85dd03e..fde7356 100644
--- a/main_views.go
+++ b/main_views.go
@@ -14,7 +14,7 @@ import (
 // CreateViews will create views for the given collection and definition.
 func (c *MongoClient) CreateViews(db *mongo.Database, cdef *CollectionDefinition) {
   if cdef == nil || cdef.Views == nil {
-    log.Printf("No definitions will not create views")
+    log.Printf("No definition for views found.")
 
     return
   }
diff --git a/replace.go b/replace.go
new file mode 100644
index 0000000..fdd305d
--- /dev/null
+++ b/replace.go
@@ -0,0 +1,47 @@
+package mongo
+
+import (
+	"context"
+	
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.mongodb.org/mongo-driver/v2/mongo"
+)
+
+func (c *MongoClient) Replace(ctx context.Context, database, name string, id string, data bson.M) (bson.M, error) {
+	collection := c.GetCollection(database, name)
+
+	filter := map[string]any { "_id": id }
+
+	var found bson.M
+	err := collection.FindOne(ctx, filter).Decode(&found)
+	if err != nil {
+		return nil, err
+	}
+
+	prepareForReplace(data, found)
+
+	if err := c.DiscriminatorCheckAndApplyToData(ctx, name, data); err != nil {
+		return  nil, err
+	}
+
+	updateResult, err := collection.ReplaceOne(ctx, filter, data)
+	if err != nil {
+		return nil, err
+	}
+
+	PostReplace(updateResult, data, id)
+
+	return data, nil
+}
+
+func PostReplace(updateResult *mongo.UpdateResult, data bson.M, id string) {
+	if updateResult.ModifiedCount == 1 {
+		data["_id"] = id
+	}
+}
+
+func prepareForReplace(data bson.M, old bson.M) {
+	ensureNoId(data)
+	ensureUpdatedAt(data)
+	ensureExistingCreatedAt(data, old)
+}
diff --git a/replace_test.go b/replace_test.go
new file mode 100644
index 0000000..ac65794
--- /dev/null
+++ b/replace_test.go
@@ -0,0 +1,181 @@
+package mongo
+
+import (
+	"os"
+	"context"
+	"testing"
+	"encoding/json"
+
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+func TestReplace(t *testing.T) {
+	data := map[string]any {
+		"_id": "su_2b3c00",
+		"name": "Ava Thompson",
+		"age": int32(26),
+	}
+
+	ctx := context.Background()
+
+	o, err := client.InsertOne(ctx, "mydb", "mycollection", data)
+	if err != nil {	t.Fatalf("Failed to insertOne %#v", err) }
+
+	id := o["_id"].(string)
+
+	// first we retrieve the entity
+	fetched, err := client.GetOne(ctx, "mydb", "mycollection", id)
+	if err != nil {	t.Fatalf("Failed to fetch %#v", err) }
+	
+	fetched["name"] = "Noah Patel"
+
+	replaced, err := client.Replace(ctx, "mydb", "mycollection", id, fetched)
+	if err != nil {	t.Fatalf("Failed to replace %#v", err) }
+
+	// t.Fatalf("-> %v", replaced)
+	if replaced["_id"] != fetched["_id"] {
+		t.Fatalf("Not the same entity")
+	}
+
+	if replaced["name"] != "Noah Patel" {
+		t.Fatal("unexpected name")
+	}
+}
+
+// Make sure discrimination field is used when replacing.
+func TestReplace_Discrimination(t *testing.T) {
+	// 1. Register schemas
+	schemaStore, err := os.ReadFile("./.test/store.json")
+	if err != nil { t.Fatal(err) }
+
+	schemaOffer, err := os.ReadFile("./.test/offer.json")
+	if err != nil { t.Fatal(err) }
+
+	var store bson.M
+	if err := json.Unmarshal(schemaStore, &store); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaStore), schemaStore[:4])
+	}
+
+	var offer bson.M
+	if err := json.Unmarshal(schemaOffer, &offer); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaOffer), schemaOffer[:4])
+	}
+
+	client := GetMongoClient()
+	client.AddDefinition(store)
+	client.AddDefinition(offer)
+
+	// Save data
+	ctx1 := context.Background()
+	ctx1 = context.WithValue(ctx1, "account", "xxxxxx")
+	ctx1 = context.WithValue(ctx1, "store", "str_1234")
+
+	// Save offer
+  offer1 := map[string]any { "name": "OSRAM 10" }
+  saved, err := client.InsertOne(ctx1, "mydb", "offer", offer1)
+  if err != nil { t.Fatalf("Failed to insertOne %#v", err) }
+
+  id := saved["_id"].(string)
+
+  // // Now replace it
+  saved["name"] = "** OSRAM 10 CHANGED **"
+	replaced, err := client.Replace(ctx1, "mydb", "offer", id, saved)
+	if err != nil { t.Fatalf("Failed to replace %#v", err) }
+
+	if replaced["name"] != "** OSRAM 10 CHANGED **" {
+		t.Fatal("Unexpected replaced object")
+	}
+
+	found, err := client.GetOne(ctx1, "mydb", "offer", id)
+	if err != nil { t.Fatalf("Failed to find %#v", err) }
+	
+	if found["name"] != "** OSRAM 10 CHANGED **" {
+		t.Fatal("Updates did not persist")
+	}
+}
+
+func TestReplace_Discrimination_NoStore(t *testing.T) {
+	// 1. Register schemas
+	schemaStore, err := os.ReadFile("./.test/store.json")
+	if err != nil { t.Fatal(err) }
+
+	schemaOffer, err := os.ReadFile("./.test/offer.json")
+	if err != nil { t.Fatal(err) }
+
+	var store bson.M
+	if err := json.Unmarshal(schemaStore, &store); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaStore), schemaStore[:4])
+	}
+
+	var offer bson.M
+	if err := json.Unmarshal(schemaOffer, &offer); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaOffer), schemaOffer[:4])
+	}
+
+	client := GetMongoClient()
+	client.AddDefinition(store)
+	client.AddDefinition(offer)
+
+	// Save data
+	ctx1 := context.Background()
+	ctx1 = context.WithValue(ctx1, "store", "str_1234")
+	
+	// Save offer
+  offer1 := map[string]any { "name": "OSRAM 11" }
+  saved, err := client.InsertOne(ctx1, "mydb", "offer", offer1)
+  if err != nil { t.Fatalf("Failed to insertOne %#v", err) }
+
+  id := saved["_id"].(string)
+
+  // // Now replace it
+  saved["name"] = "** OSRAM 11 CHANGED **"
+	_, err = client.Replace(context.Background(), "mydb", "offer", id, saved)
+	if err == nil { 
+		t.Fatal("should have required store") 
+	}
+
+}
+
+// Should save the right store regardless of the input
+func TestReplace_Discrimination_EnsureStore(t *testing.T) {
+	// 1. Register schemas
+	schemaStore, err := os.ReadFile("./.test/store.json")
+	if err != nil { t.Fatal(err) }
+
+	schemaOffer, err := os.ReadFile("./.test/offer.json")
+	if err != nil { t.Fatal(err) }
+
+	var store bson.M
+	if err := json.Unmarshal(schemaStore, &store); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaStore), schemaStore[:4])
+	}
+
+	var offer bson.M
+	if err := json.Unmarshal(schemaOffer, &offer); err != nil {
+		t.Fatalf("Length: %d, First bytes: %x\n", len(schemaOffer), schemaOffer[:4])
+	}
+
+	client := GetMongoClient()
+	client.AddDefinition(store)
+	client.AddDefinition(offer)
+
+	// Save data
+	ctx1 := context.Background()
+	ctx1 = context.WithValue(ctx1, "store", "str_1234")
+	
+	// Save offer
+  offer1 := map[string]any { "name": "OSRAM 12" }
+  saved, err := client.InsertOne(ctx1, "mydb", "offer", offer1)
+  if err != nil { t.Fatalf("Failed to insertOne %#v", err) }
+
+  id := saved["_id"].(string)
+
+  // // Now replace it
+  saved["store"] = "str_0000"
+	changed, err := client.Replace(ctx1, "mydb", "offer", id, saved)
+	if err != nil { t.Fatalf("Failed to replace %v", err) }
+	if changed["store"] != "str_1234" { 
+		t.Fatal("Should have ensured store") 
+	}
+
+}
\ No newline at end of file