firebase – Is it possible to query Field and retrieve fields and subcollection in the Cloud Firestore?

I have to query fields and retrieve all subcollections and fields. Is it possible?

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      Stream> getChatField(String uid) {
        var ref = _db.collection('chats')
             .where('toUserId', isEqualTo: uid);
//Afterthat need to get sub collection and fields value. is it possible?

        return ref.snapshots().map((list) => list.documents
            .map((doc) => ChatFieldModel.fromForestore(doc))

abstract algebra – basic discriminant and square number field

To let $ a, b in Bbb Z, tau in Bbb Q ( sqrt () {- d}) $ from where $ -D $ is a basic discriminant.

To let $ N: = norm (aτ + b) $ from where $ aτ + b $ is an algebraic integer, so that $ (aτ + b) / m $ is not an algebraic integer for anybody $ m in Bbb Z _ {> 1} $

Prove that $ d le N $ if $ -D not ≡ 1 (mod 4) $ and $ d le 4N $ Otherwise.

I know that $ disc (Q ( sqrt () {- d})) = -d $ if $ -D ≡ 1 (mod 4) $ and the $ disc (Q ( sqrt () {- d})) = -4d $ if $ -D not ≡ 1 (mod 4) $ and that there is a discrepancy between integer quadratic forms and square number fields, but I do not understand how.

Thank you for your help

Ag.algebraische Geometrie – Definition field for general font surfaces

In the survey

from Bauer-Catanese-Pignatelli mention a question from Mumford:

Can a computer classify all surfaces of the general type? $ p_g = 0 $?

I played a bit with the surface of Craighero-Gattazzo (CG) (a
certain surface of this type) using various computer algebra
Systems, and my life was complicated by the fact that
Standard equations for this area are defined by a cubic extension
from $ mathbb {Q} $ rather than over $ mathbb {Q} $ self
Run calculations longer and not use different algorithms
) Reacted.

That worried me about Mumford's question: Because
$ bar { mathbb {Q}} $ is only countable, a generic complex surface in
This module space is only defined by a certain transcendental
Extension of $ mathbb {Q} $, which probably makes Groebner the base
Calculations even less understandable. My question is:

Everything is known in the module space of general surfaces
the existence or density of surfaces over defined $ mathbb {Q} $ or
$ bar { mathbb {Q}} $? Should I be able to disrupt the pluricanonical
Ring the CG surface and find a "near" defined surface over
$ mathbb {Q} $? Should each component of the module space contain an area defined above it $ bar { mathbb {Q}} $?

If this question is too general, I would be glad to know the answer
to the next more specific question.

The CG surface has one
Explicit birational model as a quintet in $ mathbb {P} ^ 3 $ with four
simple elliptic singularities. The standard model is defined via
$ mathbb {Q} (r) / (r ^ 3 + r ^ 2-1) $, It is known that it is necessary to work
above this cubic extension or could there be a similar quintessence defined
over $ mathbb {Q} $ with the required properties, i. whose minimal
Resolution is biholomorphic to (or at least deformation equivalent to)
the CG surface?

Plugins – Edit existing shortcodes in a custom field

I have a very similar question: Custom Fields Bulk Editing

I want to edit ALL data in a custom field, but instead of replacing values, I want to add an attribute to the custom field on each page. Example:

This is an existing speed dial
[idx-listings linkid="387056" count="6"]
I'd like to add an attribute that looks like this:
[idx-listings linkid="387056" count="6" showlargerphotos="true"]
Is there a way to depend on the crowd? showlargerphotos Attribute within the existing shortcode without affecting the rest of the string?

dnd 5e – Can detect magic detects an antimagic field

Recognize magic (PHB, 231) works as follows:

For a long time, feel the presence of magic within 30 feet of you. If you feel magic in this way, your action will allow you to see a faint aura around a visible creature or object in the area where magic reigns, and you may learn their magical school.

The spell can penetrate most barriers, but is blocked by 1 foot of stone, 1 inch of base metal, a thin sheet of lead or 3 feet of wood or dirt.

So we have a character casting Discover magic within the reach of the assistant. Magic within reach should be felt, according to which the character could Use an action to see a faint aura over the wizard and learn the school of magic.

But then the rules around the antimagic field (PHB, 213) come into play.

Spells and other magical effects, except those created by an artifact or deity, are suppressed in the sphere and can not protrude into it.

Areas of magic, The area of ​​another spell or magical effect, eg. B. a fireball, can not reach into the ball. When the sphere overlaps a magic region, the part of the region covered by the sphere is suppressed. For example, the flames created by a fire wall in the ball are suppressed, creating a gap in the wall when the overlap is large enough

Magic. An active spell or magical effect on a creature or object in the sphere is suppressed while the creature or object is in the sphere.

Scattering magic. Spells and magical effects like casting magic do not affect the ball. Likewise, the balls generated by different anti-imitation field magic do not cancel each other out.

Okay, we have some things to do here.

  1. Recognize magic can naturally be stopped by certain obstacles. On anti-magic field is a kind of barrier. While it is not explicitly mentioned in Discover magicis there an existing rule that the Discover magic can be stopped. We can now look at the language of antimagic field to see if it would qualify.

  2. Antimagic field Clearly suppresses any magic (except those created by an artifact or deity). Discover magic is not created by an artifact or deity, so it should be suppressed as a whole. It can not protrude and is therefore not recognized. There is nothing to discover.

  3. The rules in antimagic field over Disperse magic also implies that interactions between the field and other spells have no effect. Just like Disperse magic I can not and do not interact with the field Discover magic,

Narrative casts the character Discover magicbut they get a zero result from the field. If the character knows he has magic items and does not get an answer, he knows something is wrong. But otherwise reading out Discover magic comes without magic (at least from the antimagic field.)

dnd 5e – Would an anti-magic field block dragon breathing spell targets?

An anti-magic field prevents the Dragon Breath spell from affecting targets in an anti-magic field. The description of the spell says

You touch a willing creature and give it the power to spit magical Energy from the mouth …

(Focus on mine)

This shows that this effect should be magical and therefore does not work in an antimagic field in which

Spells and other magical effects, except those created by an artifact or deity, are suppressed (inside) and can not protrude

Database Design – What is an alternative solution for using a null value for a foreign key field?

There are some tables in my database that contain a foreign key field that is linked to another table. The problem is that the value for this field will not always be there, so sometimes I need to insert a null foreign key field. Working out:

I have a table Sense_LanguageSource Here are listed individual etymologies of entries in a dictionary. This has the following fields:

  • LanguageSourceID (PK – Autonumber)
  • SenseFK (FK number)
  • language code (FK number)
  • SourceWord (short text)
  • LanguageSourceType (short text)
  • IsWaseieigo (yes / no)

The LanguageCode Field is the problematic case. It is used to list the language from which the etymology is derived. In this case, it is a foreign key that is linked to a LanguageCodeValue Table containing both the ISO-639-2B code and the full name of the language.

However, some of the etymologies that I will insert into the database have no LanguageCodes, so I would need to include a 0 in this field. Initially Access did not allow me to do that, so I disabled referential integrity. When I reopened the database, Access said the database was compromised and needed repair. So I think I need an alternative solution.

I would less normalize it and just have a text box for the LanguageCode in it, but there are two tables that refer to that LanguageCodeValue It seems to make sense to have a table that describes what every LanguageCode refers to. The solutions that come to my mind are:

  1. Remove the relationship between the LanguageCode Fields and the LanguageCodeValue table (so it's just a reference table and not linked) and just use it SELECT asks if I need to look up the meaning of the LanguageCode.

  2. Keep the join between the tables without referential integrity to allow null foreign keys, and hope that the database will not fail.

  3. Insert a "null" value in this LanguageCodeValue table to reference so that instead of entering a null foreign key, I can only reference a record that means nothing.

  4. Another solution?

Since I have no previous experience with databases and I am not sure which design practices are best, I would like to know which solution suits my situation best.

datetime – Date difference with taxonomy field

I use D8 and have a little age calculation problem.

I have a taxonomy term "animal". It has a field "name" and "date of birth".

I have a Content Type "Test Results". It has a "date of exam" and "animal" fields. The field "animal" is a reference to the taxonomy term "animal".

I would like to have another field that calculates the age of the animal at the time of the test. So: "date of the exam" – "date of birth" = "age at the time of the exam".

I do not know how to do that. I have "computed field" installed, but do not know PHP.

Can you help me?



Allow a unique e-mail field for multiple web forms

I have two web forms with similar data but different conditions. One form is filled out by one employee and the other by a supplier. I do not want to see any duplicates in these forms. Employees and suppliers both have different web forms, but the same data. I want to make the email field unique to these two web forms. Is it possible? OR Can I merge these forms and display them differently?