# Entities and attributes aliasing feature looks broken

**URL:** <https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287>\
**Category:** Datomic Pro\
**Created:** [December 13, 2019, 6:39pm UTC](https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287 "2019-12-13T18:39:50Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![apopelo](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/apopelo/32/313_2.png) [@apopelo](https://forum.datomic.com/u/apopelo)\
**Post date:** [December 13, 2019, 6:39pm UTC](https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287/1 "2019-12-13T18:39:50Z")

</div>

I have tried to use datomic alias feature both for entities and attributes by using function **db/add** and I got strange behaviour. First case when I’m trying to set aliasing for entities:  
E.g. the next schema is transacted:  
(def user-schema [  
{  
:db/ident :user/code  
:db/valueType :db.type/string  
:db/cardinality :db.cardinality/one  
:db/unique :db.unique/value

```
                   }
                   {
                       :db/ident :user/firstName
                       :db/valueType :db.type/string
                       :db/cardinality :db.cardinality/one
                   }
                   {
                       :db/ident :user/lastName
                       :db/valueType :db.type/string
                       :db/cardinality :db.cardinality/one
                   }

                   ])
(d/transact conn user-schema)

```

Then I’m creating entity:  
(def user-data [  
{  
:db/ident :user/fistLastNames  
:user/firstName “FirstName”  
:user/lastName “LastName”  
:user/code “code1”  
}

```
                   ])
(d/transact conn user-data)

```

Then I’m setting an alias  
(d/transact  
conn  
[[:db/add :user/fistLastNames :db/ident :person/fistLastNames]  
])

If to check entity using both idents it points to the same entity

 ![3](https://us1.discourse-cdn.com/flex016/uploads/cognitect/original/1X/5e2376b668d45895c4fe55fb015794b0e2dae982.jpeg)  
Which ID is 17592186045427, so everything looks, aliasing works well, but once I’m trying to update entity  
(def user-data [  
{  
:db/ident :user/fistLastNames  
:user/lastName “LastNameFixed”  
:user/code “code1”  
}

```
                   ])
(d/transact conn user-data)

```

I’m getting: “Unique conflict: :user/code, value: code1 already held by: 17592186045427 asserted for: 17592186045430”

Actually I’m interested in doing such operations for attributes too, and everything is good even when updating already aliased attribute but using original ident, but the same actions do not work if an updated attribute is part of other attribute(mentioned in :db/tupleAttrs). I’m getting:  
`:db.error/cannot-retarget-ident Ident :user/firstName cannot be used for entity 95, already used for :person/firstName"`

I tried the next schema:

```
(def user-schema [
                   {
                       :db/ident :user/firstName
                       :db/valueType :db.type/string
                       :db/cardinality :db.cardinality/one
                   }
                   {
                       :db/ident :user/lastName
                       :db/valueType :db.type/string
                       :db/cardinality :db.cardinality/one
                   }
                   {
                       :db/ident :user/fullName
                       :db/valueType :db.type/tuple
                       :db/tupleAttrs [:user/firstName :user/lastName]
                       :db/cardinality :db.cardinality/one
                   }

                           ])
(d/transact conn user-schema)

```

Then I did:  
(d/transact  
conn  
[[:db/add :user/firstName :db/ident :person/firstName]  
[:db/add :user/lastName :db/ident :person/lastName]  
[:db/add :user/fullName :db/ident :person/fullName]  
])

So, when I’m trying to transact:  
(def alter-user-schema [  
{  
:db/ident :user/firstName  
:db/valueType :db.type/string  
:db/cardinality :db.cardinality/one  
}

```
                           ])
(d/transact conn alter-user-schema)

```

Then I’m getting the above mentioned error, but when attribute is not part of other tuple attribute then all is good

---

<div class="post-metadata">

**Author:** ![marshall](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/marshall/32/48_2.png) [@marshall](https://forum.datomic.com/u/marshall)\
**Post date:** [December 16, 2019, 2:55pm UTC](https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287/2 "2019-12-16T14:55:21Z")

</div>

I believe you want to be using `:db.unique/identity` for your `:user/code`, not `:db.unique/value`.  
See [https://docs.datomic.com/on-prem/identity.html#unique-identities](https://docs.datomic.com/on-prem/identity.html#unique-identities)

Identity provides the ‘upsert’ functionality you appear to be wanting.

---

<div class="post-metadata">

**Author:** ![apopelo](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/apopelo/32/313_2.png) [@apopelo](https://forum.datomic.com/u/apopelo)\
**Post date:** [December 17, 2019, 7:44am UTC](https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287/3 "2019-12-17T07:44:19Z")

</div>

Yea, it solves issue with entities, I just thought if I use `:db/ident` which unique is `:db.unique/identity` then datomic can resolve references, but okay for entities, what about attributes? I noticed another strange issue related to attribute aliasing in addition to issues for tuple attributes mentioned in the topic:

E.g. I have attribute:

```
{
    :db/ident :product/code
    :db/valueType :db.type/string
    :db/cardinality :db.cardinality/one
}

```

When alias is created

```
(d/transact conn [[:db/add :product/code :db/ident :product/sku]])

```

Both idents point to the same attribute what is correct, but once I’m transacting attribute again:

```
(def attr-schema [
   {
       :db/ident :product/code
       :db/valueType :db.type/string
       :db/cardinality :db.cardinality/one
   }
])
(d/transact conn attr-schema)

```

then datomic creates new attribute instead of executing transaction for previously created attribute.

---

<div class="post-metadata">

**Author:** ![apopelo](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/apopelo/32/313_2.png) [@apopelo](https://forum.datomic.com/u/apopelo)\
**Post date:** [February 5, 2020, 8:52pm UTC](https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287/4 "2020-02-05T20:52:55Z")

</div>

@marshall I’m really interesting on getting your thoughts on this issue, current workaround is to pass db id of attribute then datomic does not create new attribute if existing one is already aliased

```
(def attr-schema [
   {
       :db/id 71 # Passing of ID fixes issue for attributes already aliased
       :db/ident :product/code
       :db/valueType :db.type/string
       :db/cardinality :db.cardinality/one
   }
])
(d/transact conn attr-schema)
```

---

<div class="post-metadata">

**Author:** ![marshall](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/marshall/32/48_2.png) [@marshall](https://forum.datomic.com/u/marshall)\
**Post date:** [February 6, 2020, 1:57pm UTC](https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287/5 "2020-02-06T13:57:19Z")

</div>

I don’t understand why you are re-transacting your attribute definition in the first place.  
Are you attempting to alter the schema?

---

<div class="post-metadata">

**Author:** ![apopelo](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.datomic.com/apopelo/32/313_2.png) [@apopelo](https://forum.datomic.com/u/apopelo)\
**Post date:** [February 6, 2020, 7:06pm UTC](https://forum.datomic.com/t/entities-and-attributes-aliasing-feature-looks-broken/1287/7 "2020-02-06T19:06:41Z")

</div>

As a possible case. I have schema definition represented in JSON format, and each time when my application starts JSON schema is converted to EDN and transacted to datomic, so it’s possible to transact the same attribute structure.