BreezeJS malformed OData query Url when using “startsWith”

问题

Hello I am trying to execute a query using breezejs 1.3.4 . My query is the following

function getContacts() {

            var query = breeze.EntityQuery
                .from("Contacts").where("Desc", "startsWith", "P");


            return manager.executeQuery(query)
              .then(getSucceeded).fail(getFailed); 

        }

"Desc" is a string property in my "Contacts" C# backend model. Tha problem is that the Query URL is formatted like this .../api/Application/Contacts?$filter=startswith(Desc%2Ctime'P')%20eq%20true

The word time is added before "P" and I get a this exception in the Response

{"$id":"1","$type":"System.Web.Http.HttpError, System.Web.Http","Message":"The query specified in the URI is not valid.","ExceptionMessage":"Unrecognized 'Edm.Time' literal 'time'P''

If in the comparison I use a lower case "p" then the Url is costructed as it should be like this "$filter=startswith(Desc%2C'p')%20eq%20true` .

I don't have the same problem when using other UpperCase letters of the english alphabet.

Does anyone have an idea what am I missing, I can't figure out why the word "time" is added in that specific query?

Thank you.

回答1:

We were able to reproduce the problem.

While the exception message is confusing, I believe you might be getting the error because you have not associated that the resource name 'Contacts' with an EntityType of presumably 'Contact'.

What is happening is that when Breeze tries to build the query it will usually use its metadata to correctly format the url query string to send to the server. The critical part of this process involves determining the EntityType associated with the resourceName given in the 'from' clause of the query ('Contacts' in your case). Breeze uses a resource name to entity type map to do this, but if it cannot find a mapping, it will still continue to build the url because we still need to support ad-hoc requests against endpoints for which we have no metadata.

You can update this map yourself via the MetadataStore.setEntityTypeForResourceName method. If you are using the Entity Framework, this map is initially populated based on the EntityType name/Entity Set name mapping that is part of your EDMX model. So in your case you can either modify your EDMX model or call the setEntityTypeForResourceName method directly.

Unfortunately, without the metadata Breeze has to infer the datatypes in the query. So in your case

"Desc", "startsWith", "P"

since Breeze can't determine that "Desc" is a 'string' property of your Contract EntityType it tries to infer the 'dataType' of "Desc" based on the value 'P'. Unfortunately, 'P' is a valid ISO8601 'duration' value ( a way to express a 'Time' datatype), so Breeze incorrectly tries to construct a query string with 'P' treated as a 'Time' constant. This is why your code works with a lower case 'p' ( not a valid duration value).

This inference logic can certainly be improved and we have a fix that will allow us to do exactly that coming out in the next release. However... the better and more general solution to this type of issue is to get the 'resourceName/entityType' mappings correct in the first place.

Hope this helps.

来源：https://stackoverflow.com/questions/16829907/breezejs-malformed-odata-query-url-when-using-startswith

标签

odata

breeze