Delete constraint

MichelDiz · July 28, 2019, 5:02pm

You open a transaction, do a query, do your checks in the application side and then use the same transaction to do a mutation based on your checks.

Dgraph never checks anything about that. Unless of course if you use upsert procedure.

BTW Soon you gonna be able to do it in a single operation, using upsert block.

github.com/dgraph-io/dgraph

Support a new Upsert operation

opened 08:21PM - 22 Feb 19 UTC

closed 04:13PM - 08 Aug 19 UTC

manishrjain

kind/feature

This operation would allow a user to run a query, and use its results (via varia…bles) to execute the mutation. This would then allow upserts to happen, without doing multiple network calls to the DB. ``` txn { query { me(func: eq(email, "someone@gmail.com")) { v as uid } } mutation @if(eq(len(v), 0)) { set { <uid(v)> <name> "Some One" . <uid(v)> <email> "someone@gmail.com" . } } } ``` This txn would check for an account with `email=someone@gmail.com`, and only if it is present, would it run the mutation. This should return the result of query, normally. And also return the result of the mutation. Additionally, we should be able to optionally do the mutation, iff the email is already present. ``` txn { query { me(func: eq(email, "someone@gmail.com")) { v as uid } } mutation @if(gt(len(v), 0)) { set { <uid(v)> <name> "Changed Name" . } } } ``` This would introduce a new txn operator, and a new if directive applicable for mutations.

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Delete constraint

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