Currently, I have been adding mapping through REST Api and programatically indexing documents using NEST.
However, I recently came across NEST's DefaultMappingFor (in ConnectionSettings) and wondering how it's used. (Won't be able to spike soon hence asking.)
Question: In the source code, if I set mapping using the DefaultMappingFor, does that mean it is not necessary to create the mapping using the Rest Api because, maybe(I think), and NEST will use the declared default mapping whenever a document is indexed?
Thank you.
DefaultMappingFor() and DefaultMappingFor<T>() allows you to configure defaults for a given CLR type. Both allow you to configure:
The default index name to use, through the .IndexName() method
The default type name to use, through the .TypeName() method
The default relation name to use when mapping as Parent/Child relationship, through the .RelationName() method
In addition, DefaultMappingFor<T>() allows you to configure:
The property on the type to use for the id of the document through the .IdProperty() method
The property on the type to use for the routing parameter (useful to set for Parent/Child relationships, but also when you need routing), through the .Routing() method
Which properties to ignore when serializing the type through the .Ignore() method
Which properties should be serialized with different field names through the .PropertyName() method
Setting any of these for a type means that NEST will use these over any conventions it has. The typical ones to use are .IndexName() and .TypeName() (although types are removed in Elasticsearch 6.x), and means that you don't need to specify either of these on each request (unless you want to override this default mapping too).
Related
I use spring-data-cassandra, and have entity like this:
#Table("users")
public class User {
#Column("permissions")
#CassandraType(type = DataType.Name.SET, typeArguments = {DataType.Name.TEXT})
public Set<String> permissions = new HashSet<>();
}
In cassandra I have table users with field permissions of type Set. It works fine when I store some values in the set, but when I try to store empty set, it becomes null when I read such entity from the repository.
Is there a way to force spring-data-cassandra to change null to empty HashSet? Or can I somehow add custom reader for this specific property of the entity?
TL;DR;
That's Cassandra's default behavior to return null for empty Collection and Map-typed columns.
Further Read
Cassandra returns null values for lists, sets, and maps, which do not contain any items. This is especially unfortunate when using classes with pre-initialized fields as seen in your question. There's an open ticket (DATACASS-266 - Loading empty collection-typed properties overwrites pre-initialized fields) in the issue tracker - as of now, without comments or votes.
We're not exactly sure whether it's a good idea to skip setting properties or apply some sort of defaulting when dealing with empty (null) collections as this raises follow-up questions what to do when:
Creating an instance through constructor creation: A value is required in such case. For property access, we could omit to set the property, for constructor creation we must provide a value.
The pre-initialized collection contains items but the one received from Cassandra is null.
We assume, the change would be applied, what will happen with already existing code that assumes empty collections default to null.
A possibility to address this behavior could be configuration on MappingCassandraConverter or an extension point to override so users can apply their own empty collection behavior.
I've been trying to eliminate the null collections in my model objects as well, and while it may not be possible to do that at the Spring Data level currently (version 2.1.x), there are some options you can consider:
Use property access for the field in question (i.e. use the annotation #AccessType(PROPERTY)), and in the setter method, set the field to an empty collection when the argument is null.
Define a compatible (see below) constructor that sets the field to an empty collection when a null is provided (and if the model is mutable, you may still want to provide the setter as above).
There are some caveats to ensure Spring Data Cassandra uses the desired constructor (e.g. don't provide a no argument constructor), so it's critical to review the "Object Mapping Fundamentals" section of the reference guide (https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#mapping.fundamentals).
Among the recommendations in that reference guide (as of version 2.1 at least) is to use an all argument constructor and make model objects immutable, which would work well with the constructor-based approach to handling nulls. Though it does mean writing and maintaining the constructor to handle the nulls rather than relying on Lombok's #AllArgsConstructor.
I have used the property access approach in one case, but not the constructor approach. However I do intend go the constructor route when adding new or model classes (I'm a fan of immutable objects, and will explore that route even without any collection fields)
I believe Spring Data Cassandra 2.0 also added persistence lifecycle callbacks which is another possible option I suppose, but I ruled that out, mainly because the logic would not reside in the model class itself (as well as going against the recommendations from the creators of the framework)
I'm guessing that the type is used for CRUD operations. Is it used for anything else besides that? I'm wondering what impact there could be from configuring how it gets populated.
The _class field is written to allow polymorphic properties in your domain model. See this sample:
class Wrapper {
Object inner;
}
Wrapper wrapper = new Wrapper();
wrapper.inner = new Foo();
couchbaseOperations.save(wrapper);
You see how the field inner will get Foo serialized and persisted. On the reading side of things we now have to find out which type to create an object of and the type information in Wrapper is not enough to do so as it only states Object.
That's why Spring Data object mapping persists an additional field (name customizable but defaulting to _class) to store that information to be able to inspect the source document, derive a type from the value written for that field and eventually map that document back to that particular type.
The Spring Data Couchbase reference documentation doesn't really document it, you can find information about the way this works in the docs for the MongoDB module. I've also created a ticket for Spring Data Couchbase to improve on the docs for that.
I'm trying out Spring Data with MongoDB and REST as shown here. One thing I noticed is that to sort results, you add a query parameter named .dir with a value of "asc" or "desc".
In many REST APIs I've used, the mechanism for sorting was to simply put a minus ("-") symbol in front of the property name in the sort (or order) parameter.
Is there any way I could customize Spring to allow for this behavior?
I remembered I stumbled on this thread before I made the customized resolver. You can use SimpleSortHandlerMethodArgumentResolver class on https://github.com/sancho21/spring-data-commons/commit/6c90a9cfcb50b2ed0e7a25db0cfd64d36e7065da
Please comment to support its adoption on https://github.com/spring-projects/spring-data-commons/pull/166/files
As for reminder, in order to use this class, you need to inject an instance of it into the existing the constructor of existing PageableHandlerMethodArgumentResolver instance.
There are lots of examples of using ODataConventionModelBuilder with simple, contrived models, often just a single class.
But there's nothing that actually explains what the conventions are; how to code a model that complies with convention. There's no official documentation for it.
So what's the convention?
From what I've seen so far, the conventions are those used by Entity Framework, as opposed to any new ones for OData. Please correct me if I am wrong.
More on Code-first conventions, below, but there are many more in the Julie Lerman book I have yet I cannot find an exhaustive list of them on the web.
http://blogs.msdn.com/b/efdesign/archive/2010/06/01/conventions-for-code-first.aspx
Update
The EF modelling conventions system is pluggable and each convention is represented by a class encapsulating the behaviour, and those classes are listed here:
http://msdn.microsoft.com/en-us/library/system.data.entity.modelconfiguration.conventions(v=vs.113).aspx
However that doesn't help with which ones are applicable or used by the ODataConventionModelBuilder if any.
AssociationInverseDiscoveryConvention - Provides convention to detect navigation properties to be inverses of each other when only one pair of navigation properties exists between the related types.
AttributeToColumnAnnotationConvention - A general purpose class for Code First conventions that read attributes from .NET properties and generate column annotations based on those attributes.
AttributeToTableAnnotationConvention - A general purpose class for Code First conventions that read attributes from .NET types and generate table annotations based on those attributes.
ColumnAttributeConvention - Represents a convention to process instances of ColumnAttribute found on properties in the model.
ColumnOrderingConvention - Represents a convention to apply column ordering specified via ColumnAttribute or theDbModelBuilder API.
ColumnOrderingConventionStrict - Convention to apply column ordering specified via ColumnAttribute or theDbModelBuilder API. This convention throws if a duplicate configured column order is detected.
ComplexTypeAttributeConvention - Represents the convention to process instances of ComplexTypeAttribute found on types in the model.
ComplexTypeDiscoveryConvention - Represents a convention to configure a type as a complex type if it has no primary key, no mapped base type and no navigation properties.
ConcurrencyCheckAttributeConvention - Represents the convention to process instances of ConcurrencyCheckAttributefound on properties in the model.
Convention - A convention that doesn't override configuration.
DatabaseGeneratedAttributeConvention - Represents a convention to process instances of DatabaseGeneratedAttribute found on properties in the model.
DecimalPropertyConvention - Convention to set precision to 18 and scale to 2 for decimal properties.
DeclaredPropertyOrderingConvention - Represents a convention to move primary key properties to appear first.
ForeignKeyAssociationMultiplicityConvention - Represents a convention to distinguish between optional and required relationships based on CLR nullability of the foreign key property.
ForeignKeyDiscoveryConvention - Represents a base class for conventions that discover foreign key properties.
ForeignKeyIndexConvention - Represents a convention to introduce indexes for foreign keys.
ForeignKeyNavigationPropertyAttributeConvention - Represents a convention to process instances of ForeignKeyAttribute found on navigation properties in the model.
ForeignKeyPrimitivePropertyAttributeConvention - Represents a convention to process instances of ForeignKeyAttribute found on foreign key properties in the model.
IdKeyDiscoveryConvention - Convention to detect primary key properties. Recognized naming patterns in order of precedence are: 1. 'Id' 2. [type name]Id Primary key detection is case insensitive.
IndexAttributeConvention - A convention for discovering IndexAttributeattributes on properties and generatingIndexAnnotation column annotations in the model.
InversePropertyAttributeConvention - Represents a convention to process instances of InversePropertyAttribute found on properties in the model.
KeyAttributeConvention - Convention to process instances ofKeyAttribute found on properties in the model.
KeyDiscoveryConvention - Represents a base class for conventions that discover primary key properties.
ManyToManyCascadeDeleteConvention - Convention to add a cascade delete to the join table from both tables involved in a many to many relationship.
MappingInheritedPropertiesSupportConvention - Convention to ensure an invalid/unsupported mapping is not created when mapping inherited properties
MaxLengthAttributeConvention - Represents a convention to process instances of MaxLengthAttribute found on properties in the model.
NavigationPropertyNameForeignKeyDiscoveryConvention - Convention to discover foreign key properties whose names are a combination of the dependent navigation property name and the principal type primary key property name(s).
NotMappedPropertyAttributeConvention - Represents a convention to process instances of NotMappedAttribute found on properties in the model.
NotMappedTypeAttributeConvention - Represents a convention to process instances of NotMappedAttribute found on types in the model.
OneToManyCascadeDeleteConvention - Provides a convention to enable cascade delete for any required relationships.
OneToOneConstraintIntroductionConvention - Provides a convention to configure the primary key(s) of the dependent entity type as foreign key(s) in a one:one relationship.
PluralizingEntitySetNameConvention - Represents a convention to set the entity set name to be a pluralized version of the entity type name.
PluralizingTableNameConvention - Represents a convention to set the table name to be a pluralized version of the entity type name.
PrimaryKeyNameForeignKeyDiscoveryConvention - Convention to discover foreign key properties whose names match the principal type primary key property name(s).
PrimitivePropertyAttributeConfigurationConvention - Base class for conventions that process CLR attributes found on primitive properties in the model.
PropertyAttributeConfigurationConvention - Base class for conventions that process CLR attributes found on properties of types in the model.
PropertyMaxLengthConvention - Represents a convention to set a maximum length for properties whose type supports length facets. The default value is 128.
RequiredNavigationPropertyAttributeConvention - Convention to process instances ofRequiredAttribute found on navigation properties in the model.
RequiredPrimitivePropertyAttributeConvention - Represents a convention to process instances of RequiredAttribute found on primitive properties in the model.
SqlCePropertyMaxLengthConvention - Represents a convention to set a default maximum length of 4000 for properties whose type supports length facets when SqlCe is the provider.
StoreGeneratedIdentityKeyConvention - Represents a convention to configure integer primary keys to be identity.
StringLengthAttributeConvention - Represents a convention to process instances of StringLengthAttribute found on properties in the model.
TableAttributeConvention - Represents a convention to process instances of TableAttribute found on types in the model.
TimestampAttributeConvention - Represents a convention to process instances of TimestampAttribute found on properties in the model.
TypeAttributeConfigurationConvention - Base class for conventions that process CLR attributes found in the model.
TypeNameForeignKeyDiscoveryConvention - Convention to discover foreign key properties whose names are a combination of the principal type name and the principal type primary key property name(s).
The best explanation I'm aware of, is here
Routing Conventions in ASP.NET Web API 2 Odata
NB this is Odata 3, not odata 4
The conventions used in ODataConventionModelBuilder are described here.
As for how to code a model that complies with the conventions, that is pretty straight forward, or rather you don't need to code a model to the conventions at all. The conventions exist to simplify and standardize how an EF model is expressed in an OData Edm Model. If you find yourself manually enabling features, then you might find there is a convention that can automate this process for you. Understanding what the conventions are might help.
Your answer #LukePuplett describes some of the EF Code First conventions, they don't really apply here, not all directly anyway. I don't want to say you were wrong... ;)
The following is derived from the source code for ConventionModelBuilder.
Type and Property Conventions
NOTE: ordering is important here.
AbstractTypeDiscoveryConvention
configures all structural types backed by an abstract CLR type as abstract.
DataContractAttributeEdmTypeConvention
Configures classes that have the DataContractAttribute to follow DataContract serialization/deserialization rules.
NotMappedAttributeConvention
Ignores properties with the NotMappedAttribute from IEdmStructuredType
NotMappedAttributeConvention MUST run before EntityKeyConvention, or it will allow Keys to be excluded from the model
DataMemberAttributeEdmPropertyConvention
Configures properties that have DataMemberAttribute as optional or required on their edm type.
NOTE: This does not explicitly remove properties that have IgnoreDataMemberAttribute, but it will not explicitly add them either
DerivedTypeConstraintAttributeConvention
Adds Derived Type Constraints to the Model if required
RequiredAttributeEdmPropertyConvention
Marks properties that have RequiredAttribute as non-optional on their edm type.
DefaultValueAttributeEdmPropertyConvention
Sets default value for properties that have DefaultValueAttribute
ConcurrencyCheckAttributeEdmPropertyConvention
Marks properties that have ConcurrencyCheckAttribute as non-optional on their EDM type.
TimestampAttributeEdmPropertyConvention
Annotates a single column in a Type as the Timestamp column, even if multiple columns are annotated with the TimestampAttribute.
This is due to a SQL limitation table (the underlying concept this attribute is bounded to) that only supports one row version column per table.
ColumnAttributeEdmPropertyConvention
Marks properties that have ColumnAttribute as the target EDM type.
KeyAttributeEdmPropertyConvention
Configures properties that have the KeyAttribute as keys in the IEdmEntityType
KeyAttributeEdmPropertyConvention MUST run before EntityKeyConvention
EntityKeyConvention
This convention configures properties that are named 'ID' (case-insensitive) or {EntityName}+ID (case-insensitive) as the key.
ComplexTypeAttributeConvention
Removes primitive properties that are exposed through ComplexType definitions from the IEdmEntityType
This MUST run after Key conventions, basically overrules them if there is a ComplexTypeAttribute
IgnoreDataMemberAttributeEdmPropertyConvention
Removes properties that have IgnoreDataMemberAttribute from their edm type.
If class is a DataContract and DataMemberAttribute is present on this property, then the property will not be removed, DataMemberAttribute takes precedence
NotFilterableAttributeEdmPropertyConvention
Configures a column with fluent IsNotFilterable() if it has a NotFilterableAttribute annotation. This will specify that the property cannot be used in the $filter OData query option.
This is the same implementation as NonFilterableAttribute and its related NonFilterableAttributeEdmPropertyConvention
NonFilterableAttributeEdmPropertyConvention
Configures a column with fluent IsNotFilterable() if it has a NonFilterableAttribute annotation. This will specify that the property cannot be used in the $filter OData query option.
This is the same implementation as NotFilterableAttribute and its related NotFilterableAttributeEdmPropertyConvention;
NotSortableAttributeEdmPropertyConvention
Configures a column with fluent IsNotSortable() if it has a NotSortableAttribute annotation. This will specify that the property cannot be used in the $orderby OData query option.
UnsortableAttributeEdmPropertyConvention
Configures a column with fluent IsNotSortable() if it has a UnsortableAttribute annotation. This will specify that the property cannot be used in the $orderby OData query option.
NotNavigableAttributeEdmPropertyConvention
Configures a column with fluent IsNotNavigable() if it has the NotNavigableAttribute annotation. This will specify that the property cannot be navigated in OData query.
This does not preclude $expand, it means that the propert cannot be used to traverse to the associated resource using an Entity Path, for instance if ProductType had this attribute, and was a navigation property that returned a ProductType reference, the following OData path would not be servived: ~/api/products(112)/ProductType this is a feature from the updates to support Containment.
NotExpandableAttributeEdmPropertyConvention
Configures a column with fluent IsNotExpandable() if it has a NotExpandableAttribute annotation. This will specify that the property cannot be used in the $expand OData query option.
NotCountableAttributeEdmPropertyConvention
Configures a column with fluent IsNotCountable() if it has a NotCountableAttribute annotation. This will specify that the $count cannot be applied on the property.
MediaTypeAttributeConvention
Configures a class with fluent MediaType() which marks this entity type as media type.
AutoExpandAttributeEdmPropertyConvention
Configured the AutoExpand feature of a column when it has the AutoExpandAttribute annotation.
AutoExpandAttributeEdmTypeConvention
When AutoExpandAttribute is placed on a class it can specify all navigation properties are auto expanded.
MaxLengthAttributeEdmPropertyConvention
Configures string or binary properties that have the MaxLengthAttribute annotation.
PageAttributeEdmPropertyConvention
Sets the page size and Max Top of the entity type based on the PageAttribute annotation if present on any of the properties in the class.
There is no added value of supporting this on a property level, but it is offered as a redundancy for poorly configured code.
PageAttributeEdmTypeConvention
Sets the page size and Max Top of the entity type based on the PageAttribute annotation on the class.
ExpandAttributeEdmPropertyConvention
Configures OData $expand query option for navigation columns with ExpandAttribute annotation.
ExpandAttributeEdmTypeConvention
Set the ExpandConfigurations of navigation properties of this structural type based on the ExpandAttribute annotation on the class.
CountAttributeEdmPropertyConvention
Configures the $count OData query options for specific columns with the CountAttribute annotation. The $count OData query option can be explicity enabled or disabled with the CountAttribute annotation.
CountAttributeEdmTypeConvention
Set whether the $count can be applied on the edm type. The $count OData query option can be explicity enabled or disabled with the CountAttribute annotation.
OrderByAttributeEdmTypeConvention
Configures the OData $orderby query option settings for a type based on the OrderByAttribute on the class or on the properties.
When used on a class, the default $orderby value can be specified.
When used on properties it can also prevent that property from being referenced in an $orderby OData query option.
FilterAttributeEdmTypeConvention
Configures the OData $filter query option settings for a type based on the FilterAttribute on the class or properties.
OrderByAttributeEdmPropertyConvention
Configures the OData $orderby query option settings for a type based on the OrderByAttribute on the class or on the properties.
When used on a class, the default $orderby value can be specified.
When used on properties it can also prevent that property from being referenced in an $orderby OData query option.
FilterAttributeEdmPropertyConvention
Configures the OData $filter query option settings for a type based on the FilterAttribute on the class or on the properties.
When used on a class, the default $filter value can be specified.
When used on properties it can also prevent that property from being referenced in an $filter OData query option.
SelectAttributeEdmTypeConvention
For classes that have SelectAttribute, the attribute will list the properties that can be referenced by the $select OData query option for this structural type.
SelectAttributeEdmPropertyConvention
Configures the OData $select query option settings for a type based on the SelectAttribute on the class or on the properties.
When used on a class, the default $select value can be specified.
When used on properties it can also prevent that property from being referenced in an $select OData query option.
INavigationSourceConvention's
SelfLinksGenerationConvention
Generates Item and Edit links in the OData annotations.
NavigationLinksGenerationConvention
Generate links without cast for declared and inherited navigation properties, or with a cast in derived types.
AssociationSetDiscoveryConvention
This convention adds an association set for each EDM navigation property defined in this type, its base types and all its derived types.
The target navigation source chosen is the default navigation source for the navigation property's target entity type.
The default navigation source for an entity type is the navigation source that contains entity of that entity type.
If more than one navigation source match, the default navigation source is none.
If no navigation sources match the default navigation source is the default navigation source of the base type.
IEdmFunctionImportConventions's
ActionLinkGenerationConvention
calls action.HasActionLink(..) if the action binds to a single entity and has not previously been configured.
FunctionLinkGenerationConvention
calls function.HasFunctionLink(..) if the function binds to a single entity and has not previously been configured.
Interesting notes:
I tried to do some research on the history of NotFilterableAttribute vs NonFilterableAttribute but struggled to find a point of divergence in the open source libraries. Both of these attributes exist in the VS 2013 help docs and the System.Web.OData.Query namespace. I assume at one point two different namespaces or libraries were merged together and the attributes were retained for backward compatibility.
What should have happened in the associated commit was that one of these attributes should have been deprecated (annotated with [Obsolete]) and in a future version that deprecated class should have been removed, certainly long before now.
This same situation exists with NotSortableAttribute and UnsortableAttribute...
Some of these conventions have the same implementation in two different convention classes, one mapped to the Entity Type, the other to the Property. At first glance this looks redundant, but it is necessary for attributes that support both class and property annotation. The reason it is necessary is that the presence of the associated attribute triggers the convention to be evaluated at all. The OData conventions do not operate like the EF code first conventions that evaluate all types and properties for a match. The model is iterated, not the conventions. A class level attribute application, like PageAttribute if we want to allow it to be specified on the property it still needs to apply the logic to the Edm Type. The reverse is try to for FilterAttribute that can be declared once on the Edm Type with an array of properties, or you can manage the properties individually, you might even have both, with property level attributes to explicitly prevent $filter access.
I can only speculate that someone decided that this was a necessary performance measure as these conventions are evaluated at runtime, we could measure it later if anyone is interested ;)
For these classes that have multiple similar implementations, I would have designed the logic such that there was a single class that defined the common logic and the concrete types would reference it. This satisfies the DRY principal but also makes the code and patterns like this more discoverable.
Hi I'm trying to get Breeze to create a metadata store but its failing with the message
NamingConvention for this server property name does not roundtrip properly
I had the same self referencing loop with the out of the box Web API and was able to solve but setting
json.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
Any help or solutions would be greatly appreciated.
Thanks
Ok so I solved my own question. My table names all started with lower case, so when I got the round trip error it was because it would look at an entity such as refLookup which was being seen as RefLookup by Breeze but was also referenced an entity as refLookup (no camel case as thats the name of the entity). So I just named all my tables in the database with upper case characters. Hope that helps some one in the future.
The Breeze NamingConvention facility supports property aliasing, not entity type name aliasing. Therefore the spelling of the entity type name must match the server-side type name exactly ... even if you choose the camelCasing NamingConvention or create your own custom NamingConvention plug in.
That's why I'm surprised that you had any difficulty with the table/entity class name casing.
I am unable to reproduce this error. Here is what I tried
Added a 'foo' table to my database
Created a corresponding foo class
Exposed it from the Web API controller as a foos query action method
Queried on the Breeze client for all foos
Breeze client had no trouble returning my (two) foo entities.
Note that I did not try to mess with the NamingConvention on the client. I kept the default ... which is that every client entity property name is the same as its corresponding server property name. As I said, the NamingConvention doesn't do anything with the entity type name and there is no representation in the metadata for a difference between server and client entity type names.
Do you think otherwise? Can you provide a sample?
A strong word of caution: Do NOT change the Json.NET property naming convention. All name aliasing must be done by Breeze on the client.
In general, one should not change a Json.NET configuration setting if the [BreezeController] attribute set that value. The only exception I can think of is null value handling; Breeze tells Json.NET to ignore nulls. I think that is a mistake ... and you can tell Json.NET to send null values if you wish.
I had the same issue when using two managers. I found that if you are using the global
breeze.NamingConvention.{whateverYouUse}.setAsDefault();
it needs to be set prior to creating the manager. Also if you are forcing the json serialization to a specific naming convention on the server the naming convention on the client should match. I am using the breezecontext and as long as its set prior to the manager all works as planned..maybe you don't need the server side setting?