While trying to use
_database.Delete(pocoObjects);
I get the error:
Value cannot be null. Parameter name: key
I should have been able to tell by the name, but I didn't realize the petapoco object I was trying to delete was a list.
Instead of:
_database.Delete(pocoObjects);
I should be using:
pocoObjects.ForEach(entity => database.Delete(entity));
Related
I'm trying to get familiar with graphql. So I have an entity called Car in BE. And I have only Cars exposed.
Now I'm trying to find all the cars from Cars, where year(launch) is certain say 2001. It's actually a variable. Now I think the following query should work.
query GetCars($y: String!) {
cars({ year: $y }) {
id
year
}
}
But it gives me error saying, Expected Name found {, it throws the error at the second dollar sign.
filters and where is also undefined.
Can anyone give me some hint to resolve this problem?
Using: GraphiQL
In cars({ year: $y}) the name of your argument is missing - arguments always need to have a name in GraphQL and the name of your arguments and their GraphQL type are defined in your schema.
Assuming your cars fields has an argument called year in your schema, you need to rewrite your query to: cars(year: $y).
Assuming your cars fields has a filter or something like that defined in the schema and that filter expects an input object type that has - maybe among others - a field year, you would write: cars(filter: { year: $y }).
I have a table where it's beneficial to generate a pre-calculated value in the database engine rather than in my application code. For this, I'm using Postgres' generated column feature. The SQL is like this:
ALTER TABLE "Items"
ADD "generatedValue" DOUBLE PRECISION GENERATED ALWAYS AS (
LEAST("someCol", "someOtherCol")
) STORED;
This works well, but I'm using Sequelize with this database. I want to find a way to define this column in my model definition, so that Sequelize will query it, not attempt to update a row's value for that column, and ideally will create the column on sync.
class Item extends Sequelize.Model {
static init(sequelize) {
return super.init({
someCol: Sequelize.DOUBLE,
someOtherColl: Sequelize.DOUBLE,
generatedValue: // <<<-- What goes here??
});
}
}
How can I do this with Sequelize?
I can specify the column as a DOUBLE, and Sequelize will read it, but the column won't be created correctly on sync. Perhaps there's some post-sync hook I can use? I was considering afterSync to drop the column and re-add it with my generated value statement, but I would first need to detect that the column wasn't already converted or I would lose my data. (I run sync [without force: true] on every app startup.)
Any thoughts, or alternative ideas would be appreciated.
Until Sequelize supports readOnly fields and the GENERATED datatype, you can get around Sequelize with a custom datatype:
const Item = sequelize.define('Item', {
someCol: { type: DataTypes.DOUBLE },
someOtherCol: { type: DataTypes.DOUBLE },
generatedValue: {
type: 'DOUBLE PRECISION GENERATED ALWAYS AS (LEAST("someCol", "someOtherCol")) STORED',
set() {
throw new Error('generatedValue is read-only')
},
},
})
This will generate the column correctly in postgres when using sync(), and prevent setting the generatedValue in javascript by throwing an Error.
Assuming that sequelize never tries to update the field if it hasn't changed, as specified in https://sequelize.org/master/manual/model-instances.html#change-awareness-of-save, then it should work.
Iam new to graphql.Iam implementing a react-native app using aws appsync.Following is the code i have written in schema
type Messages {
id: ID!
createdAt: String!
updateAt: String!
text: String!
sendBy: Person!
#relation(name: "UserMessages")}
type Person {
id: ID!
createdAt: String!
updateAt: String!
name: String!
messages: [Messages!]!
#relation(name: "UserMessages")}
When i tried to query the sendBy value it is giving me an error saying
query getMessages{
getMessages(id : "a0546b5d-1faf-444c-b243-fab5e1f47d2d") {
id
text
sendBy {
name
}
}
}
{
"data": {
"getMessages": null
},
"errors": [
{
"path": [
"getMessages",
"sendBy"
],
"locations": null,
"message": "Cannot return null for non-nullable type: 'Person' within parent 'Messages' (/getMessages/sendBy)"
}
]
}
Am not understanding that error please help me.Thanks!! in Advance
This might sound silly, but still, developers do this kind of mistakes so did I. In subscription, the client can retrieve only those fields which are outputted in the mutation query. For example, if your mutation query looks like this:
mutation newMessage {
addMessage(input:{
field_1: "",
field_2: "",
field_n: "",
}){
field_1,
field_2
}
}
In the above mutation since we are outputting only field_1 & field_2. A client can retrieve the only subset of these fields.
So if in the schema, for a subscription if you have defined field_3 as required(!), and since you are not outputting field_3 in the above mutation, this will throw the error saying Cannot return null for non-nullable type: field_3.
Looks like the path [getMessages, sendBy] is resolving to a null value, and your schema definition (sendBy: Person!) says sendBy field cannot resolve to null. Please check if a resolver is attached to the field sendBy in type Messages.
If there is a resolver attached, please enable CloudWatch logs for this API (This can be done on the Settings page in Console, select ALL option). You should be able to check what the resolved Request/Response mapping was for the path [getMessages, 0, sendBy].
I encountered a similar issue while working on my setup with CloudFormation. In my particular situation I didn't configure the Projection correctly for the Global Secondary Indexes. Since the attributes weren't projected into the index, I was getting an ID in the response but null for all other values. Updating the ProjectionType to 'ALL' resolved my issue. Not to say that is the "correct" setting but for my particular implementation it was needed.
More on Global Secondary Index Projection for CloudFormation can be found here: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-dynamodb-projectionobject.html
Attributes that are copied (projected) from the source table into the index. These attributes are additions to the primary key attributes and index key attributes, which are automatically projected.
I had a similar issue.
What happened to me was a problem with an update resolver. I was updating a field that was used as GSI (Global Secondary Index). But I was not updating the GSI, so when query by GSI the index exists but the key for that attribute had changed.
If you are using Dynamo DB, you can start debugging there. You can check the item and see if you have any reference to the primary key or the indexes.
I had a similar issue.
for me the problem was lying with the return type of the schema . As i was doing a query with PK on dynamodb table ..it was returning a list of items or data you can say . but in my schema i had a schema define as a singular struct format .
Error was resolved when i just made the return type in schema as list of items .
like
type mySchema {
[ID]
}
instead of
type mySchema
{
id : ID!
name : String!
details : String!
}
This error is thrown for multiple reasons . so your reason could be else but still i just posted one of the scenarios.
I have database field called name. And i have used user.name in my application. Now I have something like salutation which i wanted to append with the name. So what i basically want is when i am accessing name via user.name it should fetch the value from instance method rather then database field.
def name_with_salutation
"#{salutation} #{name}"
end
So when i am accessing name via user.name it should respond with user.name_with_salutation. I have tried alias_method but it shows stack level too deep because name is getting used in name_with_salutation so it got stuck in infinite process.
I am trying this because i do not want to replace name with name_with_salutation throughout the application. This should not apply when i am assigning values user.name = "abc".
Please let me know, How this will be done.
To overwrite an original Model method, you can write a method with same name, and then use read_attribute(:attr) to represent the original attribute value.
Given name attribute exist, to overwrite #name:
def name
"#{salutation} #{read_attribute(:name)}"
end
I have 15 roles for my ListModel. I am not specifying all of them for every ListElement because they are not always required.
I have common code for displaying values based on roles.
So if my current ListElement doesnt have role a defined, and I'm trying to check for that value, it throws a reference error.
I tried to catch this error using (a==undefined || a== null) but it still throws a reference error on a.
Is there any other option to catch this error? (except for writing all roles for all ListElements)
For convenience model roles available as delegate's properties (as you do currently). You can access them with the qualified model name instead. E.g. model.a instead of just a. If a role is not available value of expression will be undefined, but it's not an error. Typical work around is to use boolean operators, e.g. model.a || "default value".
Try with this:
if (a) {
// Your stuff here
}