Understanding FirebaseFirestore Read Data example

Question

On the Read Data example of Firestore this link I don't understand why it is necessary to include de snapshot.hasData to prove that the document does not exist.

if (snapshot.hasData && !snapshot.data!.exists) {
          return Text("Document does not exist");
        }

In addition to Victor's excellent answer, I recommend checking out this answer on the different types of snapshots you may encounter: https://stackoverflow.com/questions/65874202/what-is-the-difference-between-existing-types-of-snapshots-in-firebase/65874916#65874916 — Frank van Puffelen, Sep 13 '21 at 13:54

Victor Eronmosele · Accepted Answer · 2021-09-13T13:47:16.900

4

.hasData is an AsyncSnapshot property that "returns whether [a] snapshot contains a non-null data value."
.exists is a DocumentSnapshot property that "returns true if the document exists."

So .hasData is called to be sure the DocumentSnapshot from Firestore is available (a DocumentSnapshot is returned whether or not the document exists) and .exists is called to figure out if the document does exists.

edited Sep 13 '21 at 13:47

answered Sep 13 '21 at 13:40

Victor Eronmosele

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Understanding FirebaseFirestore Read Data example

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