# Dfx call serialize principal

**URL:** <https://forum.dfinity.org/t/dfx-call-serialize-principal/15347>\
**Category:** Command Line Tools\
**Created:** [September 9, 2022, 10:07am UTC](https://forum.dfinity.org/t/dfx-call-serialize-principal/15347 "2022-09-09T10:07:27Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![peterparker](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@peterparker](https://forum.dfinity.org/u/peterparker)\
**Post date:** [September 9, 2022, 10:07am UTC](https://forum.dfinity.org/t/dfx-call-serialize-principal/15347/1 "2022-09-09T10:07:27Z")

</div>

How do you provide a `Principal` to `dfx` for a call?

e.g.

```auto
dfx canister call rrkah-fqaaa-aaaaa-aaaaq-cai knownBucket '("qaa6y-5yaaa-aaaaa-aaafa-cai")'

```

for given Motoko function:

```auto
public shared func knownBucket(bucketId: Principal) : async (Bool) {

```

ends in a serialization error:

> Error: Failed to create argument blob.  
> Caused by: Failed to create argument blob.  
> Invalid data: Unable to serialize Candid values: type mismatch: “qaa6y-5yaaa-aaaaa-aaafa-cai” cannot be of type principal

Absolutely makes sense and of course, I will modify my function to use a text argument but, curious to know if possible.

---

<div class="post-metadata">

**Author:** ![Vivienne](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/vivienne/32/29170_2.png) [@Vivienne](https://forum.dfinity.org/u/Vivienne)\
**Post date:** [September 9, 2022, 11:09am UTC](https://forum.dfinity.org/t/dfx-call-serialize-principal/15347/2 "2022-09-09T11:09:16Z")

</div>

It looks like this ([Source](https://internetcomputer.org/docs/current/references/candid-ref#type-principal), see “Textual syntax”):

```auto
dfx canister call rrkah-fqaaa-aaaaa-aaaaq-cai knownBucket '(principal "qaa6y-5yaaa-aaaaa-aaafa-cai")'

```

---

<div class="post-metadata">

**Author:** ![peterparker](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@peterparker](https://forum.dfinity.org/u/peterparker)\
**Post date:** [September 9, 2022, 11:23am UTC](https://forum.dfinity.org/t/dfx-call-serialize-principal/15347/3 "2022-09-09T11:23:21Z")

</div>

Thanks @Vivienne - awesome 🤙